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Regional Environmental Technical Assistance 5771
Poverty Reduction & Environmental Management in Remote Greater Mekong Subregion Watersheds
Project (Phase I)
UPLAND AGRICULTURE
Regional Report
By
Eija Pehu
CONTENTS
1.
General Features of the Agricultural Sector in GMB Countries
3
2.
Shifting Cultivation Systems
5
3.
Extent of Soil Erosion and Current Soil and Water Conservation Measures in
Southeast Asia
8
3.1
Introduction
8
3.2
Erosion rates for various land uses and terrain types:
8
3.3
Soil and water conservation practices:
9
4.
Experiences of Upland Development Options
14
4.1
Systems analysis-approach
14
5.
Pressures and Constraints to Change Upland Farming Systems
15
6.
ICRAF and Alternatives to Slash and Burn
16
7.
Conclusions
18
References
24
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1. GENERAL FEATURES OF THE AGRICULTURAL SECTOR IN GMB COUNTRIES
Agriculture is the most important economic sector in GMS countries. On average 75% of the population is
engaged in agriculture and aquaculture. The agricultural policies viewing the sector having a role in feeding
the domestic demand (food self-sufficiency) or in generating the income to purchase food (food security) vary
from country to country. E.g. Laos and Vietnam stress food self-sufficiency whereas Thailand has further
liberalised the agricultural economy aiming at food security. One unifying feature regarding agriculture is that
export oriented agriculture is perceived as the engine of economic growth following the Thailand model. In this
context Lao and Myanmar are the poorest performers in the GMS. Both are featured by poor infrastructure,
low human resources development and weak linkages to global economy. Because of the prolonged centrally
planned economical strategies these two countries fell behind the other GMS countries in development. This
is reflected in the Human Development Index (Lao 0.24, Myanmar 0.38, China 0.61, Thailand 0.68, ESCAP,
1998). Cambodia is also among the poor performers because of its recent history of conflict and the present
political instability.
In response to these imbalances ADB initiated a program of regional economic integration in 1992. In total
100 subregional projects were identified and a special working group on Economic Cooperation for
Cambodia, Laos and Myanmar was established in 1994 in preparation for the ASEAN. The major goals were
to assist the countries in market economy transition, encouragement of private investment and in developing
a special market economy zone between the GMS countries. The initiative can be considered rather
successful as trade within the basin grew faster than with the world from 1985 to 1995. Economic integration
and cross-border trade are important for upland development because many of the envisioned export
commodities come from upland agriculture such as coffee, tea, rubber, fruits and vegetables.
In the following is a table summarising key features of the agricultural sectors in the GMS countries.
Table 1. National features of the agricultural sector in the GMS
Cambodia
Laos
Myanmar
Thailand
Vietnam
Yunnan
50% of GDP
Half of the 2,3
million ha’s
cultivated
36% of GDP
No. 1 rice
exporter
Arable land 7
million ha
94%
mountainous
areas
1,9 million ha’s
of 2,4 cultivated
300 000 ha of
vegetation
cleared/year
Potential to
expand arable
land
Upland food
crops 60% of
rice production
value
Intensive rice
production in the
delta
Upland rice
100 000 ha’s
50 000 ha of
upland rice
Upland rice 20%
of total rice
production and
35% of the area
2,5 million
engaged in
shifting
cultivation
Important
upland cash
crops cassava
and rubber
Soil degradation
in the Central
Highlands
Upland
agriculture
subsidized
Increasing
plantation
agriculture
Land in the
South demand
in the North
Export potential
for upland crops
Well developed
agroindustry
Major rice and
significant coffee
exporter
Erosion prone
soils
Land mines
Potential for
upland crop
exports
Weak support
services to the
farmers
High input use in
some upland
crops
Agricultural GDP
grow 5%/year
Rich in
biodiversity
1 million people
engaged in
shifting
cultivation
Rather good
manufacturing
capacity
Sustainable
traditional
farming systems
Foreign
investment in
agriculture
encouraged
2. SHIFTING CULTIVATION SYSTEMS
Shifting cultivation (swidden agriculture) systems have been and are being practised by upland rural
communities throughout the world. This is simply for the reason that fire is the most efficient and cheapest
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way to clear bush or woody vegetation for crop production. The shifting cultivation systems can be divided into
two broad categories: pioneering systems and rotational swidden systems. In the pioneering shifting
cultivation a plot of forest is cleared and cultivated as long as the soil fertility is adequate to give a satisfactory
crop yield. After the fertility declines below this the farm-family moves to another forested area and abandons
the first one. Usually the cultivation period is 3 to 4 years followed by a fallow of 7 to 20 years depending on
soil fertility. As economic integration proceeds many mixed cultivation systems have emerged which mix
sedentary land use with shifting cultivation.
One of the advantages of the shifting cultivation systems is the superior quality of agricultural produce
recognised also by people living in the plains. Furthermore, there is low requirement of equipment and capital
(need only hand tools, whereas in the plains need harrow, plough, etc). Variable costs of production are also
low in the uplands (mainly seeds and labour), whereas in the plains the farmers need a buffalo, inputs etc.
Upland systems are also featured by good nutritional status of the population because of the diverse diet
(over 200 animal and forest products identified). Moreover, there is great potential to exploit the nature for
housing materials, paper making, food security, etc. Last but not least the shifting cultivation systems maintain
community spirit and mutual support systems.
There are, however, also major disadvantages to the shifting cultivation systems. One of the major ones is soil
erosion if the fallow period is too short and simplification of the ecosystem leads to reduction in biodiversity.
There is also low productivity to labour when the fallow period gets shorter and low capacity and motivation
for capitalisation because of the isolation of the communities. This expands also to other areas of life and
there is often limited access to health care and education. Dry spells and predation by animals require fulltime watch of the crop (birds, rats, mammals, etc.).
In many instances shifting cultivation is mentioned as a major cause of deforestation and subsequent soil
erosion. But there is also growing appreciation on sustainability of shifting cultivation systems in areas of
relatively low population pressure, where the fallow period is sufficient to allow soil fertility restoration. There
are good examples of sustainable swidden systems from for example Laos and Western Cambodia from
areas of low population pressure. Often the critical figure is about 20 people/sq m. Above this the systems
cease to be sustainable.
In Thailand agricultural encroachment follows once logging has opened up new forest areas. These areas are
planted with both food and cash crops such as upland rice, cassava, maize, and bananas. In Vietnam there is
about 1 million people of ethnic minorities practising shifting cultivation and another 2 million in-migrant Kinh
to the mountain areas practising a mixed production system (MRC, 1997).
Upland rice production is a good indicator of shifting cultivation as it is most commonly produced in such
systems. In a simplistic way one can model shifting cultivation systems based on two parameters, human
population density and market access. Increasing population pressure pushes farmers to farming systems
that are intensified and sedentary and increased market access increases production of cash crops. In areas
of low population pressure and low market access traditional shifting cultivation is practised. In their most
traditional form these can be found in some areas in Laos and Northern Yunnan. Integrated rice-based
systems where upland rice is grown in rotation with other annual crops in fixed fields can be found in areas
with high population pressure but lack of markets. This type of areas can be found in Northern Vietnam and
Northern Laos. A rather recently emerged systems are those where annual crops are grown in association
with perennial crops such as rubber, oil palm and fruit trees. Yet another type are systems in which upland
cultivation is increasingly more dedicated to intensive production of cash crops, a good example being the
temperate vegetable production systems in Thailand. In the following the GMS countries are placed in a graph
illustrating the type of upland agriculture practised in relation to population pressure and access to markets
(Figure 1.).
It is interesting how most of the GMS countries still by and large locate in the Type 1 category of traditional
slash-and-burn. Only Thailand can be categorised to be between Type 2 and Type 4 systems, i.e. having high
population pressure combined with high access to markets. There is, however, increasing number of mixed
systems in each of the GMS countries and the change process is quite dynamic and it is likely that the type 4
and 2 categories will increase in the coming years.
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3. EXTENT OF SOIL EROSION AND CURRENT SOIL AND WATER CONSERVATION
MEASURES IN SOUTHEAST ASIA
3.1 Introduction
Accelerated deforestation, production of annual food crops by shifting cultivation, and transition from long to
short fallows or continuous cropping as well as cropping in new niches, such as steep slopes, result in soil
erosion, removal of natural vegetation and perennials from landscapes, and eventually in watershed
degradation, and loss of biodiversity. In South and Southeast Asia, about 16 % of all the land used is
seriously degraded. Estimates of the annual economic loss of the agricultural GDP due to soil degradation
range from 7 to 11 % (16). In the GMS there are high erosion rates especially in Yunnan, Central Highlands in
Vietnam and Northern Thailand on the Korat Plateau.
About 21% of the soil degradation in southern China and Southeast Asia are caused by water erosion (16).
Erosion has several disadvantages associated with the productivity of land as well as several off-site
problems such as siltation, drainage disruption, gullying of roads, euthrophication, loss of wildlife habitats,
damage to public health, plus increased water treatment costs. Of the 75 x 109 tons of soil eroded world-wide
each year, about two-thirds come from agricultural land. This loss costs the world about $ 400 billion per year,
including losses due to nutrient loss, water loss and off-site impacts (36).
3.2 Erosion rates for various land uses and terrain types:
Erosion in the Mekong River Watershed, comprising areas from Cambodia, Laos, Myanmar, Thailand,
Vietnam, and Yunnan Province of southern China, has increased tremendously mainly due to increasing
population pressure. Although Cambodia and Laos still have a major portion of their natural environment
intact, their resource base has been significantly degraded (63). In Laos, an estimate of overall soil loss in
1960s was approximately 0.3 t/ha, but has since increased severalfold (24). Myanmar, Thailand, Vietnam,
and Yunnan have lost a major portion of their forest mainly due to shifting cultivation, illegal timber
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exploitation, and natural fires. Therefore, the most urgent environmental problems are deforestation,
continued rapid soil degradation, and wasteful land use practices (63). Mountainous environment adds to the
problem; approximately 85% of the population of Yunnan lives in area in which only 6% of the land has a
slope of less than 15%. Human influence has severely influenced the sedimentation process, the estimated
sediment yield being about 5.5 t/ha/year in a lake catchment in Yunnan (61).
The major determinants of water erosion are rainfall, soil type, topography, particularly steepness and length
of slope, and plant cover (38). Annex 1 summarises soil loss (t/ha) in different upland regions in the humid
Southeast Asia and similar conditions elsewhere. Most soil loss occurs from soils with steep slopes and with
little soil surface cover. Actual losses are loosely related to the character and maturity of different agricultural
crops, i.e. the erosion risk varies during the growing season or during the lifetime of a plantation. Soil loss
from cropping systems including annual crops, particularly crops having wide row-spacing and requiring
regular weeding (cassava, maize, and vegetables) (1, 2, 8, 25), is more severe than losses from cropping
systems including perennial crops and/or trees (14, 26, 27, 48, 51). Rates of erosion under forest cover vary
with soil types but are generally low (1, 26, 27, 38), whereas rates of erosion in freshly logged over areas can
be extremely high (1). Soil loss during fallow period may be as high as 700 t/ha/year (41) (Table 1).
Choosing an appropriate land use should drastically curtail and even prevent accelerated erosion. Erosion will
not be severe if the unproductive original vegetation can be replaced with a more productive land use without
seriously altering the ecological balance that exists in an undisturbed environment (24). In choosing
appropriate land uses and soil and crop management practices the acceptable soil loss levels range from 2.5
to 12.5 t/ha/year, depending on soil characteristics (24, 59). Most tolerance estimates are, however, based
only on the productivity decline caused by erosion, without consideration of the off-site damage (24).
3.3 Soil and water conservation practices:
If the cultivation of erosion-prone land to seasonal crops cannot be avoided, then soil management
techniques that prevent direct raindrop impact on a bare soil surface should be used, i.e. techniques that help
keep water infiltration rates high enough to reduce runoff to a negligible level (cover approach). On steep
slopes, practices that permit safe disposal of runoff water from the field when rainfall exceeds the infiltration
capacity of the soil should be implemented (barrier approach). Wide adoption of good land-husbandry
practices requires replenishment of soil resources as well as increased productivity and farm income in the
short term, as farmer willingness to invest in soil improvement is closely associated with the overall economic
profitability of farming (13,16). Solving the problem involves the conservation of natural resources and the
environment as well as consideration of the country's socio-economic conditions (10). Annex 2 shows the
efficiency of several different approaches tried in curtailing erosion in the humid tropics, particularly in the
Southeast Asia. Annex 3 summarises the suitability of different conservation methods and land-use systems
on soils of different slope and the additional benefits and the major constraints associated with a particular
method.
Soil loss from erosion is nearly proportional to the exposed soil surface. Therefore, selection of crops and
combinations contributes significantly to soil conservation. Instead of monocropping, preference should be
given to cropping systems with multicanopy structure and those that provide continuous vegetative cover
throughout the year (24). Thus, proper crop management, such as vigorous seed and timely and close
planting, combined with contour cultivation as well as multiple cropping (intercropping, relay cropping and
mixed cropping), can be effective conservation measures. Success in controlling erosion varies a lot, ranging
from 0 to 80 % (2, 25) (Table 2). Contour-based cultivation, particularly when combined with grass planted in
contour strips, is considered to be effective both in terms of control and costs (49, 53). These measures are
effective only on gentle slopes, and require additional conservation measures on slopes steeper than 12-15%
(Table 3). Intercropping perennial crops with annual crops may improve erosion control compared to
intercropping annual crops (42).
Cultural practices that maintain a high infiltration rate include mulch farming, use of crop cover, and
conservation tillage systems. Crop residue mulch protects the crop against raindrop impact just as dense
vegetation cover does. The effectiveness of crop mulch, however, depends on soil properties, the
predominant slope and the ground cover. Mulching has proved to be effective in controlling erosion on wide
range of slopes (14, 20, 48, 51) (Table 2), but in general, additional conservation measures are necessary
when applied on slopes steeper than 15% (Table 3). Frequent use of cover crops in rotation is
recommended to provide ground cover quickly and protect steep slopes from accelerated soil erosion.
Fallowing with appropriate cover crops is also important in restoration of eroded and degraded lands, e.g.
improvement of soil fertility and maintenance of organic matter content (22).
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No-till cropping is an effective method in preventing soil loss (50 to 99%), depending on the slope and the
cropping system (23, 30, 31, 42, 62). Additional construction structures can improve erosion control (48), but it
is generally unnecessary to use other erosion control measures, such as terraces and diversion channels, as
long as slopes do not exceed 15 %and there is an adequate quantity of crop residue or mulch. Thus, these
benefits are to large extent attributable to the crop residue mulch. However, tillage may not necessarily
contribute much to erosion control in swidden cultivation as most slash-and-burn systems already involve lowor no-till practices (18).
Biological methods of soil conservation, such as buffer strips of grass or herbaceous vegetation may be
more effective and economical than terraces for controlling erosion and reducing runoff velocity. Placing
deep-rooted perennial shrubs at regular intervals may provide the barrier needed to decrease runoff velocity
and encourage sedimentation (24). Vegetative barriers may be easy to plant, and effective at controlling
erosion, but require a level of management input not characteristic of many slash-and-burn agroecosystems
(18).
For soil and water conservation on gentle and moderate slopes, up to 35%, hedgerow intercropping (alley
cropping), i.e. planting of hedges along the contours, with alleys usually 2-8 m wide, offers a means which is
viable, and in many respects preferable to conventional methods (5, 34, 49, 53, 59). Alley cropping has also
been accepted and adopted relatively well by farmers (49). On moderate slopes, erosion has been reduced
by 50 to 99% (3, 30), whereas on steep slopes, 35 to 70%, it is uncertain whether hedgerow systems can be
effective (37). Additional measures, such as intercropping, no-till practices, and contours, may improve
erosion control (4, 30, 23, 37).
A range of engineering techniques, including land shaping, construction of contour bunds, and diversion
channels, are recommended for safe disposal of excess runoff. The usefulness of terraces in soil and water
conservation is a controversial issue, and the effectiveness of these devices depends on soils, topography,
and management (12, 24).
Conservation bench terraces have been found effective for rice cultivation on sloping lands. Bench terraces
are generally more effective on slopes steeper than 12%. They are expensive, difficult to construct, require
considerable technical supervision, and require departure from the existing agricultural practices of
subsistence upland growers. They are prohibitively expensive in some developing countries and can occupy
as much as 35% of the cropping area on 10-12% slopes. However, in systems where land use pressure is
extremely high construction of terraces provides an effective, although labor intensive, form of soil
conservation (18).
There are several less expensive and labour intensive simple terraces available for production of different
crops. Several studies report hillside ditches to be effective in erosion control (5, 39, 53). Hillside ditches are
particularly suitable for semi-permanent upland crops up to 47% slope (12). Orchard terraces are suitable for
fruit trees, food trees or tree crops on steep slopes of 47 to 58%, whereas the main tree crops and other large
plants are preferably planted in individual basins. Usually they are applied in conjunction with agronomic
conservation measures. Convertible terraces are suitable for mixed farming or for flexible land use, from 12
to 36% slope. Intermittent terraces on slopes from 12 to 47% slope, can be used for upland crops or partly
irrigated crops, whereas natural terraces are only suitable for crops grown on gentle slopes. These
structures should be protected by planting suitable cover crops. If terraces are not properly constructed and
adequately maintained, erosion can be more severe than without them (12).
A range of engineering techniques, including land shaping, construction of contour bunds, and diversion
channels, are recommended for safe disposal of excess runoff. The usefulness of terraces in soil and water
conservation is a controversial issue, and the effectiveness of these devices depends on soils, topography,
and management (12, 24).
Conservation bench terraces have been found effective for rice cultivation on sloping lands. Bench terraces
are generally more effective on slopes steeper than 12% (Table 3).
They are expensive, difficult to construct, require considerable technical supervision, and require departure
from the existing agricultural practices of subsistence upland growers. They are prohibitively expensive in
some developing countries and can occupy as much as 35% of the cropping area on 10-12% slopes.
However, in systems where land use pressure is extremely high construction of terraces provides an effective,
although labour intensive, form of soil conservation (18).
There are several less expensive and labour intensive simple terraces available for production of different
crops. Several studies report hillside ditches to be effective in erosion control (5, 39, 53). Hillside ditches are
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particularly suitable for semi-permanent upland crops up to 47% slope (12). Orchard terraces are suitable for
fruit trees, food trees or tree crops on steep slopes of 47 to 58%, whereas the main tree crops and other large
plants are preferably planted in individual basins. Usually they are applied in conjunction with agronomic
conservation measures. Convertible terraces are suitable for mixed farming or for flexible land use, from 12
to 36% slope. Intermittent terraces on slopes from 12 to 47% slope, can be used for upland crops or partly
irrigated crops, whereas natural terraces are only suitable for crops grown on gentle slopes. These
structures should be protected by planting suitable cover crops. If terraces are not properly constructed and
adequately maintained, erosion can be more severe than without them (12).
Besides the on-site cost, erosion also has an off-site cost. The TSS loads in the Mekong average 300 mg/l,
but vary a lot from site to site. The TSS loads are higher upstream and also increase in the rainy season.
While sedimentation deposits a layer of fresh soil in the delta, which is good for soil fertility, it is very
damaging to infrastructures and aquatic ecosystems. Sedimentation disturbs hydrological regimes, fish
populations, hydropower plants and river transport. There is a study from Chiang Mai from a high erosion site,
where the off-site cost of erosion was calculated to be 1 million Bhat/ha (??). The off-site cost of erosion
should be increasingly internalised in making the cost-benefit calculations of investments in soil conservation
measures.
Table 3.1: TSS loads at selected sites along the Mekong and its tributaries
Station
TSS (t/sq km)
Mainstream
Chiang Saen
356
Vientiane
221
Nakhon Phanom
183
Pakse
249
Tributaries
Nam Mae Kok
77
Nam Kam
15
Nam Ngum
72
Nam Mun
14
Se Done
249
Source: Wilander, A., Water quality in the lower Mekong Basin
– Status and trends (University of Uppsala, undated)
In conclusion, both nutrient depletion and soil loss threaten the long term sustainability of farmers’ livelihood
(40, 56). Soil conservation techniques are less readily acceptable if they only give positive results several
years after implementation (39), thus, efficient soil conservation can be most rapidly implemented when based
on the modification of indigenous measures, rather than implementation of imported ones (55). Farmers will
select a conservation technique based on the efficiency to control erosion, the short-term benefit (yield,
fertility), and the ease in implementation (time, labor, costs). One of the few soil conservation methods
accepted by farmers has been intercropping perennial crops with annual crops (39). Similarly, alley cropping
and hillside ditches have been accepted relatively readily (39, 49). It can be concluded from the foregoing that
a range of technical options are available to improve the protective function of a watershed without sacrificing
the income of the farmer.
Useful web-sites on soil erosion:
http://www.jas.sains.my/doe/new/index.html
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http://www.giub.unibe.ch/cde/auxil/isco/earth.htm
http://soils.ecn.purdue.edu/~wepphtml/wepp/wepptut/main.html
http://www.clw.csiro.au/research/agriculture/tropics/
http://climchange.cr.usgs.cov/rio_puerco/puerco2/causes.html
http://www.uia.org/uiademo/str/j5666.htm
http://blackbox1.wittenberg.edu/academics/geol/progcrs/geol220/eric/erosion.htm
4. EXPERIENCES OF UPLAND DEVELOPMENT OPTIONS
As discussed above in detail the slope level and the general agroecology sets the physical frame of
agricultural practices. Beyond this is the sphere of interaction with the economy, i.e. markets and policies,
which create or destroy an enabling environment for change. In the centre then is the farming household with
its socio-economic and cultural interactions, which also can be either enabling or hindering forces for change.
4.1 Systems analysis-approach
In searching for alternatives to shifting cultivation one needs to examine the proposed area at different
systems levels. Firstly, the agroecological determinants are critical limiting or enabling factors (slope level,
soils, rainfall, etc.). For example, Phantanousy has suggested broad guidelines for crop production on
different slope categories: slope from 0-5 degree, good for permanent agriculture such as wet rice or cash
crops; 6-10 terracing or alley cropping systems; 11-15 agro-forestry and integrated farming systems; 21-25
protected zone. The next level is the farm-household system. Educational level, health, time and task
allocation by gender, etc. are critical factors at this system level. Further, the next level in the systems
hierarchy is the community systems and linkages to other communities, including access to markets,
production inputs, etc. Based on a systems hierarchy analysis one can search for alternatives to stabilise and
intensify agriculture on the sloping lands.
Development scenarios for uplands in Laos (Chazee,1994)
Scenario 1. Improving cropping system of the sloping land by cash crops (coffee, tea, castor…). Need to
know: the interest of the village and farmers? are soils suitable? are markets accessable? Are prices high
enough to secure good returns? Are support services available (credit, equipment, techniques)?
Scenario 2. Improved environmental sustainable of existing production systems. Need to know:
indigenous knowledge of the farmers? Opinions and long term objectives of the farmers? If the idea is to go for
terraced paddy fields, the soils should have more than 40% clay, be fertile and have possibility for irrigation. A
yield of 3tns/ha is required to compensate for the investment. If the idea is to grow annual cash crops one needs
access to markets. If the idea is to produce free-grazing animals, need to know the interests of the people,
options for pasture and forage development, permanent access by vehicles for vet services. If the village is very
isolated and no Lao language skills, hard to improve the cropping system only without parallel input into
education, access to markets, etc.
Scenario 3. Encouraging people to move from the sloping land to low land production: ensure access to
land and water, health care services, credit for vaccinated buffalo, access to technology, literacy program and
Lao language program.
5. PRESSURES AND CONSTRAINTS TO CHANGE UPLAND FARMING SYSTEMS
There are pressures exerted on upland communities to change towards sedentary and more intensified
agricultural production systems. One of the major push factors for change at the community level is increase
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in human population pressure as indicated earlier. Once the population density reaches the carrying capacity
of the area people are forced to look for alternative livelihood options, because the fallow period of the soil
has reduced such that soil fertility does to have time to be restored.
At the national policy level several sectoral policies push for change including the forestry, agriculture and
energy sectors. Moreover, the environmental policies are being strengthened in many of the GMS countries
and in many instances are very strict against extensive farming systems. Above these sectoral policies is the
overall influence of economic policies towards increased liberalisation, seeking of regional comparative
advantages and thus integrating the upland communities more to the mainstream economy.
As the pressures become too constraining the communities change their livelihood systems by intensifying
crop production, shifting to cash crops or livestock or by seeking wage labour. This change is likelier to
happen spontaneously the closer the community is to the mainstream economy and the alternatives it can
offer. However, many of the remote watersheds live in absolute poverty, where the main concern is to secure
food for the family for the entire year. These communities have very limited investment potential to change
their production system or ability to absorb the risk of trying something different. Thus, they remain locked into
their existing livelihood system, which as such can be the best option with their existing resource base.
Therefore, if change is desired there needs to be an increase in the resource base to remove the senior
constraints to change. These resources can include financial, technical know-how and production inputs, but
often also require input into road infrastructures, health and education, especially language training. Based on
the discussion with many resource persons from the GMS countries it became quite clear that the more
remote the upland community is the more horizontal and integrated the development approach needs to be.
In short,
Mid-elevation communities benefit from pull-factors in the liberalising economy and the process can be
facilitated by external assistance
Remote communities in critical watersheds need horizontal development assistance - health, education,
agriculture, infrastructure, women’s empowerment training, etc. before encapacitated to benefit from
economic growth
6. ICRAF AND ALTERNATIVES TO SLASH AND BURN
ICRAF (International Centre for Research on Agroforestry) is the lead agency for a CGIAR-systemwide
program on Alternatives to Slash and Burn (ASB). The program is global. Thailand is presently a participant
from SEA and Laos and Vietnam are being considered to be included. The ICRAF team led by Dr. David
Thomas located in Chiang Mai University has done a lot of excellent analytical work on shifting cultivation
systems and related socio-economic and cultural issues. In northern Thailand the forces driving the change
from slash and burn include population increase, migration, roads, opium, market integration and
environmental concerns. The team has selected a bench-mark site, the Mae Chum watershed (not in the
GMB) to study the impact of these factors. The foundation of the project is to recognise local variation and to
identify ‘best bet’ solutions, which vary from site to site.
In the following is a list of parameters suggested by ICRAF to assess the suitability of a new production
practice:
1. Land pressure (land-labour ratio, competition, conflict, land tenure)
2. Natural resource base characteristics (inherent potential, current condition)
3. Access and mobility (roads, markets, inputs, capital-credit; local knowledge, information, education
4. Commercialisation (desire for, current degree and past success)
5. Local organisation and institutions (control of fire, grazing and protected areas; landscape
management systems)
6. Content, enforcement and perceptions of government policy, laws and regulations (tenure, land-use
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restrictions, infrastructure, services)
In the following graph adopted from ICRAF ASB program the above questions are illustrated in a highland
situation in Thailand for the three upland zones.
Large graph here.
Source: ICRAF, 1998.
The analytical framework and tools developed in the ASB program are very useful in assessing the
development options of a watershed and the investments required. The program has also come up with
valuable insights into highland development. One is that the development process is iterative. The initial
spatial information system should be built on continuously as feasibility and other field studies proceed. The
interlinkages between household, community, region and nation have to be constantly mirrored. A change in
the policy environment can impact development of the other levels as well.
7. CONCLUSIONS
Poverty is widespread in the mountainous areas of the GMS. Especially the remote communities live in
hardship with little potential to change their livelihood systems. Communities closer to the regional towns can
better benefit from the economic alternatives available, and often spontaneously respond to internal pressures
to secure livelihood for their families. The agroecological framework to a large extent governs the choices of
agricultural production systems. In the foothills and lower slopes there are quite a few alternatives to explore
for crop diversification. In the mountains agroforestry systems are increasingly expanding. From the sectoral
development point of view export oriented agriculture can benefit uplands greatly as many of the export crops
are grown in these areas. Environmental degradation, especially soil erosion caused by deforestation,
infrastructural development and shifting cultivation is proceeding at an alarming rate in some areas in the
GMS (Yunnan, Korat Plateau, Central Highlands). A range of technical soil conservation methods are
available for different slopes and climates. The most appropriate for a particular community should be chosen
and adapted together with the farmers. Community participation is essential for sustainable development and
creation of ownership and commitment, and maybe most importantly to support the processes of
democratisation and decentralisation. Experience is available for watershed management from the GMS and
this should be fully utilised when developing the Phase II investment plan.
Annex 1:Soil loss (t/ha) in the humid tropics in different cropping systems without specific soil and
water conservation measures.
Slope (%)a
Soil loss (t/ha)
Location & reference
Rice
wide range
8-15
Thailand (42), Java (52)
Rice
30-45, 54
0.3-30, 52
Laos (40), Thailand (15)
Cassava
< 1-5, 10-15
3-87, 125-221
Nigeria (2)
Cassava
13-44
120
Vietnam (25)
Vegetables
up to 50
20-200
Malaysia (8, 1)
Maize
11
28
Nigeria (29)
Maize
up to 50
14.2-76
Philippines (30, 37)
Cropping system
Annual crops
Perennial crops
Page 11 of 18
Rozelle fiber crop
3.6-5
2.8-5
Thailand (48, 64)
Tea plantation
Unknown (uk)
6.7
Malaysia (26, 27)
Cocoa +/- banana
18
17 - 104
Malaysia (14)
Banana, Citrus
28
92, 156
Taiwan (46)
Undist. Rainforest
gentle
1.9-7.5
Malaysia (1)
Forested land
15-20
0.2-0.4
Malaysia (26,27),Thailand (38)
Selective logging
steep
112-285
Malaysia (1)
Natural/legume
10
0.006-1.0/9.0
Malaysia (28)
Weedy field
20
1.4
Thailand (38)
3.6
48
Thailand (47)
10-18
11.2-181
Malaysia (28,14)
up to 28
300-700, 557
Rwanda (41, 14)
30-40, uk
31.3-71, 10-233
Thailand (52, 48, 6)
50
137
Philippines (37)
Forest
Fallow (with cover)
Bare fallowb
a Slopes can be divided to following categories; gentle = 0-12 %, moderately sloping = 12-27 %, strongly
sloping = 27-36 %, very strongly sloping = 36-47 %, steep = 47-58 %, and very steep = > 58 % (12).
b Bare fallow is difficult to maintain in the tropics, and as such, is an unnatural situation.
Annex 2. Effect of soil and water conservation measures on soil loss and erosion control success in
the humid tropics.
Method
Primary crop
Slope %
Soil loss
(t/ha)
Control
%
Location &
Reference
Annuals
Cassava + maize
<1-5, 1015
3-50, 86137
0-43,
31-38
Nigeria (2)
Annuals
Cassava+legumes
13-44
20 - 26
79-83
Vietnam (25)
Maize
1-15
0.05-0.2
~ 99
Nigeria (20)
Intercropping
Mulching/cover crops
Mulch (6 t/ha)
Page 12 of 18
Mulch
Cocoa +/- banana
18
1.6-5
91-95
Malaysia (14)
Grass/ferns
Rubber
7-10
44/ ~ 0
57/100
Malaysia (51)
Grass
None
40
2.1
97
Thailand (48)
No-till
Annual crops
Unknown
(uk), 3.6,
7
0.00260.8
89-99
Thailand (42),
Philip-pines (30),
Nigeria (23)
Minimum tillage
Rice
uk, 30
1.0, 24
92, 5075
Thailand (42, 62,
31)
Min.tillage+construction
Rice
30
12
76-88
Thailand (48)
Contours
Rozelle (fiber)
3.6
1-1.5
64-46
Thailand (47)
Contour furrows/bunds
uk
20-30
0.43-8.4
69-73
Thailand (38, 52)
Hedgecropping
Annual crops
15-20,
45-75
< 1, 1337
98, 5157
Peru (3),
Colombia (60),
Philippines (37)
Hedges 2/4 m + no-till
Maize
uk
0.07-0.17
99
Philippines (30)
Hedgerow + intercrop
Annual crops
7-20
0.95-5.8
89-93
Nigeria (23), Peru
(4)
Hedgerow + intercrop +
contours
Maize,
potato
50
5.4
93
Philippines (37)
65-41,
63
Rwanda (41, 19)
95-89,
> 96
Rwanda (41, 19)
Minimum tillage
Contour cultivation
Alley cropping
sweet
Agroforestry
Agroforestry
Annual crops
uk, 28
30-50,
111
Agroforestry + hedges
Annual crops
uk, 28
1-16,
12.5
Groundnut,
54
6-8
88-85
Thailand (15)
~ 30
1-12.5
69-93
Java (52),
Thailand (52),
Nigeria (21),
Sierra-Leone
(32), Malaysia
(51)
30
11.7
63
Thailand (52)
<
Structural measures
Terraces
Rice and
annuals
Hillside ditch
uk
other
Annex 3: Conservation measures and land-use systems and their adaptability in different conditions
Page 13 of 18
Method
Slope
Preconditions/Supplemental
conservation measures
%
Additional things to consider
Agronomic practices1
Multiple cropping2
* + conservation structures
(CS) on steep slopes
* higher total yield/land unit, risk
reduction
£ 12
* requires permeable soils
* may be difficult to build/maintain
steep
* + CS on steep slopes
* cost-effective on gentle to moderate
slopes, but costly on steep slopes
£ 15
* + CS on steep slopes
* o.m. supplement, green manure
£ 1215
steep
Contour cultivation &
close planting
Mulching & cover
cropping
steep
* annual replenishment, cost of mulch
* poor performance on steep slopes
Minimum tillage
£ 15
* + simple structures on
steep slopes
* 50 persondays (PD)/a vs 80 in
traditional cultiv.
steep
* root crops difficult, lower yields
occasionally,
* may require herbicide use
Strip cropping +
vegetative barriers
£ 12
* + CS on steep slopes
* labor input limited, management
input high
steep
* moderately effective
Land-use system
Hedgecropping
£ 18
* + CS on steep slopes
* cutting & pruning necessary, 125-150
MD/a
£ 35
* potential competition with crop
* occupies 10-15 % of land area
Agroforestry3
£ 6070
Pasture4
£ 47
Forest
any
* dense planting of trees
necessary on very steep
slopes
* labor input high, waiting cost
* + CS on steep slopes
* management of grazing intensity
* land security, market dependency
* takes long time to reach maturity
Conservation structures5
Bench terraces
12-47
* requires relatively deep
soils
* effective, but occupy up to 35 % of
land
* can be used in
* labor intensive: 500-1650 MD/ha
Page 14 of 18
combination with cover
crops, hedge cropping
(slope size)
* expensive
Simple terraces6
wide
range
* planting of cover crops for
support
* cost ~1/5 of bench terraces
* labor requirement 80-150 MD/ha
1 Agronomic practices are always recommended to be used, on gentle slopes alone and on steep slopes in
combination with conservation structures.
2 Multiple cropping includes intercropping, relay cropping, and mixed cropping.
3 Agroforestry includes trees on cropland, multistorey tree gardens, plantation crop combinations, and
reclamation forestry, excluding hedgecropping.
4 Pastures should be used on all soils which are shallow, stony, wet, or flooded, regardless of slope.
5 Waterways, gully control structures, diversion channels, drop structures, check dams, and submerged dykes
are essential supplemental components of conservation structures (FAO Soils Bulletin 60).
6 Simple terraces include hillside ditches, individual basins, and orchard, convertible, intermittent, and natural
terraces.
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