1
ECONOMIC STUDY OF FARMLAND EROSION
CONTROL PRACTICES IN ENUGU STATE,
NIGERIA
BY
EZE SILAS OZOEMENA
PG/M.SC/06/41581
DEPARTMENT OF AGRICULTURAL ECONOMICS
FACULTY OF AGRICULTURE
UNIVERSITY OF NIGERIA, NSUKKA
SEPTEMBER, 2012
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TITLE PAGE
ECONOMIC STUDY OF FARMLAND EROSION CONTROL
PRACTICES IN ENUGU STATE, NIGERIA
A THESIS
SUBMITTED TO THE DEPARTMENT OF AGRICULTURAL
ECONOMICS UNIVERSITY OF NIGERIA, NSUKKA IN
PARTIAL FULFILLMENT OF THE REQUIREMENTS
FOR THE AWARD OF MASTER OF SCIENCE IN
AGRICULTURAL ECONOMICS
BY
EZE SILAS OZOEMENA
PG/M.SC/06/41581
SEPTEMBER, 2012
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DEDICATION
This research work is dedicated
to
God Almighty
and
My beloved wife and Daughter Mrs. Eze Lucy,
Chinelo and Little Miss Eze Favour Akachukwu.
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CERTIFICATION
Eze Silas Ozoemena a postgraduate student of Department of Agricultural
Economics with registration number PG/M.Sc/06/41581 has satisfactorily completed the
requirement for the course and research work for the award of Master of Science (M.Sc)
in Agricultural Economics. This research work has been approved for the Department of
Agricultural Economics, University of Nigeria, Nsukka.
----------------------------DR. A.A. ENETE
SUPERVISOR
---------------DATE
--------------------------------------PROF. E.C. OKORJI
DATE
HEAD OF DEPARTMENT
------------------------------------PROF. J.A. MBANASOR
EXTERNAL EXAMINER
----------------DATE
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ACKNOWLEDGEMENT
With heart full of joy, I first of all appreciate God Almighty who in his infinite
mercy and love has provided me with abundant spiritual and material protection and
guidance throughout the period of this porgramme.
I am very much indebted to my industrious and articulate supervisor Dr. A.A.
Enete for his constructive criticism, thorough supervision and advice that has brought my
dissertation to a logical conclusion. May God shower him and his family with abundant
blessings.
However, I must not forget in a hurry the programme Manager ENADEP Mr.
Onyemaechi Nwodo and the man incharge of monitoring and evaluation unit, Enugu
State FADAMA programme Mr. Michael Nwobodo who provided me with the materials
and assistance of the Agricultural extension agents of three agricultural zones of Enugu
State in the persons of Mr. Walter Oti (Enugu North), Uche Okonkwo (Enugu East) and
Charles Nnaji (Enugu West). It is well with them.
My sincere appreciation also goes to; Prof. Akamigbo, F.OR., Ofomata G.E.K.
Prof. Okoye, C.U., Dr. Ozor, N., Mr. Onyekuru Anthony, Eze Emmanuel IK, Ade, and
host of others for providing me with some useful materials that guided my research work.
Finally, I am not forgetting to thank my typists, friends and well wishers
particularly my family members headed by Mr. Alfred Eze for empowering me with
human and material resources throughout my academic pursuit. May God reward them
million folds and shower them with his favour.
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TABLE OF CONTENTS
CHAPTER ONE
1.0 INTRODUCTION
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1.1 Background of the Study -
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1.2 Statement of the Problem -
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1.3 Objectives of the Study
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1.4 Research Hypotheses
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1.5 Significance of the study -
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CHAPTER TWO
2.0 Literature Review -
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2.1 Concept of soil erosion
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2.2 History of soil erosion
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2.3 Mechanism of soil erosion
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2.4 Economics of soil erosion -
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2.5 Factors responsible for erosion in Enugu state
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2.6 Classification of erosion -
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2.7 Erosion control
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2.8 Problems and effects of erosion -
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2.9 Documentation of erosion site in Enugu State
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2.10 Review of existing erosion control practices
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2.11 Theoretical framework -
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2.12 Analytical framework
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2.12.1 Multinomial logit model
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2.12.2 Partial budgeting
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2.12.3 Duncan‘s multiple-range test -
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CHAPTER THREE
3.0 Methodology
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3.1 The Study Area
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3.2 Sampling Procedure
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3.3 Data Collection
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3.4 Data Analysis
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3.5 Test of Hypothesis
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3. 6 Model Specification
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3.6.1 Multinomial Logit Model
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3.6.2 Partial Budget Analysis -
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3.6.3 Duncan‘s Multiple Range Test -
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3.6.4 Likert rating scale technique
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3.6.5 Profitability index
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4.1.2 Combination of erosion control practices applied by farmers - -
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CHAPTER FOUR
4.0 Results and Discussion
4.1 The erosion control practices applied by farmers in the area
4.1.3 Description of Farmland Erosion Control practices applied by Farmers-
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4.2 Costs and returns for the erosion control practice
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4.2.1 Multiple Cropping Partial Budget
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4.2.2. Construction of Bonds -
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4.2.3. Ridging Across the Slope
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4.2.4 Cover Cropping -
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4.2.5 Duncan‘s Multiple Range Test -
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4.3 Socioeconomic Factors Affecting Farmer‘s use of Particular Erosion Control 80
4.4 Possible Causes of Erosion on the Farmland from the Farmers Perspective
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4.4.2 Causes and extent of cause of erosion as perceived by the farmers
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CHAPTER FIVE
5.0 Summary, Conclusion and Recommendations
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5.1 Summary -
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5.2 Conclusion
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5.3 Recommendations -
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REFERENCES
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APPENDIX -
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LIST OF TABLES
Table 4.1.1 Frequency, Percentage and Rank Distribution of
Farmland Erosion Control Practices.
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Table 4.1.2 Frequency and Percentage Distribution of Combination of
Erosion Control Practices.
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Table 4.2.1 Multiple Cropping Partial Budget
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Table 4.2.2 Construction of Bonds Net Benefits
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Table 4.2.3: Ridging Across the Slope Partial Budget
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Table 4.2.4 Cover Cropping Partial Budget -
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Table 4.2.5.1 Duncan‘s Multiple Range Test for Net-Benefit
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Table 4.3.0 Result of Multinomial Logit Regression Analysis of the
Socioeconomic Characteristics Affecting the Farmers Use of Multiple
Cropping, Construction of Bonds, Ridging Across the Slope, and Cover
Cropping in Enugu State 83
Table 4.4.1 Frequency and Percentage Distribution of the Possible Causes of
Erosion on the Farmland.
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Table 4.4.2.1: Mean and Standard deviation Distribution of the Perception of
Extent of Causes of Farmland Erosion by the Farmers.
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FIGURES
Fig. 1: Technology Options for Erosion Management on Newly Cleared Land
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Fig. 2: Soil Erosion Map of South Eastern Nigeria -
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Fig. 3: Potential Erosion Map of South Eastern Nigeria
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Fig.4: Soil Type Map of Enugu State -
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ABSTRACT
An economic analysis of farmland erosion control practices was conducted in Enugu
State, southeastern Nigeria. The study aimed at identifying and describing the erosion
control practices applied by the farmers, determining the net-benefit of erosion control
practices, determining the socio-economic factors affecting the farmers‘ use of a
particular erosion control practice and identifying from the farmers perspective the
possible causes and extent of cause of erosion on the farmland as well as making
recommendations based on the findings. An interview schedule and structured
questionnaire were used to elicit primary data from 168 farmers, randomly selected from
the three agricultural zones of the state. Analysis of the data were done using multinomial
logit model, partial budget analysis Duncan‘s Multiple range test and descriptive
statistics. Four erosion control practices were used by the farmers: Multiple cropping, as
indicated by 41% of the respondents, Construction of Bonds, 20%, Ridging across the
slope, 18% and Cover cropping, as indicated by 21% of the respondents. The Partial
budget analysis showed the net-benefits of each of these erosion control practice as N393,
953.88k for Multiple cropping, N26, 115.30k for Construction of Bonds, N33, 741.66k
for Ridging Across the slope and N891.10k for Cover cropping. 7.36 (Multiple cropping),
1.59 (Construction of bonds), 1.14 (Ridging across the slope) and 1.10 (Cover cropping)
were shown as the profitability index for the erosion control practices. Duncan‘s
comparison test showed that there was statistically significant difference in the means of
net-benefits of erosion control practices at 5%. The Multinomial logit Regression analysis
indicated a seemingly low explanatory powers of the factor as reflected by Pseudo- R2 of
0.2449, but this is not uncommon in cross sectional analysis. The overall goodness of fit
as reflected by prob>Chi2 was however good (<0.0000). The age of the farmers
negatively and significantly affected the farmer's probability of using Cover cropping at
1% level of probability, all in comparism with Construction of bonds. Household size
positively and significantly affected the farmers probability of using Multiple cropping
and making ridges across the slope at 1% probability level. The Likert rating scale
technique showed six very serious causes of erosion on the farmlands. These were
Rainwater (mean = 2.42), Deforestation (mean = 2.26), Soil type (mean =2.49), Slope of
the farm (mean =2.37), Poor road construction (mean =2.35), Indiscrimate house
construction (mean =2.16). It also indicates two serious causes of erosion which include;
Population density (mean =1.99) and Poor farming system (mean =2.01). Others such as
Quarrying of sand (mean =1.64), Crops that attracts human traffic (mean =1.42), gods
(mean =1.16), Overgrazing (mean =1.74), and Cattle hooves were shown as not serious
causes of erosion by the Likert rating.
It is therefore recommended that government should encourage farmers with incentives
to cope with the challenges of erosion for a sustainable Agriculture and Environment.
1
CHAPTER ONE
INTRODUCTION
1.1
Background of the Study
A dramatic acceleration in population growth has taken place in sub-Saharan
Africa since the 1960s (World Bank, 2006). The increasing demand to feed this growing
population has lead to resource use intensification (Junge, Birte, Abaidoo. Chikoye ,D.
Alabi ,T. and Stahrand Karl,(2006). and Non- adaptable land use practices which lead to
soil degradation (Hudson, 1995). In sub-Saharan Africa, soil degradation has already
become the most critical environmental problem (Mbagwu,Lal, and Scott,(1984) Eswaran
,,Lal and Reich,( 2001). Soil erosion is one manifestation of soil degrading processes that
results in reduced soil quality and productivity (Akamigbo, 2001, Morgan, 1995, Lal,
2001). There is an urgent need to combat the accelerating trend of soil degradation, to
maintain soil productivity and to contribute to the food security of current and future
generations (UNEP, 1997).
Ecological disasters rank high among factors which encourage inefficient
utilization of resources in Nigeria and limit the country‘s development potential. They
occur in various forms but typically include droughts, soil and wind erosion, flooding, oil
pollution and bush fires. Soil erosion is one of the most important physical problems
affecting our development in this part of the world today. Apart from the fact that it
constitutes a menace to the environment and its destruction of our infrastructures-high
ways, big structures etc, it creates a major problem in our agricultural soils, thereby
interfering seriously with the mass food production campaign. We cannot afford to overlook these problems created on our soils by soil erosion because there is no real evidence
that we may some day detach our lives from the soils. It is the soils that sustain us
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because soils are the foundation of our worldly goods-a basic wealth upon which our
existence as inhabitants of the earth depends (Akamigbo 1987).
The web definition of erosion says it is the wearing away of the earth‘s surface by
running water, wind, ice, or other geological agents, processes, including weathering,
dissolution. Akamigbo (1988) defined erosion as a systematic removal of soil, including
plant nutrients, from the land surface by the various agents of denudation. According
Ofomata (1988), soil erosion can be regarded as merely a geomorphologic process,
whereby the surface layer of weathering rock is loosened and carried away by wind or
running water and a lower horizon in the soil is exposed.
Soil erosion occurs in several parts of Nigeria under different geological, climatic,
and soil conditions. The degree of occurrence varies considerably from one part of the
country to the other. Soil erosion occurs all over southeastern Nigeria. The incidence of
soil erosion in southeastern Nigeria especially Enugu state is not new, as it has formed a
subject for serious consideration since the beginning of this century. For instance, the Udi
forest Reserve was created in 1922, followed by an Anti-Erosion plantation, also at Udi,
in 1928 (Sykes, 1940), all aimed at combating the nefarious effects of soil erosion as
highlighted by the general review of the state of soil erosion in Nigeria by late Sir.
Dudley stamp in 1938. Stamp‘s review was followed by the special study of the
phenomenon by Grove (1951) in part of former Eastern Nigeria as well as by Ofomata in
some greater detail in parts of southeastern Nigeria (Ofomata, 1964, 1965, 1966, 1967,
1973, 1980, 1981a, 1981b, 1981c, 1982, 1984, 1985a, 1985b and Stone, 1996). Soil
erosion is a major limitation to sustainable production in most farmland of Africa (Lal,
1995) in general and southeastern Nigeria (Enugu State) in particular. It ranks as one of
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the most serious problems on agricultural lands, threatening large populations with
starvation (Oti 2002). Studies have shown that soil erosions is by far the most severe
hazard affecting the lands of Nigeria, ravaging all of its bio-climatic regions as rill, sheet,
and gully erosion (Ofomata 1964,1980,1982,1984a, and b, Ologe, 1971: Oganuga 1978, ,
Anon, 1988). Soil erosion causes the loss of a tremendous amount of valuable soil, (Kio
and Okorie (1986). It has been estimated that about 30 million tones of soil are lost
annually throughout the country with the eastern states losing over 15million tones,
(Onyeagocha, 1980, Okorie and Adeola, 1985). The depletion of agricultural land
resources occurs through different forms of land degradation namely, leaching of
nutrient, erosion by water which has led to devastating gullies in some parts of the
country especially southeast, drought and wind erosion resulting in desert encroachment
in the northern parts of the country and wastage of land by flood and coastal erosion,
(Akamigbo, 2006). As soil becomes depleted by water erosion, people attempt to move to
other more productive land. Eventually, when there is no more land available they are
forced to adapt themselves to smaller amounts of food which require harder work to
grow. This condition lead to malnutrition and hopelessness. (FAO 1965). Erosion, as an
environmental hazard has numerous adverse economic effects on the lives and livelihood
of people. Generally it results in a degradation of the environment, and reduction in land
area available for habitation, agriculture, industry, recreation, road construction, as well
as loss of soil fertility. Furthermore, erosion also leads to pollution and blocking of
waterways, loss and destruction of social centers, and social amenities. (Ezebube, 1989
and Akamigbo, 1999). Soil erosion also leads to pollution and blocking of waterways,
loss and destruction of social complex process that depends on soil properties, ground
slope, vegetation, and rainfall amount and intensity (David, 2007).
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The major environmental cause of soil erosion in southern Nigeria is rainfall with the
mean annual rainfall reaching about 3000mm in some parts and with rainstorms often of
long duration and intensities which may be up to 200mm-1, it would be expected that the
erosivity factor plays a dominant role in the soil loss problem (Obi and Asiegbu, 1980).
Controlling erosion on productive land must usually be done while growing crop.
Therefore many control measures are closely related to ordinary methods of agriculture.
The common ones are land use, cropping systems, cover crops, fertilizers and
manures, ridging across the slope, construction of bonds, grassing of water ways, hedgerow planting / vetiver grass and tillage practices (FAO, 1965., Akamigbo, 1988, 1998.,
Ofomata, 1988., Chude, 2005., Lal 1995., ENADEP, 2007). Management of soil for
water and wind erosion control is based on sensible soil conservation practices. The
majority of these practices are recognized components of good soil, crop, and water
management for effective erosion control. It is important to maintain good soil structure,
protect the soil surface by adequate crop and residue cover, and use special structural
erosion control practices where necessary. These factors often control both water and
wind erosion. Not all erosion control practices will fit into every farm management
scheme. However, each erosion problem can be remedied by choosing one or more of the
remedial practices appropriate to the problem. (Stone, 1996). Of all types of erosion the
most pernicious and serious on the farmland in the southeast is the sheet erosion. It
causes the gradual but significant losses of soil particles and mineral nutrients which are
carried away in surface run-off during rainfall or blown away as loose particles by strong
winds in drier areas. The activities of man and other land animals, which destroy
vegetation cover, predispose the soil to accelerated sheet erosion. For instant, the hooves
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of cattle in any fragile soil environment pulverize the soil as they move and render the
soil susceptible to both wind and water erosion, (Akamigbo, 2006).
1.2 Problem Statement
Farm land erosion poses a very serious set back to farmers in Enugu state and the
extent of the spread and damage have reached an alarming proportion that if efforts are
not intensified to remedy the ugly situation, it could cause untold hardship and put the
communities in a state of jeopardy. It has been estimated that available arable lands in
the states of the southeastern Nigeria have been reduced by 50% as a result of erosion
(Braide, 1982). Erosion leads to the pollution and destruction of the environment. Rural
water supply from streams is also constantly being polluted by heavy sediment load,
thereby adding health hazard to the problem of damage to infrastructure (Akamigbo,
1999). Some of the most ravaging erosion related environmental hazards are found in
many parts of the southeast, especially Anambra, Enugu and Imo states (Ofomata, 1985,
Akamigbo, 1988 and Ogbukagu, 1986). Many farmlands from which majority of the
households earn their livelihood are especially affected; a situation which has led to thigh
population pressure on the available land (Onuora, 1985, Ezebube, 1989, and Akamigbo
1999). This condition according to them have inflicted great losses in the production
potentials, crop land, crop quality, biodiversity, genetic resources as well as excessive
field fragmentations.
The economic cost of erosion is very difficult to quantify, but it is definitely very
large, Huge sums of money are spent each year repairing damage caused by erosion or
reinforcing existing structures and land against erosion, (Akamigbo, 1999).
Money that should be used by rural farmers in Enugu state for solving their family
problems is spent on erosion control.
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Erosion control is usually expensive and many efforts have been made by
successive governments to control erosion in southeastern Nigeria but not much success
have been achieved. This could be attributed to lack of proper understanding of the
techniques involved in handling erosion control. Agro-engineering findings indicate that
farmers in the rural southeastern Nigeria apply many techniques to conserve soil, control
erosion and prevent soil degradation. (Onuoha, 1985 and Ofomata 1982). Young (1989)
states that the costs or labour requirements of physical erosion control works necessary to
control run-off by such means as bunds and terraces were commonly found to be
expensive. ―Conservation farming‖ or ―integrated land use‖, the emerging farming
systems approach to environmental conservation, has been practiced by Nigerian farmers
for a long time (Okoye, 2001).
Young (1989) advocated the use of simple methods of erosion control such as
mulching, bunding, and cover cropping, which are within the capacity of the farmers to
establish and maintain, and endorses external support for sound traditional farming
practices. Despite the awareness of these traditional techniques and management actions
of the local farmers to control erosion and protect the environment, they have remained
largely under studied, unexplored and neglected especially with regards to the economic
evaluation of these indigenous techniques. (Reiji 1990, Eboh 1991).
Although, Utazi (2002) carried out an economic study of farmland erosion control
practices in Imo state where he identified the different erosion control practices used by
farmers in the area and determined the cost benefits of erosion control practices, he failed
to describe from the farmers perspective the possible causes of erosion on the farmland as
well as determining the socioeconomic factors affecting the farmers use of a particular
erosion control practice. Another missing value is the difference in location of the study.
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This study therefore aims at addressing these missing links in Enugu state.
1.3 Objectives of the Study
The broad objective of this study was to conduct an economic analysis of
farmland erosion control practices in Enugu State. The specific objectives are to;
i.
identify and describe the erosion control practices (or combination of practices)
applied by farmers in the area.
ii.
determine the net benefit of erosion control practices.
iii.
determine the socioeconomic factors affecting the farmer‘s use of a particular
erosion control practice.
iv.
identify from the farmer‘s perspective the possible causes of erosion and extent of
cause on the farmland.
1.4 Hypotheses
In line with the specific objective this research was guided by the following null
hypotheses;
1.
There is no relationship between the socioeconomic characteristics of the farmers
and the type of erosion control practices used.
2.
There is no significant difference between economic benefit of different erosion
control practices by the farmers.
1.5 Justification of the Study
The study will provide information to farmers on the net benefits of farmland
erosion control practices for increased crop productivity and food security. Measures
aimed at controlling farmland erosion will to a large extent save soil fertility, economic
trees and crops and farmland from being devastated. The knowledge of the economics of
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erosion control measures will guide the policy makers in quantifying the control practices
for future planning.
On the other hand, information on the economic analysis of farm land erosion
control practice will equip the Environmental Protection Agency (EPA),in formulating
appropriate environmental related policies in order to ensure environmental
sustainability. Achieving certain standards of erosion control, will provide information
about the value given to land in the market to erosion control, what will help investment
decision.
Finally, other researchers that are interested in searching for solutions of the
devastating effect of erosion will be assisted with the information that will be provided in
the study. It will invariably provide information on how best to increase the farm land
value in other to consequently increase its productivity and alleviate poverty.
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CHAPTER TWO
2.0 LITERATURE REVIEW
The literature was reviewed under the following captions:
2.1 Concept of soil erosion
2.2 History of soil erosion
2.3 Mechanism of soil erosion
2.4 Economics of soil erosion control.
2.5 Factors responsible for erosion in Enugu state.
2.6 Classification of erosion
2.7 Erosion control
2.8 Problem and effects of erosion
2.9 Documentation of erosion site in Enugu state.
2.10 Review of existing erosion control practices
2.11 Theoretical framework
2.12 Analytical framework.
2.1 Concept of Soil Erosion
Several definitions has been given to erosion as a concept from different
perspective.
Definitions of erosion from the web: The wearing away of land or soil by the action of
wind, water or ice.
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The wearing away of land surface by water, intensified by land-clearing practices related
to farming, residential or industrial development, road building or logging. The gradual
diminishing of land or soil as a result of the action of water wind rain etc.
‗ Erosion‘ comes from erodere, a Latin verb meaning ― to gnaw‘ Erosion gnaws
away at the earth like a dog at a bone. This has given rise to pessimistic view of some
writers who see erosion as a leprosy gnawing away the earth until only a whitened
skeleton is left (Roose1996). Holy (1982), opined that erosion is manifested by the
deterioration of soil surface affected by exogenous forces. According to Mumel (1992),
erosion is the removal of surface material from the earth crust, primarily soil and rock
debris and the transportation of the eroded materials by natural agencies from the point of
removal. Goudre (1990), saw erosion as the most destructive process that acts to reduce
productive farmland. Wood (1995), defined erosion as the wearing away of the soil
surface by running water, wind, ice or other geological agents, including such processes
as gravitational creep, detachement and movement of soil and rock fragments by water,
wind, ice or gravity. Dike (1995) stated that erosion is a natural phenomenon which is the
wearing away of the earth‘s surface by water, ice or other natural agents under natural
environmental conditions. Lal (1990) defined erosion as the washing and blowing away
of the top soil by running water and wind respectively. Middleton (1990) defined erosion
as detachment and transportation of soil particles by water and wind.
Erosion is a natural process which indeed wears down all mauntains ( also
referred to by the English school as the denudation rate, which is the lowering rate of the
soil level), however, at the same time erosion enriches valleys and forms the rich plains
that feed a large part of humanity, (Roose, 1996). It is therefore not necessarily desirable
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to stop all erosion, but rather to reduce it to an acceptable or tolerable level.Ofomata
(1988) categorized the factors of soil erosion in south-eastern Nigeria into two
components: Physical (geological or natural) and Anthropogenic (human or accelerated).
Close study has, however, revealed that the human component in soil erosion is often
exaggerated while the effects of the physical component are usually underestimated
(Ofomata, 1965 and 1978)
Roose(1996), stated that Normal or geological erosion (morphogenesis) is
generally defined as the process that slowly shapes hillsides, allowing the formation of
soil cover from the weathering of rocks and from alluvial and colluvial deposits
(pedogenesis). Roose (lbid) on the other hand, opined that erosion accelerated by human
activities, following careless exploitation of the environment, is 100 to 1000 times faster
than normal erosion.
Oradiegwu (1980) grouped soil erosion into two classes, gully and sheet erosion.
His classification was based on the depth to breadth ratio to the surface affected. When
the depth of the erosion is negligible in relation to its breadth, the erosion is referred to as
sheet erosion. On the other hand, when the depth of the erosion is significant in relation
to its breadth, it is called gully erosion. Whenever there is surface run –off, there must be
sheet as well as linear erosion. According to Forth (1984), the soil carried away by
erosion frequently ceases to be of value in crop production. Furthermore the remaining
soil denude of the surface or pillow layer is much decreased in productivity, in comparing
the nutrient losses through erosion and its uptake by plants, the loss of nutrients by
erosion even on a 4% slope, may easily exceed the removal of nutrients by crops
12
occupying the land. Arakeri, (1959) also stated that the fertility losses by erosion have
been estimated to be 20 times greater than losses through the crop removal or leaching.
Ofomata (1981) evaluated the impact of erosion upon local environmental
knowledge and indigenous systems of management and organization. His general
consensus is that indigenous soil and water conservation practices forms an indispensable
starting point for the development of counter erosion projects.
The case of studying traditional erosion prevention and control practices in
southeastern Nigeria, is self evident. The failure of ―top down‖ projects have led to
increased call for ―bottom top‖ projects that would be farmer based, cost effective and
locally sustainable (FDALR, 1990).
2.2 History of Soil Erosion.
Erosion is an old problem. From the time land emerges from the seas, it is lashed
by the forces of wind, waves and rain, (Roose, 1996). Erosion is as old as agriculture,
(Amechi ,1997 and Edward, 1993). The Nigerian civil war 1967-1970 did not only take
its toll of human lives but left many plantations, forest reserves and farmlands devastated
and unprotected. Massive refugee camps usually constructed under thick forest covers
turned into gulling areas even when the inmates were still in settlement. The operations
of the ‗land army‘ by farming on every available land space created an additional
favourable environment for serious sheet and rill erosion, both of which were precursors
to many of the present gullies in Anambra and Enugu state, (Akamigbo, 1988).The
decisive epoch of the development of soil erosion according to Holy (1980) began when
man settled down and began turning pasture land into farms. The intensive exploitation of
13
the land disturbed the natural soil vegetation cover and exposed the surface to the effect
of erosion agents and introduced such forms of agriculture that did destroy the land.
The present land mass known as Anambra and Enugu state had been bedevilled
by the menace of gully and sheet erosion long before the arrival of the British colonial
Government. Gullies by their nature are more perceptible and spectacular. Those at udi,
Nanka, Adazi, Alor, Oraukwu and Agulu are older than 150 years, predating any living
human being in the areas concerned. The efforts of the colonial government in stabilizing
some of these degraded areas at Enugu and Udi (the capital territory of former Eastern
Nigeria) dated back to the 1920s. (Akamigbo, 1988).In 1928, erosion control work was
started in Udi by treating the badly eroded areas with simple mechanical devices
combined with planting of seeds of Actio
barteri, Anacardium occidentale,
Erythrophleum svaveolens and Pentaclethra macrophylla, (Okafor,1986).
As early as 1944, the geographic harmony had clearly realized why ―Africa is a
dying land‖. It was dying as a result of the destabilizing methods of colonial systems
which intensified soil use, hastened removal of assimilable nutrients and mineralization
of organic matter, and pushed the indigenous people on the poorest and most fragile land,
reducing the length of fallow periods (Roose, 1996).
During the Biafran war, the cohesionless soil mass of southeast was subjected to
motar bombardments in addition to series of deep trenches which were not refilled. It was
not surprising then that the first environmental problem experienced by the people of
Anambra. Enugu, Imo and Akwaibom states immediately after the civil war was the
upsurge of serious sheet and gully erosions. (Akamigbo,1988).
14
The deceptive sheet erosion was more devastative and crop yield was rapidly
decreasing. The cries for help spread quickly from one village to the other. The then
federal military Government in 1974, intervened by signing a contract with an Italian
firm of consultants, technical S. P. A. Rome and Nigeria techno Ltd Lagos to undertake a
per-feasibility study of the parts of the then East central state in order to determining the
cause and seriousness of soil erosion in the state.(Akamigbo, 1988).
Soil erosion menace in Enugu state has therefore continued unabated to take its
wants toll of indispensable soil and water resources, civil infrastructures, property and
life and has placed agriculture and the entire environment in a very serious jeopardy. The
situation continues to assume more catastrophic dimensions as the rains come and go
every year.
2.3 Mechanism of Soil Erosion.
Soil erosion requires energy, and the energy of an intense rainstorm is
tremendous. The energy from raindrops packs the bare soil surface and disperses soil
aggregates. The dispersion products (Mostly clay) are washed into surface voids and
along with the packing done by the raindrops form a film at the soil surface. The
permeability of this film is very low, and most of the water begins to run off in sheets
after it is formed. These sheets of water have virtually no carrying capacity for soil
because they are so thin. However, when the energy of raindrops is added to these sheets
in the form of turbulence, the carrying capacity is increased manifold. The dispersed
material released from the aggregates is carried off resulting in so-called sheet erosion,
which is responsible for most of the erosion from crop land soils, (FAO, 1965).
15
Holy (1980), stated that erosion is manifested by the deterioration of soil surface
affected by exogenous forces, especially water, ice, wind and man as the significant
anthropogenic factor. He went further to state that the disturbance of the soil surface is
accompanied by the removal of detached soil particle by the forces of kinetic energy of
the erosion agent namely water and wind and the depositions of these materials with a
decrease in the energy.Erosion is basically an interactive process. The interactors are the
failing raindrop or flowing water on the land, and the soil on the other. The energy of the
raindrop or flowing water has the ability to detach and transport the soil particles. This
ability is referred to as Erosivity of the water. On the other side of the interaction is the
soil, whose particles may or may not yield to a given level of erosivity. The measure of
the ease or difficulty of detachment (and transport) of soil particles under erosive
influence is referred to as Erodability. Therefore for erosion to occur, the water must be
erosive and the soil must erodable, (Akamigbo 1998).Lal (1986) described soil erosion by
water as a work process involving two phases; detachment of soil particles and their
transport. He stated that soil detachment involves the removal of transportable fragments
of materials from a soil mass by raindrop impact or shearing forces of overland flow. On
the other hand, transport or entrainment of detached primary or secondary particles occur
through splash and overland flow.
The process of sheet erosion consists of two essential component; rain splash
erosion and surface wash. Rain splash erosion is due to the impact of raindrops on the
ground surface. As a rain drop hits the soil, it tears loose particles of soil and kicks them
into the air. Most of the soil particles land away from the point of impact with more of
them landing on its down slope than on its upslope side. Thus, the net result is the
16
downward slope translocation of soil particles. The process is also important in aiding
surface wash by loosening the soil and making the particle available for transportation.
Surface wash is the process whereby water running down the slope as a turbulent sheet
removes particles of soil and carries them away. This surface runoff occurs during and
immediately after rain storms in which the rainfall intensity exceeds the soils infiltration
capacity (Ologe, 1986).Raindrop on striking the soil surface, expends its kinetic energy in
detaching soil particles. According to Wischmeier (1959), the erosion generating power
of the raindrop is the product function of the raindrop energy and the maximum 30minute rainfall intensity.
Running water is the main agent of erosion in the Enugu state and the process of
erosion depends on the manner in which runoff is organised over space. The mechanics
of erosion in the area also vary with the types/process. Sheet erosion occurs where runoff
is unconcentrated but rather flows as a thin sheet over the entire surface or over a good
proportion of that surface. Gully erosion occurs where runoff is concentrated along
definite channels. The gullies lengthened by headward erosion, also known as head-scarg
retreat and widens through basal sapping leading to the collapse of materials on gully
walls in the form of sliding and or slumping, (Ofomata, 1986).
Rain tends to run off surface of the soil in deforested or over-grazed areas,
thereby removing the top soil. Deforestation and over-grazing remove the original
vegetation which breaks the fall of rain and also supplies the topsoil with the humus
which allows rapid absorption of water. Rain which falls on unprotected soil tends to clog
the normal openings of the soil with bits of silt, so that the run off is increased. Run off is
the part of rainwater which does not sink into the soil, but flows away over the surface to
17
steam or rivers or oceans, (Akinsanmi, 1975). The wind exercises a pressure on solid
particles in repose. This pressure is exerted above the centre of gravity on the surface
exposed to wind and is opposed by a friction centred on the base of the particles. The two
forces combined tend to lock particles (0.5 to 2mm) and make them roll, (Roose, 1996).
Moreover, the difference in speed between the top and bottom of particles means
that they are drawn upwards. The lighter particles rise vertically until the gradient of
velocity is too low to bear them, at which point, they fall back pushed by the wind,
following a sub-horizontal curve. As they fall, these grains of sand transmit their energy
to other grains of sand (as in a game of bowls) or degrade loamy clay aggregates,
releasing dust (Heusch 1988).
2.4 Economics of Erosion Control
It has become very clear in recent times that soil conservation schemes has
continued to reduce the amount of soil carried away by erosion and can answer the needs
of farmers in tropical region. Indeed, experts have been saying for a long time that soil
has to be conserved so as to maintain the productivity of land; thus the title of the fifth
ISCO conference (Bangkok, 1988) was ―land conservation for future Generation‖.
Farmers (not always of their own volition) have undertaken to devote considerable efforts
to schemes to control erosion on their land, but have been disappointed to see that their
land still deteriorated and crop yields still fell. The erosion control structures imposed
(drainage ditches, diversion channels, bunds) have often reduced the arable land area (by
3% to 2%) without any equivalent improvement in the productivity of ―protected‖ plots.
If farmers are to be motivated, it is not enough to keep the soil in place, water must be
18
managed and soil fertility restored in order to see a significant increases in yields from
these tropical soils, the majority of which are already very poor (especially tropical
ferralitic and ferruginous soils that are sandy on the surface) (Roose, 1996).
Soil erosion is a major environmental threat to the sustainability and productive
capacity of agriculture. During the last 40years nearly one third of the world‘s arable land
has been lost by erosion and continues to be lost at a rate of more than 10 million hectares
per year. With the addition of a quarter of a million people each day, the world
population‘s food demand is increasing at a time when per capita food productivity is
beginning to decline (David et al 2007).The brain behind conserving the soil is for
environmental sustainability and the survival of mankind. The implacable nature of soil
does not permit us to have a purely economic view point of soil conservation. Every
piece of land has a certain market value that is related to its present and potential
productivity. But actually, the intrinsic value of land is much greater than money, it lies
on its ability to feed and clothe man for countless centuries. This can not be expressed in
monetary terms (kohnke and Bertrand, 1959). The most important characteristic of land
resource is the relationship between the amount of soil lost and the land productivity
(Mbagwu, 1986).Gully erosions processes cause damage to many branches of the
economy of a nation and much of these damages especially the social consequences is
difficult to express in numerical values (Holy, 1980). One of the major contemporary
challenges facing environmental scientists and policy makers is the growing enormity of
resource degradation and related soil erosion problems in part of sub-Saharan Africa.
These challenges becomes more glaring considering that the region loses about six tons
of soil to erosion each year (steri-Younis, 1986).
19
In Nigeria, some of the most devastating erosion related environment hazards are
found in many parts of the southeast especially Anambra, Enugu and
Imo States
(Ofomata 1981 and Ogbukagu, 1986). Over half of the total land area is believed to suffer
different forms of erosion ranging from mild sheet wash, severe sheet wash to gulling
processes. Sheet erosion of the humose topsoil causes fertility decrease because the
topsoil contains most of the nutrients needed by the plants to grow. The cost of
replenishing these nutrients is quite high and when they are not replenished, poor crop
yields results (Akamigbo, 1999). According to Risser (1985), erosion is a massive
hidden‖ cost on the economy of any community and as erosion increases, so do food
costs. Farmers must then apply more chemicals to the land in order to compensate for the
fertility loss caused by erosion and must spend more money for tillage activities because
eroded soils are more compacted and difficult to till.
Conservation of soil and water has many benefits as enumerated by Winpenny
(1991)

Viz,
Avoided losses in crop yields from soil erosion, loss of soil depth and fertility, or
loss of land through gully erosion; alternative savings in fertilizer to maintain
yields on eroded soils.

Value of wood production from tree planting (timber, poles, fuelwood, forage,
fruit etc);

Value of enhanced livestock productions from restored or improved pasture,
better use of crop residues, or from fodder, trees (meat, milk, wool, dung)
20

Increased crop yields from ecological benefits of a managed mixed regime
(increased soil organic matter, more soil moisture retention, shading etc).
Farmland erosion control in Enugu state is crucial in order to avoid the
devastating consequences of soil and water degradation.
2.5 Factors Responsible for Erosion in Enugu State.
According to Onyeagocha (1980), the agent of soil erosion in Anambra and Enugu
state is water and Ude,N.C.,Uzuakpunwa,A.B.and Ezeike,G.O.I. (1980) agreed that
rainwater in any form is the most active agent causing erosion in the area but the causes
of .erosion in the old Anambra state were summarized by the form of consultants (Niger
Techno Ltd. And Technical International General Engineering, 1974) as concentrated run
off water within lithological units consisting of sands and sand-stone bed rocks covered
by a thick porous weathered layer, the disappearance of rain forest vegetations and civil
anthropogenic activities. Besides, these causative factors, other factors that play
significant role in soil erosion in Enugu and Anambra include topography (relif \slope),
climate and surface material (Ofomata 1985). Others are population density and some
.sociological life patterns such as land tenure system and local belief system of the
people.
Anthropogenic activities which either initiate or aggravate soil erosion in the
study area include poor road construction, indiscriminate house construction across
natural drainage routes, quarrying of sand and gravels, bush burning, indiscriminate tree
felling and poor farming techniques. Urbanisation, industrialization, unplanned location
of borrow sites and poor sanitary disposal measures also render the soil prone to soil
21
erosion (Akamigbo, 1988). Human erosion action is made manifest on the earth‘s surface
through his agricultural activities, especially through the clearing of the original
vegetation or the periodic forest regrowth. These activities in southeastern Nigeria
particularly in Enugu state have largely succeeded in replacing the former rain forest by
grassland (.derived) savannas. When man destroy the vegetation, it affects the soil very
adversely because, first, it interrupts the building up of organic matter, and secondly it
accelerates the decomposition of the humus inherited from the former vegetal cover.
This humus affects both the permeability of the soil and the rate at which water infiltrates
through it. Indeed it is thought that the humus content of soils explains in part the
generalized nature of the runoff in an area. (Ofomata, 1988)
Erosion is as old as agriculture. It is a process which is continually transforming
the earth‘s surface and it is initiated by natural forces and intensified by human activity
which has been significant in the recent period as man began to step up the exploitation
of natural resources (Amechi, 1997 and Edward, 1993). Whitlow,(1987) and
Aneke,Obuji,and Nwafor,(1982), opined that erosion is due to. growing pressure on the
land from human and livestock populations while Gowon (1981) stated that erosion in
Nigeria is .caused by careless use of land for agriculture and other purposes.The common
farming practices that lead to soil erosion are; the ploughing of land up and down the
slope, clearing a piece of land by burring, continuous
farming and cropping,
deforestation of forest especially on the higher slopes and the overgrazing of grasslands
especially by goats and sheep (Middleton, (1990) and Lal (1990). As long as vegetation
remains, there can be little if any erosion, because the roots of the plants bind the soil
particles together and the vegetation itself protects the soil from the action of wind and
22
rain (Pitman, 1987).Lal (1990) noted that rainfall leads to leaching and runoff which is
the central agent in soil erosion system. When runoff is concentrated, it gives rise to gully
erosion and when it is unconcentrated it gives rise to sheet erosion.
According to Nigeria Institute of Social and Economic Research (NISER, 1988),
the choice crop that are labour intensive or attract human traffic may cause severe soil
erosion. For instance cashew tree (Anacardium occidentale) was introduced in some
gullied areas in the southeastern Nigeria including the Agulu-Nanka gully axis, for the
purpose of reafforestation and stabilization of the gullies. Cashew suppresses .many
undergrowths and encourages overland flow and erosion. Manual harvesting of cashew
fruits and its transport action causes soil compaction and encourages gully erosion
(Okafor, 1986).
Going by Gobin,Campling,Deekers,Poesen,and Feyen,(1999), biophysical and
participatory research methods were combined to examine factors contributing to soil
erosion at field plot, village and regional scale on the sandstone dominated Udi-Nsukka
cuesta in southeastern Nigeria. At field plot scale, the properties of seven pedons were
related to soil erodibility. Very high infiltration rates measured with a double ring
infiltrometer and permeameter, were not in accordance to reported runoff and soil loss.
The effect of groundcover and canopy height was incorporated into rainfall erosivity for
plots under cashew, oil palm dominated forest and secondary natural vegetation.
Cropping systems and field management practices were compared for different positions
along a toposequence transversing the plateau and escarpment of the Udi-Nsukka cuesta.
Soil loss, calculated by a modified version of the universal soil loss equation, was 10 to
100 times higher on escarpment than on plateau plots. According to Gobin
23
Campling,Deekers,Poesen,and Feyen
(1999), Ravine and gully formations seemed
influenced by a combination of infrastructure, geohydrology, topography, vegetation and
land use.
The relationship between climate and soil erosion is fairly well known and for
south eastern Nigeria, especially Enugu state, rainfall and soil type constitutes the
dominant sub-factor. In the environment of south-eastern Nigeria, the rains come in the
form of intensive, violent showers of short duration, especially at the beginning and end
of rainy season. The erosive capacity of raindrops seems to result from three factors, the
amount and intensity of rainfall, the diameter of the drops and the velocity of the drops as
they strike the soil. Rainfall gives rise to runoff which is the central agent in the soil
erosion system and the nature of the concentration of the runoff leads to sheet and gully
erosion as the case may be (Ofomata, 1985,1988).The nature of surface materials
influence the rate of infiltration and thereby, of slumping and/ or sliding. Surface
configuration (relief/ slope) aids runoff, sheet erosion and gullying. Sheet erosion is
expected to be more common over fairly uniform and gentle slope, while gullying is
expected to be more characteristic of stepper slopes (Akamigbo(1999) and Ofomata
(1988).
In spite of the important role of the physical factors discussed so far, there can be
no doubt that almost unique dimension which soil erosion has attained in south eastern
Nigeria is related in very direct way to the lithological composition of the soils of the
area. This derives from their parent materials which are mainly soft sandstone formations
of cretaceous and tertiary age. Under the intensive chemical action resulting from the
high temperature and humidity conditions, of the area, these sandstone, mostly false-
24
bedded and with a high Iron content, weather down to what are generally referred to as
―red earths‖. Owing to the intensity of the chemical weathering, the red earths give rise to
soils which show a conspicuous absence of pebbles. Nonetheless, the predominant
component of the soils is sand, especially medium, grained sand (0.2 t0 0.5mm)
(Ofomata, 1988).
2.6 Classification of Soil Erosion
Soil erosion in south-eastern Nigeria can be classified into two major categories;
physical (geological or natural) and anthropogenic (human or accelerated) (Ofomata,
1988). The type of geology, soil, topography and climate of Enugu state predispose the
physical setting of the state to erosion of all types. Sheet erosion and gully erosion are
most devastating and prevalent (Akamigbo, 1988).
Several types of erosion exist in the study area. They include;
A. Natural erosion: Erosion is considered to be natural when the earths surface is being
removed by water, ice or natural agents under natural environmental conditions of
climate, vegetation and so on, undisturbed by man. This is synonymous with geologic
erosion, and its effect is not disastrous (Akamigbo 1986and 1998).According to
Chude(2005), natural erosion takes place all the time and is part of the natural process in
the formation of the landscape. This type of erosion is not a problem in agriculture
because as the soil is removed from a spot, some soil is being formed on the same spot.
B. Normal erosion: This is the gradual erosion of land used by man which does not
greatly exceed natural erosion. When we farm, it is the purpose of good soil conservation
25
and management that the erosion that occurs in the farm land would not exceed normal
erosion. The loss here is very minimal (Akamigbo, 1986and 1998).
C. Accelerated erosion: This is the erosion much more rapid than normal natural
geological erosion. This is primarily as a result of the influence of the activities of man
or, in some cases, of animals and other factors (Akamigbo ibid and ibid). Man, made
erosion is the type of erosion which the quantity of soil lost and the rate of soil loss is far
higher than the natural erosion. It is induced by human activities such as deforestation,
bush burning, cutting of hills, harvesting of stones and sand etc and is therefore referred
to as anthropogenic (Chude, 2005).
D Splash Erosion: This is the process of the detachment of soil particles by raindrops.
This occurs when rain-drops hit on an exposed soil surface free from vegetative cover
and the surface is wet. On some soils, a very heavy rain can cause a soil particle to rise or
jump as high as 2ft above the ground and move up to 5ft horizontally. In terms of
quantity, as much as 224t/ha can be splashed up by a very heavy rainfall. Splash erosion
even on cropped land is evidenced by the presence of soil particles on the underside of
green vegetables. Splash erosion is directly related to the raindrop size and the type of the
soil structure. The defaced particles are removed by surface runoff as sheet erosion
(Akamigbo 1986 and 1998).
E. Sheet Erosion: This is the removal of a fairly, uniform layer of soil from the land
surface by runoff water, and other agents. This type of erosion is most dangerous for our
agricultural lands as it carries away the humus top soil. It often goes on unnoticed due to
its gradual, constant and uniform action. It renders the soil infertile and its disastrous
26
influence lies in the fact that it is not easily perceptible by the farmer. It may finally result
in a complete removal of the arable parts of the top soil. Through this action of sheet
erosion, the topsoil is gradually swept clear of its finer elements and plant nutrients, and
only coarse, infertile materials are left behind (Akamigbo 1986 and 1998 and Chude,
2005).
UNEP (2008), opined that sheet erosion is a phenomenon whereby a large area of
surface soil is lost by almost even blanksheet flows of surface or mear surface water.
Sheet erosion occurs nation wide, but it is last perceived because of its ―deceitful‖ slow
progress. It slowly removes the surface soil layers by rainfall runoff down slopes,
producing a devastating effect on agriculture.
F. Rill Erosion: This is an erosion process in which numerous small channels of only
several centimetres in depth are formed. It occurs mainly on recently cultivated areas
after a rain event. Rill erosion occurs when soil is removed by water from little streamlets
that run through land with poor surface draining. Rills can often be found in between crop
rows. Although its effects can be easily removed by tillage, it is the most often
overlooked and if it is not filled up, it could develop to gully erosion. Farmers can easily
handle it (Akamigbo 1998)
G. Gully Erosion: This is an erosion process whereby water accumulates in narrow
channels or rills or crevices and, over short periods, removes the soil from this channel to
considerable depths ranging from 30 to 60 centimetres to as much as 23 to 30 meters or
more. Gully erosion unlike sheet erosions is more obvious as it makes a remarkable
impression on the surface of the earth. The physical loss of the land is visibly manifested.
27
Gullies can grow in both up hill and downhill directions. A heavy rainfall can enlarge a
small rill into a big gully overnight. Gully erosion is infact another term for accelerated
soil erosion and once it is formed it difficult to stop it from growing and it is very
expensive to rehabilitate the land. The process, in most cases, is related to the activities of
man, especially those connected with the destruction of vegetation cover (Akamigbo`
1986, 1998, Chude,2005``).
Gully erosion, in contrast to sheet erosion is very obvious because of it disastrous
nature and rapid progress. It is particularly severe in Abia, Imo, Anambra, Enugu, Ondo,
Edo, Ebonyi, Kogi, Adamawa, Delta, Jigawa and Gombe States. In the southeast,
Anambra and Enugu States alone have over 500 active gully complexes, with some
extending over 100 metres long, 20 metres wide and 15 metres deep (UNEP, 2008.)
H. Streambank Erosion: While sheet, rill and gully erosion are active only during or
immediately after rainfall, erosion along the river banks occurs even during and between
rainfall. Impact on surrounding arable soil is remarkable since alluvial soils damaged by
stream bank erosion are usually the more fertile soils (Akamigbo, 1998).
I. Wind Erosion: This is the movement of soil particles by the wind. The particles may
be as fine as sand, which can be moved by drifting at or close to the ground. There is
considerable wind erosion in West African dry tropical Zone where annual rainfall is
below 600mm, the dry season lasts more than six months, and steppe-type vegetation
leaves large stretches of bare soil. It can also develop else where when the soil is being
prepared and large amounts of surface matter are crushed fine. In the areas of Nigeria
which are most affected, wind erosion is most active during the dry season and in the
28
early part of the raining season when the vegetation cover on the landscape is less (Ologe,
1986 and Roose, 1996)
According to Ologe (1986), indicators of wind erosion in the field include;
(i)
Occurrence of dust haze: the dust- laden wind called the harmatan cover the
whole of Nigeria for long and short periods during the dry season. The dust
commonly settles on all exposed objects, including vegetations and ground surface.
(ii) Presence of drifting sand; In areas covered by sands and sandy soils, much
blowing of sand is often seen where the protective cover of vegetation has been
removed. This is common between the harvest and the beginning of the raining
season. The drifting sand may overwhelm, young crops, pile up against obstructions,
such as trees and tufts of grass or obstruct roads.
(iii) Occurrence of deflation hollows: These may be quite small measuring a fraction
of a square metre in area, or they may be several square metres in area. They are
typically surrounded by sharp edges which may still retain their cover of grass
vegetation.
Chude (2005), opined that wind erosions occurs when poorly covered soil is exposed to
winds higher than about 20km/hr. soil loss by wind erosion increases rapidly above the
normal wind level. Fine sand seem to be the most easily moved soil fraction relative to
sand and dry particles. He further stated that the process of wind erosion is as follows; a.
Wind abrasion detaches tiny soil particles. b. Soil particles begin pilling and sliding (soil
creep). c. Tiny particles are carried upward and transported to other places.
29
Ofomata (1988), further classified erosion into two broad subheadings of Actual
erosion and Potential erosion. He stated that the importance of this approach is to
ensure that while we engage in activities aimed at dealing with the existing forms of
erosion, we do not lose sight of the great potentialities of the problem that could empty
any moment under inadequate management strategies. Actual erosion refers to the
different types of erosion on ground while potential erosion is the erosion that occur as
result of the susceptibility of the area to erosion of varying types and degrees.
Actual Erosion:
Fig 3 is the outline map of soil erosion and shows the general state of actual
erosion in south; eastern Nigeria, particularly Enugu state. Two broad types of erosion
are represented on the figure- gully and sheet erosion. The figure also reveals that sheet
erosion is the most widespread type of erosion in the area, the figure also reveals that
erosion in the areas is due mainly to the action of running water. The typology of erosion
outlined above reflects the manner in which this running water, especially its rainwater
run off component, is organized over space. Gully results where running water is
concentrated whereas unconcentrated run off leads to sheet erosion (Ofomata, 1988).
Potential Erosion:
A potential erosion map of the area is embodied in fig 4. The map reveals that all
parts of the area are susceptible to erosion of varying types and degrees. Generally, two
categories of susceptility to erosion could be identified: high susceptibility and moderate
susceptibility. The map is adapted and modified from a preliminary ―map of Nigeria
30
showing erosion susceptibility‖ produced by the Geological survey of Nigeria as GSN
2215 (Ofomata, 1988).
From the map it could be observed that Enugu state is susceptible to various erosion
types and degree (Ofomata 1988).
2.7 Erosion Control
Chude (2005) stated that if one wants to stop water erosion, he or she should have
the following in mind:
a.
Reduce the force of rain impact: That is to protect the soil against direct force of
rain.
b.
Improvement of soil stability: That is to improve the ability of soil structure to
resist deformation/disruption by rain impact.
c.
Reduce the amount of water causing runoff by allowing more water to infiltrate
into the soil.
d.
Reduce the speed (velocity) of flood water,
Erosion control is indispensable in view of the expanding economic activity of
society and the endavour to use natural resources purposefully and economically. The
objective of erosion control is to protect the two valuable natural resources (soil and
water) and to prevent the occurrence of the unfavourable consequence which
deterioration could have for various branches of the national economy which are
agriculture, water management and human environment (Middleton 1990).
31
The method of erosion control measures to be adopted depends on the type of erosion
and there are two type or control; preventive control measures and curative control
measures. The prevention of erosion has always been a much easier, effective and
cheaper task than undertaking curative measures of eroded areas which is more
expensive. Preventive measures involve the use of conservation farming or cultural
practices that minimize raindrop impact, increase or enhance structural stability of the
soil and improve the water intake or infiltration. The curative measures involve
management of surplus water or overland flow for its safe disposal at low velocities
(Abarikwu 1988) , Akamigbo (1998), Ofomata (1982) and lal (1990). According to
Abarikwu (1988), capability classification of the land is an important feature of
conservation farming and conservation practices such as terracing, strip cropping, contour
strip cropping, crop rotation, mulching, minimum tillages, irrigation and drainage are
used depending on the land and the soil.
Erosion can also be controlled either by agronomic measures or soil management
measures or mechanical methods. A range of techniques is available and the decision on
which to adopt depends on whether the objective is to reduce the velocity of runoff,
increase surface water storage capacity or safely dispose of excess water. Mechanical
method are normally employed in conjunction with agronomic measure. Mechanical field
particle are used to control the movement of water over the soil surface. Agronomic
measure for erosion control are those concerned with the utilization of vegetation and
crop to provide cover on the surface to minimise and dissipate erosive forces (Akamigbo
1998, and Middleton 1990) .Akamigbo (1986) opined that erosion control can be carried
out in two broad measures, biological and engineering measures. He stated that biological
32
measures are largely preventive and consequently cheaper. According him, engineering
measures are adopted especially when the erosion problem is already initiated and in
advanced stages and are much more expensive to apply.
Agricultural and forestry measures used for erosion control exist in the correct
location of cultures, a well designed layout of plots and communication system, correct
cultivation of field and forest soils and use of the preventive effective vegetative cover
(Lal, 1982). Use of vegetation for soil conservation involves the use of agricultural and
forest plants. The methods include soil conservation, crop rotation, strip cropping, grass
land farming, protective forest belt, alley cropping agroforestry and afforestation (Senft
1994).
Effects of Agroforestry practices on soil conservation:Agroforestry practices encompass an entire spectrum of land use systems in
which woody perennials are deliberately combined with agricultural crops and or animals
in some spatial or temporal arrangement(Lundgren and Raintree, (1982).The presence of
woody perennials in agroforestry systems may effect several bio-physical and biochemical processes that determine the health of the soil substrate (Nair, 1993). The less
disputed of the effects of trees on soil include amelioration of erosion primarily through
surface litter cover and under story vegetation maintenance or increase of organic matter
and diversity, through continuous degeneration of roots and decomposition of litter,
nitrogen fixation, enhancement of physical properties such as soil structure, porosity, and
moisture
retention due to the extensive roots systems and the canopy cover, and
enhanced efficiency of nutrient use because the tree root system can intercept, absorb and
33
recycle nutrients in the soil that would otherwise be lost through leaching (Subhrendu and
Evan Mercer, 1996 and Sanchez, 1987).
Ojanuga (1986), advises that combating soil erosion in Nigeria requires a
judicious development and management of the land, based on sound scientists principles.
He continued by opining that it calls for judicious land use planning at national, state,
local and more importantly at individual farm level. Morgan (1980),also observed that the
impact of the soil erosion on the environment is not of primary concern to the individual
farmers alone, it is the responsibility of the national or regional authorities advised by
experts dealing with soil conservation.Akamigbo (1986), proposed the adoption of target
erosion control methods. According to him, certain areas are more prone to water erosion
than others. It is not feasible to move towns from their ancestral homes to other
ecological zones. He therefore advocated that such highly susceptible and already
devastated areas of Agulu/Nanka must form target areas for the federal government.
Measure to combat the soil erosion process and thereby save farmlands,
employment and income have for long been implemented by the federal, state and local
governments. The strategies were preventive as well as curative and include the UdiForest consolidation Scheme established in 1922 by the former British colonial office, the
Agulu soil conservation scheme established in 1945 and the Ronasco Anti-Erosion
project executed between 1980-1984 in six designated erosion sites. These and many
other Anti-erosion Schemes were designed and implemented by government officials
without any consultations with the local people (Floyd, 1969).
34
Limited information obtained from scattered sources, however indicate that the
native people of South-eastern Nigeria apply a wide range of traditional techniques to
conserve soil control erosion and prevent soil degradation. These techniques which range
from the agronomic and agroforestry to enthno-engineering (mechanical) aim at two
major results; to prevent as much runoff as possible from reaching the gullies and to
reduce the extent of bare soils susceptible to sheet and rill processes (Ofomata, 1982).
Reference could be made to the popular use of ―mkpuruji‖ (Local mounding) ―ekpe‖
(contour bunds), ―Ogwugwo‖ (pitting systems) and ―Igba‖ (ridging systems) as anti
erosion practices in many parts of the region. These practices are sustained by a
communal works scheme under which household participation is mandatory (Lemchi,
1992).
Eventhough evidence shows that these traditional techniques are curtailing further
gullying, reducing sheet wash and managing run-off, they remain largely understudied,
unexplored and neglected (Reiji, 1990). Despite the fact that these indigenous antierosion techniques provide indisputable starting point for a sustainable environmental
project in the area, local environment knowledge, skills, experiences and expertise cannot
be dismissed as irrelevant in the design and implementation of anti-erosion projects.
Rather, for them to be successful and sustainable, such projects would rely on indigenous
expertise and skill during planning, execution and evaluation (Lemchi 1992). The
environmental researchers and conversationalist have been drawing attention of policy
makers to the approach weakness of the top-down approach to soil conservation
(Reiji.1990, O‘ Riordan, 1990, Showers and Malahcela, 1990).
35
The challenges facing erosion researcher is to articulate, in collaboration with the
local peoples understanding of the technical, agronomic and organisational dimensions of
traditional anti-erosion compain. Therefore, there indigenous systems of anti-erosion
management could be built upon and improved for long term sustenance (Lemchi;
1992).We must strive to protect and enhance the nutrient cycle and to enhance soil
fertility. This means promoting and implementing sustainable technologies and
approaches like alley farming and agroforestry, while eliminating burning and other
wasteful practices. It also means supporting reforestation programs and community tree
planting efforts and letting land rest once every three or four years (Tacio, 2007).
It is our task to conserve the productive capacity of our soils. The wealth and
culture of any country depends upon its topsoil. Once this is gone no agricultural
manipulation will bring it back to full production. Improved methods may increase the
productive capacity of a worn out soil, but the same methods would have resulted in
much larger yields if the soil had not been degraded in the first place. Such soil
restoration becomes necessary in many cases, but our aim should be the conservation and
increase of soil productivity for present and future generations of Nigeria (Ali, 2006).
2.8 Problems and Effects of Soil Erosion.
According to Green (1982), the question of the proper use of agricultural land
touches on the livelihood of every citizen for it is an essential support of human life not
only in relation to food supply, but also for the production of fibre and shelter.
Erosion affect a number of branches of the natural economy and has a far
reaching effect on the social and cultural lives as well as health of the helpless inhabitants
of the affected areas. Agriculture is that branch of the national economy which is most
36
affected by the erosion processes. Millions of hectares of farmland are being affected
these days by soil erosion.
Akamigbo (1998) reported that erosion, as an environment hazard has numerous
adverse effects on the lives and livelihood of people and that it generally results in a
degradation of the environment, and reduction in the land area that is available for
habitation, agriculture, industry, recreation, road construction and other uses. Topsoil
were lost to soil erosion, exposing the gravel layer and the less productive subsoil (Obi
and Asiegbu (1980) and Lal, 1979).Soil erosion is one of the problems menacing
agricultural soil and it results in degradation of soil physical characteristic such as
infiltration rate, soil structure and crusting. It also decreases the efficient use of fertilizers
by increasing the nutrient losses. Woomer and Muchena (1995) opined that soil erosion is
chronic depletion of the soil.Currently the biggest threat to meeting future agricultural
needs comes from soil erosion degradation which according to Douglas (1994) have the
following far- reaching consequence;
* Soil and vegetation: declining soil productivity means less vegetation cover to soil,
less return of organic matter and less biological and nutrient activity.
* Yield: as soil productivity declines, the useful economic yields from crops and pastures
will decline,
* Return to the farmers: declining productivity means that direct returns are reduced,
cost of production increased and sustainability of return is less.
Furthermore erosion also leads to pollution and blocking of water ways, loss and
destruction of social centres and social amenities (Ezeebube, 1989, Akamigbo,1999).
37
FAO (1979) stated that 2.5m of top soil layer was lost in a matter of hours to days in
heavy storm or runoff where the soils were saturated. Soil erosion affects farming in
detrimental ways. Physical damage is the most visible form of soil loss, and most likely
to be remedied (Seafriends,2001).
Akamigbo (1984) reported that appreciable reduction in colloids and clays could
result from vertical erosion with a consequent reduction in fertility. FAO(1965) observed
that losses through water erosion were usually the most fatal, containing the plant
nutrient, humus and the fertilizer that the farmer had applied. Jungerius (1964) reported
that organic matter content was low in the erosion sites of soils of eastern Nigeria
particularly in Enugu state. Tropical soils have a higher concentration of nutrients in the
top soil as compared with temperate soils and this feature was greatest in the highly
weathered soils of intrinsically low fertility (Young, 1989).
Erosion may adversely affect the functioning of the trees themselves in an
agroforesty systems. Habte and Eleswaity (1986) noted in Hawii that stimulated erosion
removal of 7.5 to 37.5cm topsoil greatly reduced nodulation, nitrogenase activity,
nutrient uptake and growth of Sesbania gradifora. Dike (1995), opined that erosion
reduces yield and productivity of crop and soil through the various ways; loss of plant
avaiblewater, loss of plant nutrient, degradation of soil structure, non-uniform removal of
soil within a field and affecting timing of farming operations. Apart from the effects of
erosion on agriculture, rivers are filling rapidly with sediments of soil particles which
threatens both domestic and irrigation water supply (Cooke,,Doorkamp,Brunsden, and
Jones,(1995) and Mumel,(1995).
38
The transportation of soil particles by wind erosion had adverse effects on whole
areas. Debris and soil removed by wind erosion are often deposited on vegetation and
they damage buildings, communication, canals, and ditches (Middleton, 1986). Skidmore
(1986) stated that blowing soil fills roads and ditches, reduces seedling survival and
growth, lowers the marketability of vegetable crops like asparagus, green beans, lettuce,
and okra, increases the susceptibility of plants to diseases and contributes to transmission
of some plant pathogens. Leather, (1981) reported that soil particles carried by wind
pollute the atmosphere causing health hazards to people and animals who suffer from
disease of the respiratory track and eye inflammation.Pye (1987) proved that about 310
tons of dust particles are in 1km3 of air in a dust storm and dust pollution obscures
visibility and causes antomobile and aircraft accidents.
Another grave danger of erosion to the society is the transportation of chemical
substances which infiltrates surface and underground water and limits the use of water
resource (Goudie, 1983). The fragment sources of these chemicals are chemical
fertilizers, and the different pesticides, herbicides and fungicides applied in large
quantities in agriculture as well as industrial and agricultural wastes discharged on or into
the soil. Also large scale atmospheric dust concentrations affects local meteorological
processes and may over long period lead to reduced rainfall (Middleton, 1989).
Deposition of chemicals on the sea, river, streams, oceans affects biological
balance in streams, rivers and other bodies of water leading to eutrophication (excess
nutrient) phenomenon in streams, rivers and lakes (Svatos,1975). Mellanby (1967),
noticed that polluted water especially by pesticides is a health hazard to man not only
directly through contact but also through food chain. Other problems of erosion as
39
reported by Odoh (1995) and Akamigbo (1999) are destruction of roads, lives, houses,
flooding and starvation As far back as 1964, 47% of the soil of Eastern Nigeria was
affected by measurable sheet erosion while 20% suffered from severe sheet erosion
(Ofomata 1976). By 1990, gullies occupied 4% of the land area of Anambra, Imo, Abia
and Enugu states and the rate of gully formation and the extension of existing ones was
still increasing (World Bank, 1990).Soil erosion causes a reduction in available farm
lands (Chude, 2005).
The world loses the equivalent of five to seven million hectares of farmland
through erosion each year. This is equivalent to the land area of Belguim and the
Netherlands combined. Soil experts says there is nothing wrong with normal soil erosion,
which in even beneficial to man, but accelerated erosion usually caused by man himself
is harmful. Studies have shown that as much as 20 percent of eroded materials end up in
rivers, reservoir, and irrigation canal and siltation also cause serious damage to coral
reefs and coastal fisheries (Tacio, 2007). Soil erosion is main agricultural externality and
a main threat for sustainability in agricultural systems, as it reduces the potential for
agricultural production. The loss of topsoil affects main‘s ability to grow food in two
ways. First, it reduces the inherent productivity of land, both through nutrient loss and
degradation of the soil‘s physical structure, second, it increases the cost of food
production to maintain the level of agricultural production in the farm (Franco and
Calatrava-leyva (2006) and Tacio, (2007). Tacio (2007), and Akamigbo (1999)
concluded that if productivity drops tow low or cost rise too high farmers will be forced
to abandon their land. In both cases, soil erosion result in a land rent loss and in
40
productive capital loss that may result in a decline in the market value of eroded land
(Franco and calatrvaa-leyra (2006) and Akamigbo, 1999).
Erosion has social and psychological impact on people‘s lives. This impact is
incalculable (Onwueme and Asiabaka, 1992). Many villagers in gully- prone area live in
constant fear of their lives and properties, not knowing whether the buildings which they
occupy today will end up in the bottom of a gully the following day. There is high degree
of personal and communal insecurity. It results in social up heaval. Erosion also induces
superstition since some people claim that gully erosion is a retribution from the gods.
Quarrels and fighting often arise as the available uneroded land is fragmented to unviable
agricultural tracts for an agricultural community (Akamigbo, 1999).
Gully erosion has had and will continue to have destructive impacts in and around
southeast of Nigeria in the absence of immediate corrective and preventive measures
(Orabuchi, 2006).
2.9 Documentation of Farmland Erosion Sites in Enugu State.
Devastating erosion sites cut across the state . some of them are listed below.
EROSION SITES IN ENUGU STATE
1, Ajali Owa water Works
- Major
2, 9th Mile by Ama on Road Leading to Eke in Ezeagu
-Major
3, Agbani (Eke Market) Erosion Site
4, Akugo Ndiagu to Obuno Akpugo Erosion Site
-Major
5, Ezimo Uno Erosion Site
–Major
6, Obiekpo-Abor Erosion Site
-Major
7, Umualor Mamu Forest Ugwuoba Erosion Site
41
8, Ugwu Egbe Obollo-Afor Gully Erosion Site
Leading to Federal College of Education, Eha-Amufu
-Major
9, Ugwugo- Opi Road Gully Erosion
10 Ebe Erosion Site
11, Ozalla Nkanu Erosion Site
12, Obinagu Gully Erosion Site
13 Eke Ogbaku Erosion Site
14 Ugbawka Erosion Site
15 Akegbe Ugwu Erosion Site
16 Agungwu Ugwuoba Gully Erosion Site
-Major
17, Access Road to Ajali Water Workes/ Ajali Erosion Site
-Major
18, Timber Shed Erosion Site
19 Agulu- Amokwe Road Erosion Site
20,Ukehe-Agukehe- Agu Umunko Erosion Site
21, Enugu-Port Harcourt Express Road Erosion Site (by Nyaba Bridge)
22, Umuokoloma-Affa
-Major
23, Okwojo Ngwo/Agbaja Ngwo Erosion Site
24 Ogugu- Awgu Erosion Site
25 SEDES SPIENTIAE Oghe
26 Community Secondary School Amokwe
27 Airport-End of Run Way 26 by Niger Gas Emene Enugu
28 Obeleagu Umana Erosion Site.
–Major
29 Coca Cola 9th Mile Corner Erosion Site
- Major
30 Obimo Erosion Site
-Major
42
31 Ugwuoba-Nidukwuenu Awa
-Major
32 Eke Oghe
-Major
33. Onyeama Mine (Erosion-Onitsha Expressway)
-Major
34 Egede Amozalla-Affa Road Erosion Site
-Major
35 Lejja Nsukka Erosion Site
-Major
36 Amokwu Affa Erkosion Site
Major
Source: Enugu State Ministry of Environment, (2008).
2.10 Review of Existing Farm Management Erosion Control Practices.
1. Crop Rotation: This is the method of farming in which the same piece
of land is kept under cultivation every year in such a way that the crops follow a definite
order planned in such a way as to restore nutrients removed from the soil. The different
canopy formation and rooting patterns will prevent undue soil exposure thereby helping a
great deal in erosion control. A crop rotation that includes forages can reduce soil loss by
water erosion and, slow the buildup of insects and disease problems encountered with a
continuous cropping program (Stone, 1996). Akamigbo, (1998), opined that suitable crop
for use in rotations are legumes and grasses which provides good ground cover, help
maintain or even improve the organic status of the soil, thereby contributing to soil
fertility, and enable a more aggregate structure to develop in the soil.
2. Cover Cropping: Cover cropping is an agricultural practice in which crops with good
canopy formation are planted with other crops so that their canopy formation can shield
the soil from the effect of soil erosion causing agents. Cover crops control erosion by
intercepting the raindrop and absorbing their kinetic energy(Akamigbo,1998). Morgan
43
and Rickson (1995), opined that the cover reduces the energy of the rainfall at the soil
surface which in turn reduces the rate of soil particle detachment by raindrop impact. A
good cover cropping species should have easy establishment, vigorous growth under
local condition, ability to cover weeds quickly, ability to either fix plenty nitrogen or
concentrate plenty phosphorus. Some food crops which can serve as excellent cover
crops are melon, groundnut, cowpea etc (Chude,2005).
The choice of an appropriate cover crops differs among soils, rainfall regimes and
agroecological environment. Suitable leguminous and grass cover crops include;
Pueraria phaseoloides, Calopogonium mucunioides, Centrosema pubescens, Panicum
maximum and Penmisetum purperum, (Akamigbo, 1998).
3. Strip cropping: This is the practice of growing alternate strips of different species of
crops on the same field. Planned strip cropping techniques provide protection from
erosion both by rain and surface flow (Uguru, 1981). It is also a conservation practice in
which crops are grown in a systematized arrangement of strips or bands that serve as
barriers to wind and water erosion. Surface run off moving down the slop is intercepted
by the strips, the velocity is slowed and silt deposited in the grass strip. This technique is
effective when the erosion is not severe (Akamigbo, 1998 and Chude, 2005).
4. Mulching: Mulching is the covering of the soil with crop residues such as straw,
maize stalks, palm fround or standing stubble. Mulches are used to protect soil surfaces
from erosion agents of rainfall, runoff and wind. They also help to reduce intense solar
radiation, suppress extreme fluctuations of soil temperatures reduces water loss through
evaporation and increase soil moisture which can assist in creating ideal conditions for
plant growth in many circumstance. Other gains of mulches include, suppression of
weeds thereby saving weeding costs, increase in soil organic matter, increasing
44
infiltration rate and maintaining the exchange capacity at a level where nutrient leaching
losses are minimized and hydrogen saturation is kept within bounds (Sprague and –
Tripleft 1986, Akamigbo, 1998, Morgan and Rickson 1995 and Chude 2005). The
benefits of mulching are proportional to the adversity of the environment in which they
are applied (Jackobs,Andrews,Murdoch and Foote, 1967).
5. Terracing: Terraces are earth embankment constructed across the slope to intercept
surface runoff and convey it to a suitable outlet at a non erosive velocity and to shorten
slope length. They thus perform similar functions to contour bunds. Terraces can be
classified into three main types; diversion, retention and bench(Akamigbo (1998) and
Chude (2005). Terraces reduces slope length and prevent deposition of sediment
(Czapar,Laflen,McIIsaac and Mckenna,2006).
6. Fertilization: This is the application of organic fertilizers or organic manures such as
green manures, farmyard manures, animal dropping etc. These manures serve as cover
and improve soil fertility and increase the resistance of the soil to erosion (ie, they
improve aggregate stability of the soil (Akamigbo 1998 and Chude 2005).
7. Conservation Tillage: This is any tillage or planting system in which at least 30% of
the soil surface is covered by plant residue after planting to reduce erosion by water. By
this definition no-tillage, minimum tillage, reduced tillage and much tillage are all terms
synonymous with conservation tillage. The benefit of tillage includes, preventing loose
soil materials from forming a crust or being carried away by water, perventing runoff in
erosion sensitive surfaces and promoting easy entrance of water into the soil as well as
penetration of plant roots (Akamigbo Ibid and Chude Ibid and Stone ,1996).
45
8. Afforestation: Afforestation involves planting of trees to help conserve the forest. It
controls soil erosion by slowing down run-off through rooting activities and in
intercepting raindrop thereby preventing both sheet and raindrop erosion.
9. Tied-Ridging: On silty and fine sandy soils, erosion may be further reduced by storing
water on the surface rather than allowing it to runoff. Limited increase in storage capacity
can be obtained by forming ridges. Greater storage is achieved by connecting the ridges
with cross-ties over the intervening furrow thereby forming a series of rectangular
depressions which fill with water during rain. As crop damage can occur if the water
cannot soak into the soil within 48 hours, this practice should only be used on well
drained soils. If it is applied to clay soils, water logging is likely to occur (Akamigbo,
1998).
10. Water ways: The purpose of waterways in a conservation system is to convey runoff
at a non-erosive velocity to a suitable disposal point. A waterway must therefore be
carefully designed. Water ways can be of three types, diversion channels, terrace
channels and grass waterways (Akamigbo Ibid).
11. Mixed cropping: According to Lal (1987), the subsistence farmer who risks famine
would consider a successful technology to be the one that produces some yield in the
worst year rather than one that produces a high yield in the best year. Mixed cropping
ensure that the soil is usually protected by a vegetative cover. Under such systems,
erosion hazard is less than in modem row crop production or in monocropping
(Akamigbo Ibid).
12. Contour Bunds: It entials a very big ridge built with earth for the purpose of erosion
control and the maintenance of soil control fertility. It is normally built on the contour to
delay moving water and allow soil to remain in place.
46
13. Weeding: Weeding is one of the essential cultural practices in farming. By
controlling the population of weeds in the farm, reduction in evapo-transpiration is
achieved. After weeding, the physical properties of the soil are improved with the result
that infiltration is enhanced which implies less erosion.
Fig. 1: Technology options for erosion management on newly cleared land
Erosion management
Control
measure
Preventive
measure
Soil & crop
management
Soil
management
.Conservation tillage
barries
. Mulch farming
. Contour farming
Source-Lal(1995)
Runoff & slope
management
Crop
management
. Cover crops &
Slope
management
. Diversion channels
planted fallows
. Graded channel
. Vegetative hedges terraces
& barriers
. Engineering
. Strip cropping
Structures
. Multiple cropping
. Improved crop
Management
practices
Runoff
management
. Vegetative
. Water reservoirs
. Check dams
47
2.11 Theoretical Framework
Biological and ecological processes create connections between the rates of
resources use in the present and the quantity and quality of resources available for future
generations. It is these connections that are the focus of what has come to be called
sustainability. A resources use rate that is ―sustainable‖ is one that can be maintained
over the long run without impairing the fundamental ability of the natural resources base
to support future generations. Sustainability does not mean that resources must remain
untouched, rather, it means that their rates of use be chosen so as not to jeopardize future
generations (Field, 1997).
In the absence of rational and conscious sustainable exploitation of the physical
and natural resources, irreplaceable or probably irreversible damages inevitably result.
(Titilola,1998). According to Ress (1989,3) sustainable development is positive
socioeconomic change that does not undermine that ecological and social systems upon
which communities and social systems are dependent.
In relation to agriculture, sustainability means changing agricultural systems so
that farmers are able to produce indefinitely (Rodale, 1988). Hence, sustainable
agriculture should be based on approaches that reduce environmental degradation,
conserve resources, and provide an adequate and dependable farm income through
reducing poverty and associated problems.
The theory of sustainable use of natural resources is based on the theory of natural
resources scarcity and its effect on growth and partly on the principles of natural
resources conservation (Titilola, 1998). The theory, which is credited to some classical
economists like Malthus (1798), Ricardo (1821) and Mills (1963) holds the view that
scarcity of natural resources would eventually lead to diminishing social and economic
48
returns to human efforts and ultimately to stagnation, retardation and cessation of socioeconomic growth. Natural resource such as soil, water, and vegetation, Livestock, and
minerals are specific in type, location, quality and relationships to one another.
There are several agricultural resources but in this case, implication of resources
management for food production and food security are illustrated by focusing on the
issue of land availability and usage. Land is perhaps the most important producing input.
Ownership affects land use, farming systems, institutional structures, ecological
conditions, adoption and usage of technology, food production and self sufficiency, and
overall wellbeing of the rural and urban population. Poverty and resource misuse is
linked because of the pattern of land distribution, which often favours the rich class. The
rich have access to land, which is less prone to degradation or erosion. In addition, the
rich class has the economic resource to invest in and improve the land. However, poor
farmers continue to till a marginal resource base despite increase in their number (Titilola
1998).
Land resource management is the actual practice of the users of the land by the
local human population, which should be sustainable (FAO/Nethelands, 1991). In a
boarder sense it included land-use planning, as agreed between stakeholders; legal,
administrative and institutional execution, demarcation on the ground, inspection and
control of adherence to decisions, solving of land tenure issues, settling of water rights,
issuing of concession. For plant and animal extraction (timber, fuelwood, charcoal and
peat, non-wood products, hunting), promotion of the role of women and other
disadvantaged groups in agriculture and rural development in the area; and the
safeguarding of traditional rights of indigenous peoples are essentials (FAO, 1995).
49
Yudelman (1987) noted that the accelerating deterioration of the resource base in much
of sub-Saharan Africa threatens to reduce production.
Soil erosion is aggravated by such factors as the farming system, soil management
practices and poverty. The impact of resource management, especially by erosion
management on the farm size, farm output and value of output are deemed serious for the
Nigeria agricultural societies. Erosion has (a) reduced the areas farmed to about one third
of the original size (b) reduced physical output to about two third and (c) reduced the
monetary value as well. The implication of this study for agricultural resources
management in Nigeria is that farmers and other rural resource users are most important
factors in the prevention and management of erosion. These resource users dominate the
agricultural resource in terms of number of producers and proportion of output produced
given the economic situation, under which they operate. They place more emphasis on
short time planning, essentially minimizing risk and minimizing income. They can
therefore be motivated in soil livelihood. The measures that will adequately encourage
resource management must satisfy the following conditions; (a) it must be profitable in
the short run (b) it must include some aspects of existing farming system practices and (c)
it must not require farmers to donate their most limiting resources (Titilola, 1998).
In order to avoid the depletion of natural resources thus reducing the growth and
development propensity of nations, the need to use the most efficient production and
extraction system is essential. The conservation of natural resources, however, entails a
better knowledge of the limitations imposed by the natural and man- made misuse of the
environment as well as the need for ecological balance (Titilola, 1998). One area where
misuse of the environment is obvious is in the reduction of the quality of the land
50
resources. A shortened fallow period leads to both overgrazing and over cropping
resulting in erosion degradation and impaired quality (Courier, 1984).
Improved land management that ensures better resource use and promotes longterm sustainability is basic to future food production and to the economic welfare or rural
communities (USDA, 1994).
From an economic point of view the existence and persistence of soil erosion in
croplands is due to several market failure. The most important are the off-site water
pollution caused by erosion, the lack of information regarding the economic value of soil,
and the failure to in corporate long-time soil use (Weda and Heady, 1978, and Mc
Connell ,1983).
Regarding the social dimension of the problem, it is evident that there are clear
social benefits from soil conservation, which reduces externalities and off side damages
(such as reduction of sediment in rivers, chemical damage to fish etc). These social
benefits may warrant conservation even when private profitability is absent (Walker,
1982; 1982; Araya and Asafu-Adjaye ,1999). The main focus of studies about this issue
has been the analysis of the inter-temporal path of soil use and the conditions under
which private and social optima diverge (Calatrava-cayva et al 2005). Some authors
beginning with Mcconnell (1983), also gave insight about effective instruments of
erosion control. For Mcconnell (1983), if farmers were aware of the impact of soil depth
on those they would conserve it. What lays below this affirmation is that, in absence of a
market for soil depth, the market for agricultural land will play such role (Araya and
Asafu-Adjaye 1999). The impact of erosion control has been frequently studied using
hedonic land valuation techniques, despite the kind Examples are the papers by
miranowski and Hammes (1984), Gardner and Barrows (1989), Ervin and Mill (1985),
51
King and Sinden (1988) and Palmquist and Danielson (1989). The aim of these studies is
to provide information to farmers about the value given to land in the market to erosion
control, what would help investment decisions, as well as policy-markers that design
policies aiming to achieve certain standards of erosion (Palmquist and Danielson, 1989).
The influence of the level of soil erosion on the value of agricultural land depend on the
area where it is studied (Miranowski and Hammes, 1984; Hertzler,Ibanez-Meier,and
Jolly, 1985). However in some cases it may even be not relevant at all (Gardner and
Barrows, 1985; Ervin and Mill, 1985)
The process of intensification in agricultural production has increased soil erosion
in agricultural systems up to a point in which it is a main agricultural externality and a
main threat for agricultural sustainability as it reduces the potential for agricultural
production. Soil erosion has a multiple dimensions (biological physical, economic,
ecological, social etc) that should be considered together in order to make advance in
solutions. The socio-economic side of the problem has often been neglected in most
technical studies. The economic analysis of soil erosion have mainly focused in two main
aspects of the problem, namely the decline of soil fertility and the resulting loss in
agricultural productivity and the pollution effect of sediment load in water courses
(calatrava-leyval,Franco and Gonzalenz-Roa, 2005). They finally opined that soil erosion
results in increased production cost, land rent loss and in a productive capital loss that
may result in a decline in the market value of eroded land.
Farmer perception of the problem of soil erosion, its costs and benefit is key to
determine the usage of soil erosion control practices. The literature shows that farmers
are aware of the problem, although there are many factors that cause farmers not to care
about soil loss in that they can substitute other inputs for soil depth (Wade and Heady,
52
1978). This causes the failure to incorporate long term use benefits in their utility
function (Lee, 1980).
Farmers responses to soil erosion will depend of many diverging factors both
technical (cropping patterns, slopes, type of soil, etc) and socio-economic (farmers age,
skills, wealth, etc). One option is to do nothing maintain the same technology, practices
and level of input use, what leads to a continued soil loss and a decline in agricultural
production. A second option is to intensify production substituting other inputs (such as
fertilizers) for topsoil depth, what generally worsen soil loss and increase production
costs. A third option is to adopt new practices to conserve soil, what may have a negative
economic effect on the short run but positive one in the long run, although ambiguous
evidence exists in this sense. Last, he may regenerated topsoil, incurring even larger costs
(Franco and calatrava-layva, 2006).
An important group of factors effecting adoption of soil conservation practices
relate to soil characteristics and the time frame of adoption. Most studies show that in
deeper soils the incentive to conserve appears more on the long run, as top soil is lost and
the yield function exhibits diminishing marginal returns to topsoil depth. Incentives are
far more appealing for steeper slopes and more eroded lands (Walker, 1982). A second
main factor is the investment costs of adopting control practices, that are generally lower
in areas with smaller risk of soil erosion are more less steeped slopes, where benefits
usually surpass costs. Investment costs are also affected by aspects such as the loan
repayment conditions, interest rates etc. Another important factor is the relationship
between potential erosion and land productivity, and to which extent conservation
practices affect agricultural production and farm profits, are more likely to be adopted.
53
This probability increases the more these practices reduce erosion (Franco and calatravaleyval, Ibid)..
Other factors commonly found in the literature to be related with the adoption of
soil erosion control practices are the level of non-farming income, labour and or
machinery availability, land tenancy issues (property incentives adoption and
investment), the level of risk aversion, continuity of sons/relatives in framing, and the
existence of public programmes. Last, lower income farmers are usually more concerned
with short term survival than with the long term benefits of soil conservation.
The socioeconomic factors affecting the use of a particular farmland erosion
control practices as a concept of resource use sustainability can best be captured using
multinomial logit model. The multinomial logit regression is used when the dependent
variable in question which is the erosion control practice is nominal and consist of more
than two categories.
Erosion control practice is an alternative decision facing a farmer in order to
ensure sustainability of resource use for increased productivity, food security and
environmental quality.
The costs and benefits of such an alternative of erosion control practices can be
measured using partial budget analysis as it is a veritable tool used to calculate the
expected change in profit for a proposed change in the farm business. The extent of
causes of erosion on the farmland can be assessed using a 3-point Likert scale rating. The
Duncan‘s Multiple range test is a comparison test tool that can capture the significant
difference in the means of net-benefits of different erosion control practices.The details
are found in the analytical framework below.
54
However, erosion control practices especially in Enugu State is one of the concept
of sustainable use of natural resources for food security and environmental sustainability.
2.12 Analytical Framework
Eboh (1998), reported that the frameworks of analysis adopted for any research
study depends on the available information and the purpose of research. He also stated
that while means, frequencies, rates and percentages may be adequate for some
exploratory studies, more detailed and higher level analysis will be required for case
studies and sample surveys especially those that deal with quantitative data.
2.12.1 Multinomial Logit Model.
In statistics, economics and genetics, a multinomial logit model is a regression
model which generalizes logistic regression by allowing more than two discrete outcomes
(Wikipedia, 2008). Multinomial logit regression is used when the dependent variable in
question is nominal (a set of categories which cannot be ordered in any meaningful way)
and consists of more than two categories. It belongs to the disaggregate choice models of
consumer research. The models is also appropriate in cases where the parallel regression
assumption of ordered logit regression is violated. Ordered logit regression is used in
cases where the dependent variable in question consists of a set of number (more than
two) of categories which can be ordered in a meaningful way (for example, highest
degree, social class) (Wikipedia, 2008c and Bartels, Boztup and Muller,(1999).
Assumptions.
The Multinomial logit model assumes that data are case specific; that is, each
independent variable has a single value for each case. The multinomial logit model also
assumes that the dependent variable can not be perfectly predicted from the independent
55
variables for any case. Collinearity is assumed to be relatively low, as it becomes difficult
to differentiate between the impact of several variable if they are highly correlated. The
independence of irrelevant alternatives (11A) is another assumption which the
multinomial logit model makes. This assumption states that the odds do not depend on
other alternatives that are available (ie. That including additional alternative or deleting
alternatives will not affect the odds on the dependent variable among the alternatives that
were included originally) (Wikipedia, 2008).
Biercaire (1997), also saw this independence from irrelevant Alternatives (11A) as an
important property of the multinomial logit model which states that; the ratio of the
probabilities of any two alternatives is independent from the choice set. That is, for any
choice sets S and T such that S  T  C, for any alternative α1 and α2 in S we have
PS (α1)
=
PS (α2)
PT (α1)
PT(α2)
If the error terms are independent and identically Gumbel distributed, with location
parameter Ο and scale parameter μ, the probability that a given individual choose
alternative ί within C is given by
PC(‫ =)ﺂ‬eμν ‫_____ﺄ‬
∑KECeμvk
Ben-Akiva and Lerman (1985) proposed an equivalent definition of 11A: The ratio of
choice probability of any two alternatives is entirely unaffected by the systematic utilities
of any other alternatives.
56
Usage:
When using multinomial logistic regression, one category of the dependent variable is
chosen as the comparison category. Separate relative risk ratio are determined for all
independent variable for each category of the independent variable with the exception of
the comparison category of the dependent variable, which is omitted from the analysis.
Relative risk ratios, the exponential beta coefficient, represent the change in the odds of
being in the dependent variable category versus the comparison category associated with
a one unit change on the independent variable (Wikipedia, 2008c).
The model:
Exp (Xί β‫)ذ‬
Pr (yί=j)= 1+Σ‫ﺯ‬J exp (X ‫ﺄ‬βj)
And
1
Pr (y¿=O)= 1+Σ‫ﺯ‬J exp (Xί β‫‘)ﺯ‬
Where for the ίth individual yί is the observed of outcome and Xί is a vector of
explanatory variables. The unknown parameters β ‫ ﺯ‬are typically estimated by maximum
likelihood.
The multinomial logic model has been used by Nkamleu (2007) in modelling
farmers‘ decisions or integrated soil nutrient management in sub-Saharan Africa, by
Enete (2003) to study resource use, marketing and Diversification Decision in Cassava
Producing Household of sub-Saharan Africa, by Onyekuru (2007) to study the impact of
57
changes in cooking energy prices on product substitution and resource allocation a
comparative analysis of rural and Urban households in Enugu State, Nigeria and
Bartels,Boztup and Muller,(1999) to describe purchases of one type of health care
products over 104 weeks in a scanner panel data set.
As Multinomial logit model is a model that allows more than two discrete
outcomes, I deemed it necessary to use the tool to determine the socioeconomic factors
affecting the use of specific farmland erosion control practices in my study area.
2.12.2 Partial Budgeting
Partial budgeting is a planning and decision-making framework used to compare
the costs and benefits of alternatives faced by a farm business. It focuses only on the
changes that would result from implementing a specific alternative. Thus, all aspects of
farm profits that are unchanged by the decision can be safely ignored. In a nutshell,
partial budgeting allows you to get a better handle on how a decision will affect the
profitability of the enterprise and ultimately the profitability of the farm itself (Hyde and
Roth (2002)
When and how to use partial Budget;
The partial budget framework can be used to analyse a number of important farm
decisions, including;

adopting a new technology

changing enterprises

choosing to specialize

hiring custom work
58

leasing instead of buying machinery

modifying production practices

making capital improvements
The structure of the analysis depend upon the nature of the decision being analysed (Roth
and Hyde 2002).
Sections in a partial budget.
The partial budget compares the positive and negative effects of the proposed change on
net income. You then separate the positive and negative effects and list then in different
sections of the partial budget.
Income change
Reduced
income
Additional
income
Additional costs
Reduced
costs
Present income
Fig. 2: An illustration of the partial budget.
The partial budget is illustrated above as a balance which measures the positive
and negative effects of a change in the business. The left side of the balance shows the
positive effects on net income including additional income and reduced cost. To
59
counterbalance this .positive effect, the right side of the balance includes reduced income
and additional cost or the. Negative effects of the proposed change. Therefore the partial
budget has four categorical parts: additional income, reduced costs, reduced income and
additional costs (Lesley,Johnson,and Hanson,(1991). Summarize the net income or
effects.
Once you have identified the individual positive (steps1 and 2) and negative (steps 3 and
4) aspects of the alternative, these should be aggregated to determine a total cost and
total benefit of the alternative. The net benefit of the alternative is fund by subtracting
total costs from total benefits. IF the net benefit is positive, then that alternative may be
have some economic advantages However, if the net benefit is negative, the business
wild be better put off staying with the current situation or analysing a different alternative
(Roth and Hyde 2002).
Partial budgeting has been used by lessley,Johnson,and Hanson,(1991) to analyse
substituting one enterprise for another and custom Hiring or owning a combine, Roth and
Hyde (2002) in analysing the net benefit of raising heifer and Utazi
(2002) in an
Economic study of farmland erosion control practices in imo state.
I therefore found it worthy to use the partial budget analysis to determine the net
benefit of farmland erosion control practices in Enugu state, Nigeria which is the third
objective of my study. Reason being that partial budgeting is an analytical tool that
compares the costs and benefits of alternatives facing a farmer.
60
2.12.3 Duncan’s Multiple-Range Test
In statistics, Duncan‘s new multiple range test (MRT) is a multiple comparison
procedure developed by David B. Dauncan in 1955. Duncan‘s MRT belongs to the
general class of multiple comparison procedures that use the studentized range statistic q r
to compare sets of means (Wikipedia, 2008a).
This procedure is based on the comparison of a range of sample means in the
subset. If the range of the subset exceeds the least significant range, then the population
means can be considered as significantly different. It is a sequential test and so the
subject with the largest range is compared first, followed by smaller subset. Once a range
is found not to be significant, no further subsets of this group are tested. The least
significant range, Rp for subsets P sample means is given by:
Rp = rp
S2
n
Where rp is called the least significant studentized range and depends upon the error
degrees of freedom and the numbers of means of the subset. Tables of these values can be
found in many statistics books, S2 is the error mean square from the analysis of variance
table, and n is the sample size for each treatment (Bewick,Cheek,and Ball, 2004).
David B. Duncan developed this test as a modification of the student-NewmanKeuls method that would have greater power. Duncan‘s MRT is especially protected
against type ll error at the expense of having a greater risk of making type I errors.
Duncan‘s test is commonly used in agronomy and other agricultural research (Wikipedia,
2008).
61
CHAPTER THREE
3.0 METHODOLOGY
3.1 The Study Area
Enugu state which was the study area falls within the rainforest zone vegetation
and is located between latitudes 50561N and 70.051N and longitudes 6 0531E and 70551E
(Anyadike, 2002 and Wikipedia, 2008). Enugu state is one of the states affected with
erosion epidemic in Nigeria (Akamigbo and Ofomata, 1988). The state has a landmass of
approximately 1069km2 with a population of 3,257,298 (Male: 1,624,202, and female:
1,633,096) (Ajero 2006, and NPC, 2006).
Enugu state is made up of seventeen local government area and shares boundary
in the north with Benue and kogi state, south with Abia state, east with Ebonyi state and
west with Anambra state. The state is also divided into three agricultural Zones as shown
in the soil map. The zones include;
* North Agricultural zone-comprising Udenu, Igbo-Etiti, Nsukka, Igboeze south, Igboeze
North and Uzo-Uwani.
* East Agricultural zone-consisting of Isi-Uzo, Enugu-East and Enugu North, Enugu
South, Nkanu East and Nkanu west.
* West Agricultural zone-comprising Udi, Awgu, Ezeagu, Oji River and Aninri
(ENADEP, 2008 and ENMOI, 2005).
The predominant soil type in Enugu state as shown in the soil map is sandy
followed closely by gravel, loamy and a small amount of clay soil. This predominant
62
sandy soil makes the area susceptible to sheet erosion which poses a major threat to
farmland.
3.2 Sampling Procedure.
The study made use of both purposive and random sampling techniques for
selection of the respondents. The first stage involved a purposive sampling of six (6) out
of the seventeen (17) local government areas, two (2) from each of the three agricultural
zones of the state. The sampling of the six local government areas was guided by the high
number of farmland erosion sites present in the area as well as the soil type map of Enugu
state such that two local government areas with the most predominantly sandy soil
structure were selected in each agric zone.
Stage two involved a random sampling of four communities from each
agricultural zone, two communities from each selected local government. This gave a
total of twelve communities.
Stage three involved a random sampling of fourteen crop farmers from each of the
twelve (12) sampled communities. Therefore in all, one hundred and sixty eight farmers
(168) were selected and interviewed. The list of farmers in each community was obtained
through the assistance of the community‘s extension officer. The L.G.As selected were;
Udenu and Igboetiti for Enugu-north agricultural zone, Udi and Ezeagu for Enugu-West
zone and Enugu-East and Nkanu-West for Enugu-East zone. The communities selected
were Ezimo and Obolo-Orie for Udenu,Umunna and Ukeghe for Igboetiti LGA,Umuoka
and Ebe for Udi LGA, Oghe and Obinofia Ndiagu for Ezeagu LGA, Agbani and Ozala in
Nkanu West Local Government Area and Ibagwa and Ugwogo in Enugu-East Local
Government Area.
63
3.3 Data Collection
A cross-sectional data was used for the study. The data was obtained by using a
combination of structured questionnaire, on farm observation and measurements. The
questionnaire elicited information on farmers farm resources, their usage of erosion
control, type of treatment, erosion affected field size,and agronomic characteristics.
Others include direct capital our lay in constructing and maintaining erosion control
structures, labour and material charges, production cost charges, yield and income.
3.4 Data Analysis
The data generated were analyzed using the following analytical tools.
Objective (i) and (iv) was realized using descriptive statistics such as mean; percentages
frequencies and Ranking and Likert scale rating
Objective (ii) was realized using Partial budget analysis and Profitability index.
Objective (iii) was achieved using Multinomial logit model.
3.5 Test of Hypotheses
Hypotheses (i) was tested using Multinomial logit model at 0.05 level of significance.
Hypotheses (ii) was tested using Duncan‘s multiple range test at 0.05 level of
significance.
64
3.6 Model Specification
3.6.1 Multinomial Logit Model
According to Akamigbo, 1998, Chude, 2005, Lal, 1995, Morgan and Rickson, 1995 and
Stone, 1996 and ENADEP,2007, there are about five soil erosion control practices. Hence
the multinomial logit model to realise this objective (III)
Four steps are distinguished in the household farmland erosion control practice
choice. A step is assigned one if a farmer uses Multiple cropping, assigned two if the
farmer uses Construction of bonds , assigned three if the farmer uses Ridging across
the slope assigned four if Cover cropping. With these four possible options, steps
1,2,3,and 4 defined for the different erosion control practices, Multinomial logit model
was used for the analysis.
According to Enete (2003) a set of coefficient  (1) ,  (2) ,  (3) ,  (4), corresponding to
each outcome can be estimated as:
Pr (z=1) =
exβ(1)______________________
...........................(1)
eβ(1)+ exβ(2) + exβ(3) + exβ(4)
Pr (Z=2)= ___ exβ(2)_________________
………………….(2)
exβ(1) + exβ(2)+ exβ(3)+exβ(4)
Pr (Z=3) = ____exβ(3)___________________
………………….(3)
exB(1) + exB(2) +exB(3) + exB(4)
Pr (Z=4)= ____exβ(4)____________________
..............................(4)
exβ(1)+exβ(2)+exβ(3)+exβ(4)
The model however is unidentified in the sense that there is more than one solution to
β,(1)β,(2)β,(3)β, (4), that leads to the same probabities for z=1, Z=2, Z=3, Z=4. To
65
identity the model, one of β(1),β(2), β(3),β(4), is arbitrarily set to 0. That is if we arbitrarily set
β(2), = 0 the remaining coefficients β(1),β(2),β(3),β,(4) would measure the change relative to
the Z=2 group. Setting β(2), = 0 the above equation become.
Pr (Z=1) =
___exβ(1)________________
………………………(6)
exβ(1)+exB(2)+exβ(3) +1
Pr (Z=2) = _____1________________
……………………...(7)
exβ(1) + exβ(2)+ exβ(3)+1
Pr (Z=3)= _______exB(3)______________
……………………..(8)
exβ(1)+exβ(2)+exβ(3) +1
Pr (Z=4) = ______ exB(4)_______________
……………………... (9)
exβ(1) + exβ(2)+exβ(3)+1
The relative probability of Z = 1 to the base category is
Pr(Z=1)
=exβ(1)
………………………(11)
Pr(Z=2)
If we call this the relative likelihood and assume that X and βK(1) are vectors to
(X1, X2 ……..XK) and β1(1) β2(1), …….. βK(1) respectively. The ratio of relative likelihood
for one unite change in Xί relative to the base category is
then eβ1(1)x1+……+β1(1) (x1+1) +……+βK(1)xK
= eβ1(1)
eβ1(1) x1+….+ β1(1) x1+…..+ βK(1)xK
Thus, the exponential value of a coefficient is the relative likelihood ratio for one unit
change in the corresponding variable (Statacorp .1999) Quoted by Enete (2003) and
Onyekuru (2007).
66
Variable Definition
The type of erosion control practices used was a function of some socioeconomic
characteristics of the farmers as explanatory variable for the study.
These variables are:
•
AGR= Age of the Farmers in (Years)
•
INCM = Annual Income of the Head of Household (Naira)
•
HSZ = Household Size (Numbers)
•
LNDR = Land Tenure (1 Inherited, 0 Otherwise)
•
TOPG =- Slope of the Farm (1= Low, 2 = Medium, 3 = High)
•
LBR = Labour (1 Hired, 0 Otherwise)
•
SZFRM = Size of the Farm under Control (Hectares)
•
RSK = Risk Attitude of the Farmers: Scale from 1= Very Risky,2=Little
Risky,3=Not Risky
•
CSTER = Cost of each Erosion Control Practices (Naira)
•
EROGV = Perception of the Gravity of the Soil Erosion Problem by the Farmers
as 1 = Very Seriously, 2= Little Serious. 3= Not Serious.
3.6.2 Partial Budget Analysis
The partial budget was used to address objective (ii). The partial budget was used
to calculate the expected change in profit for a proposed change in the farm business
resulting from the control of farmland erosion.
67
PARTIAL BUDGET FORMAT
POSITIVE IMPACTS
NEGATIVE IMPACTS
Unit of analysis
Unit of analysis
Added Returns
Added costs
Items 1
Nx
Items 1
Nx
2
.
2
.
.
.
.
.
.
.
.
.
n
Nn
n
Nn
Total Added Returns:
Nx
Total added costs: N X
Reduced Costs
Items 1
Reduced returns
Nx
Items 1
Nx
2
.
2
.
.
.
.
.
.
.
.
.
n
Nn
n
Nn
Total reduced costs: N x
TOTAL POSITIVE IMPACTS
Total Reduced Returns: N x
NX
TOTAL NEGATIVE IMPACTS NX
Net benefit= Total positive impacts –Total negative impacts.
The total positive impacts represents the total benefit while the total negative impacts
connotes the total cost.
68
If the net benefit of the alternative is positive, then the alternative (farmland erosion
control practice) may have some economic advantages. However, if the net benefit is
negative then the alternative would be better put off as it has no economic advantage(
Roth and Hyde 2002).
-List of added returns-This involves identifying any possible means of generating new
revenue streams.
- Reduced Costs-This has to do with identifying the general areas where the choice might
lower expenses.
-Added Costs-This is arrived at by identifying all the general areas in which costs will
increased.
- Reduced returns- In this case, one will have to find out whether revenue will be
decreased or eliminated as result of choosing or using a particular alternative.
3.6.3 Duncan’s Multiple –Range Test
The Duncan‘s multiple range test was used to test hypothesis II to compare the
means of net benefits of different erosion control practices.
The test is given by:
Rp = rp
S2
n
Where rp = least significant studentized range which depends upon the error degrees of
freedom and the number of means of the subset of each erosion control practice.
S2 = Error mean square from the analysis of variance table.
69
n = Sample size for each control practice treatment. (Bewick,V.,Cheek,L.and Ball,J
2004).
3.6.4 Likert Rating Scale Technique
The Likert rating scale was used to analyse objective(iv). To assess the extent of
causes of erosion on the farmland from the farmer‘s perspectives, 3-point likert rating
scale was used. The 3-point likert rating scale was graded as Very Serious (VS) = 3,
Serious (S) = 2, Not Serious (NS) = 1. The mean score of respondents (farmers) based on
the 3-point rating scale was computed;
3+2+1 = 6
3
3
= 2.00 Cut off point
Using the interval scale of 0.05, the upper limit cut-off point was 2.00 + 0.05 =
2.05; the lower limit was 2.00 – 0.05 = 1.95. On the basis of the limit, mean scores below
1.95 were ranked ―Not Serious; those mean value between 1.95 and 2.04 were considered
‗Serious‘ while mean scores that were greater than or equal to 2.05 were considered
‗Very Serious‘.
2.6.5
Profitability Index
Profitability index was used to address part of objective (ii). The more beneficial
and financial attractiveness of the farmland erosion control practices was captured using
Profitability indices. The index attempts to identify the relationship between the costs and
benefits of a proposed project through the use of ratio(Wiki Answer(2010).The
Profitability indices for each erosion control practice was assessed by calculating the ratio
of
Net-benefit to Total cost(Total Negative Impact). Profitability index = Net-
benefit/Total cost.
70
CHAPTER FOUR
4.0
RESULTS AND DISCUSSION
4.1
The Erosion Control Practices Applied By Farmers in the Area.
Agro-engineering findings indicate that farmers in the rural southeastern Nigeria
apply many techniques to conserve soil, control erosion and prevent soil degradation.
(Onuoha, 1985 and Ofomata 1982). To address objective one, table 4.1.1 presents the
frequency, percentage and rank distribution of the erosion control practices applied by
farmers.
From the result below, four erosion control practices were used by farmers in the
study area. They include Multiple Cropping, Construction of bonds, Ridging across the
slope and Cover cropping. Table 4.1.1 below shows that 69 farmers practiced Multiple
Cropping representing 41%, 34 practiced Construction of bonds representing 20%, 30
practiced Ridging across the slope representing 18% while 35 used Cover cropping
(21%). Muhamman and Gungula (2006), in line with this opined that Cover crop in a
mixed cropping system increases farmer‘s insurance against crop failure and erosion.
Suyamto and Howeler (2001) in Indonesia concluded that cultural practices such
as Contour ridging combined with hedgerows could be recommended for planting
cassava, since such practice could reduce soil erosion and give a good cassava yield.
Copper (2008), also saw Multiple Cropping as a low-risk source of food and income for
families whose farm-size is small and who lack the capital to mechanize and expand their
farm.
71
Table 4.1.1 Frequency, Percentage and Rank Distribution of Farmland Erosion
Control Practices.
Erosion Control Practices
Frequency
Percentage
Rank
Multiple Cropping
69
41
1
Construction of Bonds
34
20
3
Ridging Across the Slope
30
18
4
Cover Cropping
35
21
2
168
100%
TOTAL
Source: Field survey 2009
4.1.2 Combination of Erosion Control Practices Applied by Farmers
In other to ensure a proper sustainable environmental and soil quality, farmers applied a
number of combination of farmland erosion control practices. According to USDA
(1994), Improved land management that ensures better resource use and promotes longterm sustainability is basic to future food production and to the economic welfare or rural
communities. Table 4.1.2 therefore reflects the frequency and percentage distribution of
combination of erosion control practices applied by farmers in the area.
On the other hand, there were combinations of erosion control practices applied
by farmers in the area. The result of table 4.1.2 shows that 59 applied two of the control
practices representing 35.1%, 39 farmers applied three of the erosion control measures
representing 23.2% while 4 applied all four control practices in their farmland
representing 2.4%. However, though various combinations could be applied by the
farmers, one was in most cases used as the major control practice depending on the
amount of resources involved. The cost and return analysis discussed in the subsequent
sections was based on this premise.
72
Table 4.1.2 Frequency and Percentage Distribution of Combination of Erosion
Control Practices.
Combination
Frequency
Percentage
Two
59
35.1
Three
39
23.2
Four
4
2.4
Total
168
100%
Source: Field survey 2009
4.1.3 Description of Farmland Erosion Control practices applied by Farmers
Farmers explored and described the four erosion control practices applied as follows;
(i) Multiple cropping – This according to the crop farmers involves the planting of
different crops in the farmland ranging from three to four crops per farmland. Crops
planted by farmers include, maize, yam, cassava, cocoa yam, groundnut, melon, black
beans and cowpea.
(ii) Construction of bonds – From the farmers perspective, the construction of bonds
was done by making cross bars in between ridges and mounds and then planting crops on
the bars or bonds.
Their aim here was to hold in place run off in the farm and
consequently conserves soil. Crops planted by farmers in this control practice include
maize, cassava, tomatoes, bitter leave, Sugarcane and pepper.
(iv)
Ridging across the slope – Farmers practiced this control measure by making
ridges across the slope to block runoffs flowing down the slope and planting crops
on it.
73
Farmers also believed that this practice will help reduce the speed of runoff down the
slope.
(iv) Cover cropping – The respondents described cover cropping as the planting of cover
crops to cover the soil and prevent evapouration and reduce rainfall intensity on the soil.
Such crops planted by farmers to check erosion include; groundnut, cowpea, melon,
sweet potato, cocoa yam, black beans, pineapple etc.
In terms of ranking, Multiple cropping which has the highest frequency of 69
was ranked first seconded by Cover cropping with a frequency of 35. The third ranking
was construction of bonds with a frequency of 34. Ridging across the slope whose
frequency was 30 was ranked fourth and last. It was therefore observed that majority of
the farmers in the area applied Multiple cropping practice to control erosion on their
farmland. Collins (2001) noted that plants provide protective cover on the land and
prevent soil erosion with the following reasons; (a) Plants slow down water as it flows
over the land (runoff) and this allows much of the rain to soak into the ground. (b) Plant
roots hold the soil in position and prevent it from being washed away. (c) They break
the impact of a raindrop before it hits the soil, thus reducing its ability to erode. (d) In
wetlands and on the banks of rivers plants are of particular importance as they slow down
the flow of the water and their roots bind the soil, thus preventing erosion. Akamigbo
(1998) was also of the view that Multiple cropping ensure that the soil is usually
protected by a vegetative cover. The least erosion control practice applied by farmers in
the area (Ridging across the slope) could be because of low availability of sloppy
farmlands in the area.
74
4.2
Costs and Returns for the Erosion Control Practice
The impact of resource management, especially by erosion management on the
farm size, farm output and value of output are deemed serious for the Nigeria agricultural
societies (Titilola 1998). The economic cost of erosion is very difficult to quantify, but it
is definitely very large, Huge sums of money are spent each year repairing damage
caused by erosion or reinforcing existing structures and land against erosion, (Akamigbo,
1999).
A partial budget analysis was conducted to compare the costs and returns of each
erosion control practice in order to ascertain which control measure had the highest netbenefit.
4.2.1 Multiple Cropping Partial Budget
Table 4.2.1. Below presents the partial budget analysis for multiple cropping
erosion control practice.
As shown in the table 4.2.1, the total Positive impacts of
Multiple cropping which include value added to crop output and reduced cost was
N44,7450.78k. The value added to crop output involved total annual income per hectare
from crop output. The reduced cost was nil. The total negative impacts of Multiple
cropping which was made up of added costs and reduced return was N53,496.90k. The
added costs involved the cost of labour and materials. The reduced cost was nil. The netbenefit of Multiple cropping was therefore N393,953.88k. Applying for profitability
indices in this case, table 4.2.1 shows that the total cost which is the total Negative
Impacts was N53,493.90k, while the net-benefits was N393,953.88k. The profitability
index is hence the ratio of Net-benefit to total Negative Impacts (Total Cost). That is
N393,953.88k/ N53,493.90k. The profitability index was therefore 7.36 for Multiple
cropping.
Muhamman and Gungula (2006) observed in northern Nigeria that farm
75
produce obtained from the plots of Maize, Yam and Melon gave more economic returns
than the sole Maize.
Table 4.2.1 Multiple Cropping Partial Budget
POSITIVE IMPACTS
NEGATIVE IMPACTS
Value added to crop output(N)=
Added cost of (labour and materials) (N) =
44,7450.78k
53,496.90k
Reduced cost = NIL
Reduced Return = NIL
TOTAL POSITIVE IMPACTS =N
TOTAL NEGATIVE IMPACTS =
44,7450.78k
N 53,496.90k
Net – Benefit = Total Positive Impact Total Negative impacts
N 44,7450.78 -N 53,496.90k
= N 393,953.88k
Source: Field Survey 2009
4.2.2 Construction of Bonds
Table 4.2.2 shows the cost and returns from construction of bonds. From the
table 4.2.2, the total Positive impacts for Construction of bonds was N42,474.10k while
the corresponding total Negative impacts was N16,358.80k. The net-benefit was N
26,115.30k. That is N42, 474.10 – N16, 358.80. The profitability index for Construction
of Bonds was 1.59. That is N26, 115.30k/ N16, 358.80k.
ASARECA-TUUSI (1998) in East Central Africa also used partial budgeting to reveal
that tie-ridging also called Construction of bonds gave the better net-benefit in maize
based cropping system.
76
Table 4.2.2 Construction of Bonds Net Benefits
POSITIVE IMPACTS
NEGATIVE IMPACTS
Value added to crop output(N) =
Added costs of (labour and materials)
42,474.10k
(N) = 16,358.80k
Reduced cost = NIL
Reduced Return = NIL
TOTAL POSITIVE IMPACTS =
TOTAL NEGATIVE IMPACTS
N 42,474.10k
N 16,358.80k
Net – Benefit = Total Positive Impacts – Total Negative Impacts:
= N 42,474.10k - N16,358.80k
= N 26,115.30k
Source: Field Survey 2009.
4.2.3: Ridging Across the Slope
Table 4.2.3 below presents the net benefit of ridging across the slope. Table 4.2.3
shows that the total Positive impacts of Ridging across the slope which include value
added to crop output and reduced cost was N63,308.33k. On the other hand, the total
Negative impacts which was made up of the added costs of labour and materials and
reduced return was N29, 566.67k. Subtracting the total positive impacts from the total
negative impacts, a net-benefit of N33, 741.66k was observed. From table, the
profitability index for Ridging across the slope can be calculated as the ratio of Net –
benefit to total Negative Impact (Total cost). That is N33,741.66k/N29, 566. 67k.
Therefore the profitability index was 1. 14 for Ridging Across
77
the Slope. Suyamto and Howeler (2001) also reported that terracing of sloping land is a
good way to control erosion even though it requires a lot of labour, time and capital.
Table 4.2.3: Ridging Across the Slope Partial Budget
POSITIVE IMPACTS
NEGATIVE IMPACTS
Value added to crop output(N) =
Added costs of (labour and materials)
63,308.33k
(N) = 29,566.67k
Reduced cost = NIL
Reduced Return = NIL
TOTAL POSITIVE IMPACTS =
TOTAL NEGATIVE IMPACTS =
N 63,308.33k
N 29,566.67k
Net – Benefit = Total Positive Impact Total Negative Impacts
N 63,308.33k - N 29566.67k
= N 33,741.66k
Source: Field Survey 2009
4.2.4 Cover Cropping
Table 4.2.4 present the partial budget for cover cropping erosion control. From
table 4.2.4, it was observed that the total positive impacts of Cover cropping was
N9,330.00k and the total negative impacts was N8, 438.90k. The net-benefit which is
total positive impacts – total negative impacts was N891.10k. This net –benefit was used
to capture the profitability index for Cover cropping. This was done by dividing the Netbenefit by the total Negative Impacts. Hence N891.10k/N8,438.90k. The profitability
index of 0.10 was
78
therefore captured for Cover cropping.
Cover crops according to Muhamman and
Gungula (2006) and PENNSTATE (1995-2010), have a lot of economic benefits such as
controlling erosion, improving soil fertility, reduction in the use of inorganic fertilizers,
herbicides, weed and insect control cost, protecting ground water, scavenging residual
nitrate and high economic return to the farmers.
Table 4.2.4 Cover Cropping Partial Budget
POSITIVE IMPACTS
NEGATIVE IMPACTS
Value added to cropoutput(N) = 9,330.00
Added costs of labour and materials(N)=
Reduced cost = NIL
8,438.90k
Reduced Return = NIL
TOTAL POSITIVE IMPACTS
TOTAL NEGATIVE IMPACTS
= N 9,330.00
=
N 8,438.90k
Net – Benefit = Total Positive Impacts – Total Negative Impacts:
= N 9,330.00 - N 8438.90k
= N 891.10k
Source: Field Survey 2009
The result of the Partial budget analysis for each erosion control practice showed
that the Net-benefits of Multiple cropping, Construction of bonds, Ridging Across the
slope and Cover cropping were N393, 953.88k, N26, 115.30k, N33, 741.66k and
N891.10k respectively. Multiple cropping therefore has the highest Net-benefit of
N393,953.88k compared to other control practices. Meanwhile, the Profitability indices
results for Multiple cropping, Construction of bonds, Ridging across the slope and Cover
79
cropping were 7.36, 1.59, 1.14 and 0.10 respectively. It is therefore more beneficial to
invest in Multiple cropping than other forms of erosion control measures. Copper Wikki
(2008), concluded that Multiple Cropping uses renewable natural resources to control
erosion, provide food, income and livelihood for current and future generations.
4.2.5 Duncan’s Multiple Range Test
The Duncan‘s multiple range test is a comparison test tool that can capture the
significant difference in the means of net-benefits of different erosion control practices.
Duncan‘s tests was used to test hypothesis II to compare the means of net-benefits of
different erosion control practices.
Table 4.2.5.1 compared the means of net –benefits of the erosion control practices
used by the farmers. From the analysis of variance table 4.2.5.1, below the P-value which
tests the overall model to determine if there is a difference in means between net benefits
of different erosion control practices, was small. In this case, since the P-value is small (P
= 0.0002), it can be concluded that there is evidence that there is statistically significant
difference in the means of net-benefits of erosion control practices.
In order to determine where the differences lie, that comparison was performed by
the Duncan‘s Multiple Range test at the alpha = 0.05. Notice the grouping labels ―A‖ and
―B‖ in the table above. There was only one mean associated with ―A‖ group and that is
Multiple cropping. This indicates that the mean for Multiple cropping is significantly
larger than the mean of all other groups. There are three means associated with the ―B‖
group – they are Ridging Across the slope, Construction of bonds and Cover-cropping
erosion control.
Therefore, the Duncan‘s comparison concludes that the mean for Multiple
cropping erosion control is significantly higher than the means of Ridging Across the
80
slope, Construction of bonds and Cover-cropping erosion control and that there is no
significant difference between Ridging Across the slope, Construction of bonds and
Cover-cropping erosion control. Abu-Hamdeh (2003) also used Duncan‘s Multiple Range
test to compare means of bean and barley yields by type of weed control system for four
tillage systems in Jordan. The details of the Duncan‘s multiple range test are found in the
appendix.
Table 4.2.5.1 Duncan’s Multiple Range Test for Net-Benefit
Duncan grouping
Mean
N
Erosion control
A
252740
69
Multiple cropping
B
35242
30
Ridging across the slope
B
29456
34
Construction of bonds
B
6631
35
Cover cropping
Source: field survey 2009
4.3 Socioeconomic Factors Affecting Farmer’s Use of Particular Erosion Control
Practices
The dependent variables (Y) were the erosion control practices which are
designated 1,2,3,4 for multiple cropping, construction of bonds, ridging across the slope,
and cover cropping respectively. These dependent variables are determined by maximum
likelihood.
The socioeconomic factors affecting the use of a particular farmland erosion
control practices as a concept of resource use sustainability can best be captured using
81
multinomial logit model. The multinomial logit regression is used when the dependent
variable in question which is the erosion control practice is nominal and consist of more
than two categories. Farmer perception of the problem of soil erosion, its costs and
benefit is key to determine the usage of soil erosion control practices (Franco and Cala
Trava 2006).
Table 4.3 presents the results of Multinomial logit regression analysis of the
socioeconomic characteristics affecting the farmers use of multiple cropping,
Construction of bonds, Ridging across the slope and Cover cropping in Enugu State. The
explanatory powers of the factors as reflected by pseudo-R2 seem low (24%), but this is
not uncommon in cross sectional analysis. The overall goodness of fit as reflected by
Prob>chi2 was however good (<0.0000).
In comparison with age, the probability that farmers engage in planting cover
crops (step 4) as against construction of bonds (step 2) was negatively and highly
significantly related with the age of the farmers. The coefficient and t-value was -0.117
and 3.03 for Cover cropping. The t-value was significant at 1% and consistent with a
prior expectations. As the age of the farmers increases, their probability of using Cover
cropping decreases compared with the use of construction of bonds. This suggests that
young farmers are more energetic to cope with the laborious nature of the erosion control
practice as against construction of bonds. This is in line with Ahmed, Atry and Elham
(2009).
Household size (Hhs): Household size positively affected farmers willingness to adopt
Multiple cropping, and Making ridges across the slope. The coefficient and t-value for
Multiple cropping are 0.56 and 3.390; while the values for making of Ridges across the
slope were 0.484 and 2.770. The t-values were significant at 1%. It implies that as the
82
household size gets bigger, the probability that farmers will engage in Multiple cropping
and making ridges across the slope increases. Family labour could be an important
source of farm labour for execution of these operations that aid in erosion control. This is
in line with Franco and Calatrava-leyval, Franco Martinez and GonzalenzRoa, (2007)‘s
view that continuity of sons and relatives in farming is an important factor in the
adoptions of soil conservation practices.
Cost of erosion control was positively related to Multiple cropping. Its coefficient and tvalue for Multiple cropping are 0.001 and 2.390 respectively.
The t-value was
significant at 5%. It means that as the cost of erosion control increases, farmers will be
willing to engage in Multiple cropping. However, farmers are choosing multiple cropping
instead of construction of bonds as costs increases because Multiple cropping though
capital and labour intensive increases their insurance against crop failure and erosion as
well as optimization of production from small plots thus helping farmers cope with land
shortage since a variety of crops are grown on the same of piece of land. Diverse foods
outputs are also obtained through Multiple cropping, hence providing a chance of choice
for using food commodities. From the market point of view, as farmers are getting more
than one crop simultaneously, even if the selling price of one commodity is less in the
market, the other will be there to compensate. Omar (2011) also reported in Somali that
Multiple cropping requires a lot of capital for the smooth running of farming activities as
well as intensive labour that can be used in cultivation and management practices that
will be undertaken. He also concluded that Multiple cropping systems results in efficient
use of land resources thus providing year – round coverage of crop land hence reducing
erosion and sustaining top soil.
83
Table 4.3.0
Result of Multinomial Logit Regression Analysis of the
Socioeconomic Characteristics Affecting the Farmers Use of
Multiple Cropping, Construction of Bonds, Ridging Across the
Slope, and Cover Cropping in Enugu State
Multiple cropping, Ridging across the slope, Cover Cropping
Variables
Age
Income
Hhs
Landtr
Labour
Sfuctr
Costec
Erogv
Intercept
1
3
4
-0.062
-0.064
-0.117
(-1.850)
(-1.760)
(-3.020)***
1.130
-2.970
-5.960
(0.820)
(-1.300)
(-1.840)
0.562
0.484
0.299
(3.390)***
(2.770)***
(1.630)
-0.040
-0.079
-0.526
(-0.060
(-0.110)
(-0.740)
0.677
-0.355
0.096
(1.110)
(-0.570)
(0.140)
-0.794
-0.446
0.148
(-1.350)
(-0.446)
(0.240)
0.0001
0.0001
-0.0001
(2.390)**
(1.770)
(-1.170)
0.499
-0.945
-0.396
(0.940)
(-1.710)
(-0.700)
-1.237
2.571
5.475
(-0.570)
(1.120)
(2.280)**
Statistics: Ch2 = 108.91
Prob>Chi2
= 0.0000
Pseudo R2
= 0.2449
Numb of Obs =168
Note: Construction of Bonds (2) is the comparison category.
Figures in parentheses are Z-ratios.
84
*** denotes P≤0.001,
** denotes 0.01< P≤0.05
Source Field Survey 2009
4.4.
Possible Causes of Erosion on the Farmland from the Farmers Perspective.
The relationship between climate and soil erosion is fairly well known and for
south eastern Nigeria, especially Enugu state, rainfall and soil type constitutes the
dominant sub-factor (Ofomata 1985-88). Table 4.4.1 showed the percentage causes of
erosion on the farmland.
From table 4.4.1 below, 95.2 percentages of the farmers said yes to rainwater as a
possible cause of erosion on farmland while only 4.8 percent said no. Onyeguocha (1980)
stated that the agent of soil erosion in Anambra and Enugu state is rainwater. About 70
percent of them said no to deforestation. Ofomata (1988) observed that human erosion
action is made manifest on the earth‘s surface through his agricultural activities,
especially through his clearing of the original vegetation.
For soil type, 94.6% of the farmers agreed that it was a cause of erosion while only 5.4%
of them said no to soil type. This goes with Ofomata (1988) who noted that the unique
dimension which soil erosion is attained by southeastern Nigeria is related in very direct
way to the lithological composition of the soils of the area. About 94% said yes to slope
of the farm as one of the causes of erosion. Ofomata (1985) also suggested that other
factors that play significant role in soil erosion in Anambra and Enugu state include
topography (relief/slope), climate and surface material. World Bank (2001) also noted in
China that, mass wasting which is the down slope movement of rock and sediments occur
mainly on a gentle slope.
85
Further, 45.2% of the farmers indicated excessive bush burning as a cause of erosion. For
population density, 46.4% of farmers said yes while 53.6% said no. 58.3 of the farmers
said yes to poor road construction as a cause of erosion while the remaining 41.7% of the
farmers disagreed with it. As regards Poor farming system, 82.7% of the farmers were of
the view that it causes erosion on the farmland while 17.3% of them did not agree to poor
farming system. In the case of Quarrying of sand, 48.3% of the respondents said yes to it
as a cause of erosion but 51.8% said no that quarrying of sand does not cause erosion on
farmland. Akamigbo (1988), suggested that Anthropogentic activities which either
initiate or aggravate soil erosion in include poor road construction, indiscriminate house
construction across natural drainage routes, quarrying of sand and gravels, bush burning,
indiscriminate free felling and poor farming techniques.
The field survey also showed that 37.5% of the farmers in the area said yes that crops that
attracts human traffic can cause erosion while 62.5% of them disagreed that is cannot
cause erosion on farm. The Nigerian Institute of Social and Economic research (NISER,
1988) opined that the choice of crop that are labour intensive or attract human traffic may
cause severe soil erosion.
On the other hand, 88 farmers representing 52.4% believed that overgrazing could cause
soil erosion on the farm, but 47.6% said no to overgrazing as possible cause of erosion.
Other possible causes of erosion on the farmland as observed by the farmers include
cattle hooves of which 2.4% agreed to it while the rest 97.6% said no to overgrazing.
86
Table 4.4.1 Frequency and Percentage Distribution of the Possible Causes of
Erosion on the Farmland.
Causes of Erosion
Frequency
Percentage of
Frequency
Percentage of
of Yes
Yes
of No
No
1.
Rain Water
160
95.2
8
4.8
2.
Deforestation
113
67.3
55
32.7
3.
Soil type
159
94.6
9
5.4
4.
Slope of the Farm
158
94
10
6
5.
Excessive bush burning
76
45.2
92
54.8
6.
Population Density
78
46.4
90
53.6
7.
Poor Road Construction
98
58.3
70
41.7
8.
Poor Farming System
139
82.7
29
17.3
9.
Quarrying of Sand
81
48.2
87
51.8
10.
Crops that attract human
63
37.5
105
62.5
traffic
11.
Gods
13
7.7
155
92.3
12.
Overgrazing
88
52.4
80
47.6
13.
Others: Cattle hooves
4
2.4
164
97.6
Source: Field Survey 2009
87
4.4.2 Causes and Extent of Cause of Erosion as Perceived by the Farmers.
The conservation of natural resources, however, entails a better knowledge of the
limitations imposed by the natural and man- made misuse of the environment as well as
the need for ecological balance (Titilola, 1998). The extent of causes of erosion on the
farmland can be assessed using a 3-point Likert scale rating.
Table 4.4.2.1 revealed that the effects of Rainwater, Deforestation, Soil type,
Slope of the farm, Poor road construction and Indiscrimate house construction on the

farmland in the area were very serious. This was reflected in their high mean ( x ) values
ranging from 2.42, 2.26, 2.49, 2.37, 2.35 and 2.16 respectively. The result also shows that
factors such as population density and poor farming system were serious causes of

erosion with moderate mean ( x ) values of 1.99 and 2.01 respectively.
Furthermore, other factors from the table as Excessive bush burning, Quarrying of sand,
Crops that attracts human traffic, Gods, Overgrazing and others like cattle hooves were

not a serious cause of erosion in the area. This was capture in their low mean ( x ) values
such as 1.54 (Excessive bush burning), 1.64 (Quarrying of sand), 1.42 (Crops that attracts
human traffic), 1.16 (Gods), 1.74 (Overgrazing and 1.02 (Cattle hooves).

In general, the high mean ( x ) values of the very serious causes of erosion on the
farmland from the farmer‘s perspective were expected. This agrees with Lal (1990) and
Ofomata (1986) who noted that rainfall leads to leaching and run off which is the central
agent in soil erosion system. Amechi (1977), Edward(1993) and Copper Wikki (2009)
also reported that soil erosion is intensified by human activity which has been significant
88
in the recent periods as man began to step up the exploitation of natural resources such as
deforestation. The unique dimension which soil erosion has attained in south eastern
Nigeria is related in very direct way to the lithological composition of the soils of the
area. This derives from their parent materials which are mainly soft sandstone formations
of cretaceous and tertiary age (Ofomata 1988). The opinions of Akamigbo (1999) and
Ofomata (1988) in line with this study stated that surface configuration (relief/slope) aids
runoff, sheet erosion and gulling. Soil loss due to erosion course is also dependent on the
amount and intensity of rainfall, the slope and the characteristics of the soil (Suyamta and
Howeler 2001).
A similar view of this study was shared with Akamigbo (1988) where her
submitted that Anthropogenic activities which either initiate or aggregate soil erosion in
the old Anambra State include poor raod construction, indiscriminate house construction
across natural drainage routes, quarrying of sand and gravels, bush burning, urbanization
and industrialization. Soil erosion is aggravated by such factors as poor farming systems,
soil management practices and poverty stricken farmers (Akamigbo and Titilalo (1998)
and Zhita and Xuezhen (2004). This study also agrees with the report of Ofomata (1985)
that besides civil anthropogenic activities, population density also play significant role in
soil erosion in Enugu and Anambra State.
Moreover when land is overused by animal activities, there can be mechanical erosion
and also removal of vegetation leading to erosion (Wikipedia 2009). Copper Wikki
(2009) also noted that cattle and sheep compact the soil and remove vegetation which
may lead to soil erosion.
89
Table 4.4.2.1: Mean and Standard deviation Distribution of the Perception of
Extent of Causes of Farmland Erosion by the Farmers.
S/N Causes of Erosion
X
Std Dev
Remarks
1.
Rain Water
2.42
0.652
Very Serious
2.
Deforestation
2.26
0.711
Very Serious
3.
Soil type
2.49
0.683
Very Serious
4.
Slope of the Farm
2.37
0.705
Very Serious
5.
Excessive bush burning
1.54
0.733
Not Serious
6.
Population Density
1.99
0.781
Serious
7.
Poor Road Construction
2.35
0.735
Very Serious
8.
Indiscrimate house construction
2.16
0.857
Very Serious
9.
Poor farming system
2.01
0.774
Serious
10.
Quarrying of Sand
1.64
0.719
Not Serious
11.
Crops that attract human traffic
1.42
0.563
Not Serious
12.
Gods
1.16
0.442
Not Serious
13.
Overgrazing
1.74
0.798
Not Serous
14
Others: Cattle hooves
1.02
0.133
Not Serious
Source: Field Survey 2009
90
CHAPTER FIVE
5.0
SUMMARY, CONCLUSION AND RECOMMENDATIONS
5.1 SUMMARY
Soil erosion is one manifestation of soil degrading processes that results in
reduced soil quality and productivity. There is therefore the need for combating it so as to
halt the accelerating trend of soil degradation, to maintain soil productivity and to
contribute to the food security of current and future generations. This is the basis for this
study.
The specific objectives of the study are to; identify and describe the erosion
control practices (or combination of practices) applied by farmers in the area, determine
the net-benefit of erosion control practices, determine the socio-economic factors
affecting the farmer‘s use of a particular erosion control practices, identify from the
farmer‘s perspective the possible causes and extent of cause of erosion on the farmland
and make recommendations for improving erosion control practices based on the
findings.
The study was carried out in Enugu State, which is made up of three agricultural
zones. Two local government areas that have predominantly sandy soil were purposively
selected from each zone based on the soil type map of Enugu State. A random sampling
of two communities and fourteen crop farmers from each community in each local
government selected was done. This made the total sample size of 168 farmers. Primary
data were collected by the use of structured questionnaire and interview schedule. Data
91
were analyzed by the use of descriptive statistics, Multinomial logit model, Partial budget
analysis and Duncan‘s Multiple range test.
The result of the analysis showed that four erosion control practices were applied
by the farmers. These include Multiple cropping (41%), Construction of Bonds (20%),
Ridging across the slope (18%), and Cover cropping (21%). Some farmers combined two
or more erosion control practices but in most cases one was used as the major control
practice depending on the amount of resources involved. The combination rates were, one
– 39%, two 35.1%, three 23.2% and four-2.4%.
On the coverage, the Net benefit of Multiple cropping was N393,953.88,
Construction of Bonds – N26,115.30k, Ridging across the slope – N33,741.66k, and
Cover cropping N891.10k. The corresponding profitability indices for the erosion control
practices were; 7.36 for Multiple cropping, 1.59 for Construction of bonds, 1.14for
Ridging across the slope and 1.10 for Cover cropping.
There was statistical significant different between the means of net-benefits of
erosion control practices with that of Multiple cropping being significantly larger than the
means of all others at 5%.
The Multinomial logit Regression analysis showed a seemingly low explanatory
power of the factor as reflected by Pseudo- R2 (24%) which is not uncommon in cross
sectional analysis. The overall goodness of fit as reflected by prob> Chi2 was however
good (<0.0000). The age of the farmers negatively and significantly affected the farmer‘s
probability of using Cover cropping at 1% as against Construction of bonds. Household
size positively affected farmers willingness to adopt Multiple cropping and making ridges
across the slope at 1% probability level. However, household size is very importance in
adoption of erosion control practices as it provides family labour used in the control
92
measures. Cost of erosion control was positively and significantly related to Multiple
cropping at 5% probability level.
Likert Rating Scale Technique showed high mean (X) values for rainwater (2.42),
Deforestation (2.26), Soil type (2.49), Slope of the farm (2.37), Poor road construction
(2.35) and Indiscriminate house construction as very serious causes of erosion in the
study area. The rating scale equally captured moderate mean (X) values for Population
density (1.99) and Poor farming system (2.01) as serious causes of farmland erosion.
Other factors like Excessive bush burning, Quarrying of sand, Crops that attracts human
traffic, gods, Overgrazing and Cattle hooves had low mean (X) values.
Possible causes of erosion on the farmland from the farmer‘s perspective include
Rainwater – (160,95%), Deforestation – (133,67.3%), Soil type – (159, 94.6%), Slope of
the farm – (158,94%), Excessive bush burning – (76,45.2%), Population Density –
(78,46.4%), Poor road construction – (98,58.3%), Poor farming system – (139,82.7),
Quarrying of sand – (81,48.2%), Crops that attracts human traffic – (63,37.5%), gods –
(13,7.7%), Overgrazing – (88,52.4%), Cattle hooves – (4,2.4%).
5.2 Conclusion
The net-benefit and profitability index of Multiple cropping erosion control
practice was shown as the highest compared to Construction of bond, Ridging across the
slope and Cover cropping which had the lowest value.
The use of Cover cropping erosion control practices as against Construction of
bond was negatively and significantly related to the farmer‘s age, as shown by
Multinomial logit model. Meanwhile, Household size positively and significantly
affected the farmer‘s use of Multiple cropping and Ridging across the slope compared to
Construction of bonds. However the Cost of erosion control also influenced positively
93
and significantly the farmer‘s use of Multiple cropping. The Likert scale rating captured
rainwater, deforestation, soil type, slope of the farm, poor road construction,
indiscriminate house construction and poor farming system as the major causes of erosion
on the farmland as persived by the farmers in Enugu State.
Despite these challenges faced by the poor farmers in controlling farmland
erosion, the study revealed that it is still beneficial to practice the above erosion control
measures in Enugu State. It is therefore recommended that incentives, an extension
service and technical training be adequately provided to the farmers for increased
sustainable crop production and environmental quality.
5.3 Recommendations.
 Farmers should be encouraged to combine sound methods of soil management
with other methods and inputs of modern agriculture to obtain satisfactory
production on a sustained basis.
 The government should pass new legislation to establish a soil erosion control
agency and extension programme and fund the work at a high enough level to
obtain satisfactory results.
 Farmers should have a change of attitude in order to avoid the possible causes of
erosion on their farmland. This may be achieved by planting more trees, avoiding
deforestation, and overgrazing as well as encouraging the use of those sustainable
agricultural practices.
 In order to bridge the gap of understanding between government, policy makers
and farmers,there should be an organized co-operative association of landowners,
tenants and farmers that will lead ultimately to better conservation and land use.
94
 The poor farmers that dominate the area should be assisted by the government by
providing liberal agricultural credit, better seed and fertilizer, equipment hire and
purchase assistance in order to either improve soil directly or make it possible for
farmers to use effective erosion control measures.
 Extension agents should provide more packages on farmland erosion control
practices that will equip the farmers with the technical know-how to face the
challenges of erosion on their farms.
95
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Fig 2: SOIL EROSION MAP OF SOUTH EASTERN NIGERIA.
Source: Ofomata, (1988)
LEGEND
Slight sheet Erosion
Moderate Sheet Erosion
Severe Seheet Erosion
Slight Gullly Erosion
Severe Gully Erosion
Coastal Erosion
112
Adapted and modified from GSN 2215
Fig.3: POTENTIAL EROSION MAP OF SOUTH EASTERN NIGERIA.
Source: Ofomata, (1988)
LEGEND
A
HIGH POTENTIAL
Unconsolidated Sediments of Quaternary Alluvium
Unconsolidated Sediments of Quaternary Coastal plains
Sands
Weak Quaternary Sediment of Tertiary to Cretaceous
Lignite Formation
B
MODERATE POTENTIAL
Crystalline Rocks of the Basement Complex and
Associated Younger Intrusive Igneous Rock
Cretaceous Sediments of the Niger and Benue Valleys and
Cross Rive Plains
113
SOIL TYPES
IN
ENUGU
STATE
Fig. 4: SOIL TYPE MAP OF ENUGU STATE
Source: ENADEP, (2008).
114
APPENDIX
ANOVA Procedure for Duncan’s Multiple Range Test
4.2.5
The ANOVA Procedure
Class Level Information
Class
Levels
=Erosion_control
Values
4
Construction_of_Bonds Cover_cropping Multiple_cropping
Ridging_Across_the_scope
Number of observations
168
08:03 Friday, January 22, 2010
2
The ANOVA Procedure
Dependent Variable: Net_benefit
Net_benefit
Source
DF
Sum of
Squares
Mean Square
F Value
Pr > F
Model
3
2.1587666E12
719588850467
6.48
0.0004
Error
164
1.8209026E13
111030649146
Corrected Total
167
2.0367793E13
R-Square
Coeff Var
Root MSE
Net_benefit Mean
0.105989
283.7305
333212.6
117439.8
Source
Erosion_control
DF
Anova SS
3
2.1587666E12
Mean Square
F Value
Pr > F
719588850467
6.48
0.0004
08:03 Friday, January 22, 2010
3
The ANOVA Procedure
Levene's Test for Homogeneity of Net_benefit Variance
ANOVA of Squared Deviations from Group Means
Source
Erosion_control
Error
DF
Sum of
Squares
3
164
2.645E24
2.04E25
Mean
Square
F Value
Pr > F
8.818E23
7.09
0.0002
1.244E23
08:03 Friday, January 22, 2010
The ANOVA Procedure
Level of
Erosion_control
N
---------Net benefit--------Mean
Std Dev
4
115
Construction_of_Bonds
Cover_cropping
Multiple_cropping
Ridging_Across_the_slope
34
35
69
30
29455.882
101638.653
6631.143
3850.502
252739.855
512289.872
35241.667
27314.617
08:03 Friday, January 22, 2010
5
The ANOVA Procedure
Duncan's Multiple Range Test for Net_benefit
NOTE: This test controls the Type I comparisonwise error rate, not the experimentwise error rate.
Alpha
0.05
Error Degrees of Freedom
164
Error Mean Square
1.11E11
Harmonic Mean of Cell Sizes 37.80387
NOTE: Cell sizes are not equal.
Number of Means
Critical Range
2
151333
3
159289
4
164593
Means with the same letter are not significantly different.
116
UNIVERSITY OF NIGERIA, NSUKKA
FACULTY OF AGRICULTURE
DEPARTMENT OF AGRICULTURAL ECONOMICS
Dear Respondent,
REQUEST FOR RESPONSE TO QUESTIONNAIRE
I am a post-graduate student of the above named department and university,
currently carrying out an M.Sc Research works on “Economic Study of Farmland
Erosion Control Practices in Enugu State”.
You have been selected as one of the respondents to supply the required
information for the study to ensure its success.
It is purely an academic research work and all information supplied by you will be
treated confidentially.
I therefore solicit for your honest co-operation to respond as objective as possible
to the questions.
Thanks for your anticipated co-operation
Yours Sincerely,
Eze, Silas .O.
Instruction-Please Tick (√) for any correct option you have chosen.
SECTION A: SOCIOECONOMIC CHARACTERISTICS OF THE
RESPONDENTS AND EROSION CONTROL.
1. Agricultural Zone……………………………………………………………………
2. Local Government Area……………………………………………………………….
3. Village/Community………………………………………………………………….
4. Date of Interview………………………………………………………………………
5. Name………………………………………………………………………………….
(if possible)
117
6. Age…………………………………………………………………………………
7. Gender. Male
Female
8. Marital Status: Single
Married
Widow
Divorced
9. Educational level of the farmers:
None
Primary
Secondary
Tertiary
10. What is the size of your household…………….……………………………………..
11. What is your major occupation……………………………………………………......
12. How much is your annual income from primary and major occupation
N……………………………………………………………………………………….
13. How did you acquire land: Inherited
Otherwise
14. What is the slope of your farm: Low
Medium
High
15. What is the size of your farmland under Erosion control; (hectares)………………….
16. How do you perceive the gravity of soil erosion problem: 1 = Very serious
2 = Little serious
3 = Not serious
17. How would you describe the risk nature of the erosion control: 1 = Very risky
2 = Little risky
3 = Not risky
18. What is the source of labour: 1 = Hired
SECTION B:
2 = Otherwise
IDENTIFICATION AND DESCRIPTION OF EROSION
CONTROL PRACTICES OR COMBINATION OF
PRACTICES BY FARMERS
1. Do you observe any form of Erosion on your farmland: Yes
2. Are you willing to pay for erosion control on your farm land: Yes
3. Do you practice any of the following erosion control measures?
No
No
118
Erosion Control Practice
Yes
Construction of bond
Grassing of waterways
Multiple cropping
Hedge-row planting
Ridging across the slope
Cover cropping
Others: specify
----------------------------------------------------------------------------------------------------------------------------------
4. If yes how do you practice any of the following?
Erosion Control Practice
Construction of bond
Grassing of waterways
Multiple cropping
Hedge – row planting
Ridging across the slope
Cover cropping
Others: specify
--------------------------------------------------------------------------------------------------------------------------------------------------------------
How (Description)
No
119
SECTION C: POSSIBLE CAUSES OF EROSION ON THE FARM LAND FROM
THE FARMERS PERSPECTIVE
1. Do you believe there are factors responsible for erosion on the farmland:
Yes
No
2. Does the following cause erosion on the farmland
Cause
Yes
No
Rain water
Deforestation
Soil type
Slope of the farm
Excessive bush burning
Population density
Poor road construction
Poor farming system
Quarrying of sand
Crops that attracts human traffic
Gods
Overgrazing
Others: specify
--------------------------------------------------------------------------------------------------------------------------------
3. To what extent do the following cause erosion on the farmland
Causes
A
Rain water
B
Deforestation
C
Soil type
D
Slope of the farm
Not Serious
Serious
Very Serious
120
E
Excessive bush burning
F
Population density
G
Poor road construction
H
Indiscriminate house construction
I
Poor farming system
J
Quarrying of sand
K
Crops that attracts human traffic
L
gods
M
Overgrazing
N
Others: specify
SECTION D: COSTS AND RETURNS
1. How much do you pay for hired labour per day
(Mondays)……………………………………………………………………..........
2. How much do you pay for inputs such as:
a. Seeds (N)--------------------------------------------------------------------------------------b. Fertilizer (N)----------------------------------------------------------------------------------c. Materials (N)---------------------------------------------------------------------------------3. How much do you pay for the following control practices: per year/hectare
S/N
EROSION CONTROL PRACTICE
I
Construction of Bond
II
Multiple cropping
III
Hedge-row planting
IV
Ridging across the slope
V
Cover cropping
COST (N)
121
4. How much do you realize from the following practices: per year/hectare
S/N
EROSION CONTROL PRACTICE
I
Construction of Bond
II
Multiple cropping
III
Hedge-row planting
IV
Ridging across the slope
V
Cover cropping
INCOME (N)
5. How much does each of the control practice add to crop output per year/hectare
S/N
EROSION CONTROL PRACTICE
I
Construction of Bond
II
Multiple cropping
III
Hedge-row planting
IV
Ridging across the slope
V
Cover cropping
VALUE ADDED TO OUTPUT
6. How much do you sell a unit of crop output?------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------7. If land is not inherited how much do you pay per year/hectare?----------------------8. Do you use machineries in your farming operations? 1 = Yes
2 = No
9. Are you aware of any public programmes on erosion control?, -1- yes
10. Do you have any contact with Extension Agents? 1-yes
11. If yes how often per year? 1 not often
2-often
2 No
2-No
3 very often
2. No