SUSTAINING NATIONAL WATER SUPPLIES BY UNDERSTANDING THE
DYNAMIC CAPACITY THAT HUMUS HAS TO INCREASE
SOIL WATER-HOLDING CAPACITY
by
Glenn David Morris
This dissertation is completed in a holistic style which reflects the wider knowledge base
required for sustainable studies, and is submitted in partial fulfillment of the requirements
for the degree of Master of Sustainable Agriculture.
Faculty of Rural Management
The University of Sydney
July 2004
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ABSTRACT
Despite volumes of technical advice from mainstream scientific disciplines and continued
alteration of natural environments, conventional systems of land management have been
unable to maintain or improve the sustainability of natural land and water resources.
Hydrological system breakdown as a result of land degradation is now threatening to
severely impact upon agricultural as well as city water supplies.
This study has identified a possible solution to the problem of increasing water shortages
by investigating the natural ecological processes which are responsible for creating robust
water systems in nature, and suggesting that it is now time to redesign the management
systems of an industrialized era which have failed to maintain soil and water resources.
A thorough review of literature to quantify the water-holding ability of humus indicates a
biological solution is possible to the growing water crisis in Australia. The initial
discussion describes the negative cycle of depletion created by falling humus levels,
reduced water-holding ability and continuing land degradation in Australia. The main
body of work discusses the complex nature of soil humus and the processes necessary to
build soil humus levels, as well as an investigation as to a reliable guide for estimating
the water-holding capacity of soils containing varying levels of soil humus at a catchment
scale. Finally a number of farming systems are discussed which provide methods of
increasing soil humus as well as ensuring that new systems of land management are
designed to be truly sustainable.
The multi-faceted benefits of soil humus ensure that any well designed program to
increase soil humus to improve hydrological functions would be equally beneficial in
areas such as farm productivity and the abatement of greenhouse gases.
A major finding of this study was that the subject of soil humus is critically under studied
and thoroughly underestimated as a component of land and water management systems.
It was found that the water-holding ability and nutrient status of soils can be dramatically
improved by the development of land management systems which enhance the creative
processes of soil biology and the naturalised agro-ecosystem.
Co-incidentally, the improvement in soil humus levels leads to soil structural
improvement and increased plant density and ground cover, greatly alleviating the
damaging factors which cause land degradation and water system breakdown.
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The quantitative results of this extensive review were to find that one part of soil humus
was able to store approximately four parts of water, demonstrating significant potential
gains in soil water storage capacity at a catchment level.
Finally it was concluded that national water supplies can not only be sustained, but more
importantly enhanced through the adoption of a better understanding of land management
practices which enhance a dynamic state of soil humus development in Australian soils.
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DECLARATION
I certify that this dissertation does not incorporate, without acknowledgement, any
material previously submitted for a degree or diploma in any university. It does not
contain any material previously published or written by any other person except where
due reference is made in the text.
This dissertation does not exceed 15,000 words.
Signed
Glenn David Morris
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ACKNOWLEDGEMENTS
I would like to acknowledge the following people:
My dear wife, Katrina Grace for her loving patience and support.
My three wonderful young boys for their understanding.
William Clinton for financial backing.
Adam Wilson for inspiring hope in a difficult world.
Andrew Rawson - Dissertation Supervisor.
Christopher Morgan – Unit Coordinator
Dedication
Dedicated to my father in heaven, his grandchildren on earth and
all the future generations that walk on this magnificent planet.
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PREFACE
In the present times of economic prosperity and globalization, the environment which
supports us has been largely neglected. Warnings about climatic chaos and increasing
natural disasters have constantly been restricted from the public by governments lacking
the vision or will to implement change. Revolutions are brought about by realising a real
need for total change; the community must now be brought to understand, that we have
now entered the most important turning point in the history of the earth. The time has
come to move on from the complacency of an outdated industrialized civilization and
develop a brighter more intelligent vision for the future and all future generations.
The very survival of the most unique planet in the universe is now dependant on a new
revolution. A revolution which seeks to understand and enhance the biological processes
of natural eco-systems. Loyalty to a resource degrading and polluting industrialized
system either for personal wealth or political opportunism is a very high price to pay for
destroying a planet, a planet which belongs to the children of the future.
This study reveals that by adopting a natural approach to resource management that we
can not only limit further environmental degradation, but we can in fact enhance
ecosystem functioning to a higher level of performance. Water supplies can be enhanced
at a national level only when we endeavor to understand the integrated processes which
exist between the soil water storage system, plant processes and the atmosphere.
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Table of Contents
Chapter 1 Introduction – Ecosystem Regeneration
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Chapter 2 Background on Environmental Issues
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Chapter 3 Quantifying the Water Holding Capacity of Humus and Soils
Containing Humus: Part A
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Chapter 4 Formation of the Humus Colloid
4.1 Biological Processes
4.2 The Organic-Inorganic Synergy
4.3 Chemical Bonds in Humus Formation
4.4 Physical Processes of Humus Formation
4.5 The Physical Makeup of Humus
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Chapter 5 Developing a hypothetical model to be used as a basis for quantifying
the water-holding capacity of humus and soils containing humus: Part B
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5.1 The Humus/Water-Holding Capacity Ratio
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5.2 Water-Holding Capacity Increase for One Hectare for Varying Levels of
Humus Increase
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Chapter 6 Farming Systems Designed for Increasing Soil Humus,
Water-Holding Capacity & True Sustainability
6.1 Sustainable Farming Systems
6.2 Aims of Organic Agriculture
6.3 Biological Farming Objectives
6.4 Principle Aims of Bio-Dynamic Agriculture
6.5 Holistic Management Model
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Chapter 7 Humus Building Methods in Natural Farming Systems
7.1 Mineral Balancing For Building Humus
7.2 The Soil Foodweb and Humus
7.3 Mechanical Methods for Improving Humus Levels
7.4 Green Manures
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Chapter 8 Co- Incident Benefits of Organic Carbon Sequestration
8.1 Reducing Carbon Dioxide Levels in the Atmosphere
8.2 Cooling Land Temperatures, Reducing Fire Risk and Creating Local Rainfall
8.3 Humus and Human Health
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Chapter 9 Conclusion - The Sustainable Revolution
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References
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Chapter 1 Introduction - Ecosystem Regeneration
Fresh water, fertile soils and clean air are the natural foundations of life and form the
basis of a safe, peaceful and prosperous society. It is the responsibility of every society
that these basic elements are passed on to future generations in abundance, just as they
were passed onto past and present generations. This study recognizes that present
management of these vital resources has lead to a state of deterioration and that they will
continue to decline further unless urgent steps are taken to address the foundation causes
of their demise.
Recent periods of extreme drought and the associated depletion of water supplies in
Australia have highlighted a critical dependence on natural systems and brought about
much discussion on water management. Of primary concern has been the debate over the
allocation and use of reduced water supplies. This report aims to change the focus of
acceptance of natural resource decline to one of opportunity. An opportunity to
commence an unprecedented era of natural soil improvement, and water system
enhancement.
The present generation has the knowledge and ability to commence an unprecedented era
of restoration, regeneration and aquafication, where land and water resources are secured
for all future generations. Salatin (1995, p.50) writes, “It is important to remember that
every single desert in the world is man-made. And in fact the deserts will green up again
when proper grazing occurs. The Greek historian Homer, author of the Iliad and the
Odyssey, walked across the entire North of Africa, what is now known as the Sahara, and
said he never left the shade of a tree”. Desertified areas in India are presently being
reclaimed by restoring water courses and regenerating localised hydrological systems
(Suzuki & Dressel 2002), demonstrating that with the application of natural land
management principles man can re-aquify the landscape.
Using a holistic, inter-disciplinary and simplified approach this study investigates a
potential solution to some of Australia’s most threatening resource challenges. A natural
solution, which combines two of the earth’s major global material cycles, the carbon
cycle and the hydrological cycle.
By enhancing natural processes through sustainable management systems the energy
from the earth’s largest energy source (173,000 terawatts), the sun, can be utilized to
sequester carbon from the atmosphere and returned to the soil as organic carbon.
Through enhancement of biological activity the soil would then regain its capacity to
build soil humus, store moisture and act as a catalyst for renewed hydrological activity.
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The important atmospheric and hydrological services provided by the environment would
then be recognised by the community, and an appropriate government support program
for carbon sequestration initiatives could be designed. The proposed initiative will call
for greater understanding, enhancement and management of natural ecological processes.
Due to environmental pressure and an increasing rate of natural disasters other countries
are already adopting an inter-disciplinary and holistic approach to resource management
and it is rapidly becoming the foundation for sustainability around the world. In the
European Union a new directive known as the Water Framework Directive (WFD) has
been implemented with the desired outcomes of “good ecological status of surface waters
and a good quantitative and qualitative status of groundwater by the year 2015” (Mostert
2003).
The primary aims of the EU WFD are:
1) mitigation of the effects of floods and droughts
2) develop a good quantitative status for ground water
3) designation of water storage, regulation, flood protection and drainage as
heavily modified systems
4) incorporate quantity issues with economic aspects of the WFD
In the United States soil conservation efforts have undergone a major change of direction
from managing for tolerable levels of land degradation (factor T) to a perspective of soil
enhancement through building soil organic matter and soil carbon (factor C), with the
primary objective of enhancing productivity and environmental quality (NRCS 2003).
This study attempts to quantify the potential capacity of soils to store additional water for
given increases in soil organic carbon and humus, identifying that the importance of this
relationship is vital to understanding the essential role that humus performs in
maintaining a functioning hydrological cycle. In order to achieve a truly sustainable
society a new paradigm in land and water resource management is required. This
paradigm will leave behind a reductionism scientific approach, and realise the vital
importance to view land and water resources in their entirety. Society needs to accept
that the health of the land and water resources we depend on is created by complex
interactions between living organisms, inorganic minerals and the waste materials of
plants, animals and microorganisms.
Suzuki and Dressel (2002, p.68) state that under a growing revolution in sustainability,
“mainstream science and economics do not reflect the latest findings of physics: that
relationships between components are the key to understanding their functions, and that
the whole is a great deal more than the sum of its parts”. This statement helps explain the
need for a new way of thinking, if rivers are to be restored or if salinity is to be slowed,
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how can water losses be reduced from the landscape. An understanding of soil processes
is a vital necessity in developing sustainable systems for land and water resource
management.
Albrecht (1975) suggested that there was confusion over natural functions and biology in
agriculture, he stated that, “agriculture is biology first and foremost and technology and
management second”. The confusion and inability to define biological and organic soil
properties by conventional sciences has lead to a situation whereby their vital importance
has been overlooked. Albrecht (1975) “let us try to comprehend the fact then that soil
fertility coupled with plant nutrition is a form of creation, a form of outdoor biology, and
not a matter merely of scientific technology”. This reference to creation is very important
when discussing the formation of soil humus, a process whereby the discarded wastes of
plants and animals are transformed by biological processes into a storehouse of nutrition,
air and water for new life.
This study aims to demonstrate the importance of building soil humus levels in order to
maintain a robust hydrological system. Precise chemical formulations, mathematical
equations and rigid definitions will not occupy the content of this paper. Soil humus for
the purposes of this paper will be valued for all its complexity, entirety and its colloidal
water retention properties. After reviewing the pertinent literature on the relationship
between humus and water–holding capacity a model will be developed to serve as a guide
in calculating the additional water holding capacity of soils at a catchment, state or
national level.
Methods for regenerating stable humus levels in catchment soils will be discussed,
including a range of sustainable farming systems which have been developed to
encourage the accumulative soil building processes of natural biological systems.
While this study primarily deals with the water-holding capacity of humus, there are
many other possible benefits to the agro-ecosystem and environment that can be achieved
through the sequestration of organic carbon. Reducing green-house gas concentrations in
the atmosphere is one key benefit which will be discussed. This benefit and other
co-incident benefits of carbon sequestration will be briefly covered to demonstrate the
inter-connected benefits of developing an ecological approach to water resource
management. Other benefits which will be covered include areas such as, more
permanent river flows, higher natural soil fertility with more nutritional food products,
protection of estuaries and marine systems, reduced soil temperatures and impact on
bushfire severity. Financial incentives should be based on the higher quality of produce
and its health properties and the clean air and water provided by a healthy environment.
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Chapter 2 Background on Environmental Issues
Land and water resources in Australia can be improved to a healthy status when the
foundation cause of land and water degradation is acknowledged. In order to restore
water supplies an understanding of why water losses have occurred is necessary. By
identifying the cycle of declining humus, reduced water holding capacity and increasing
land and water degradation, programs can be developed to reverse the cycle. While it is
well understood that many forms of land degradation have had a devastating effect on the
Australian landscape it is less commonly realised that the foundation cause of many of
these problems is common to all. The loss of water holding ability in Australian soils has
initiated a devastating cycle of terrestrial and marine degradation ranging from the visible
effects of soil erosion to the slower and more insidious effects of dryland salinity, acidity
and marine sedimentation.
The Australian Agricultural Assessment (2001) estimates that about 127 million tonnes of
sediment enters Australian rivers from hillslopes, gullies, and riverbanks each year with
about 70,000 tonnes of phosphorous attached to the sediment. Yencken and Wilkinson
(2001, p.266) state, “the unsustainability of current agricultural systems relates to the fact
that, unlike natural systems, they are unable to use all of the water that falls over a year
and so they leak much more water, nutrients and salt than the natural systems they
replaced”. The inability of Australian soils to retain water has been created by a modern
era of agricultural science and land management which has largely neglected the integral
relationship between soil humus and water retention.
Jones (2001, p.2 ) comments that the experience given by European explorers was that,
“soils were variously described as mulched, peaty, soft, loose, friable and high in humus,
even in relatively low rainfall areas”. Soils of this description would be in such a state
that it would not only absorb large quantities of rainfall but would also retain this
moisture for gradual release over time. Gale and Haworth (2004) found that following
European settlement soil loss increased by a factor of 50 for 25 years. Soil loss increased
from 25 t kmˉ²a to 1360 t kmˉ² a. The study also found that prior to European contact
many Australian soils appear to have been composed of uncompacted material of low
bulk density and relatively high infiltration capacity.
A well structured porous condition of the soil would act as a regulating system against the
extremes of flooding and the rainless periods of drought. It would also act as a measuring
system for providing basal flows to perennial watercourses over long timeframes
Mollison (1992) states, “free (interstitial) water can as take as long as 1–40 years to
percolate through to streams. Greatly alleviating droughts, it also recharges the retention
storages along the way”. Eventually the water would filter through the soil profile to
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replenish the extensive ground water systems which are currently being pumped faster
than they are being recharged (Yencken and Wilkinson, 2000).
The continual loss of water–holding ability in Australian soils has been brought about by
a constant decline in soil humus levels and an associated deterioration of soil structure.
There are many factors which have all contributed to the decline of humus levels in
Australian soils. Primarily land clearing, constant grazing pressure and extensive soil
tillage have all contributed to humus depletion. The removal of organic material through
grazing, farming or fire, combined with the destruction of the microbial environment in
the soil, has effectively reduced any significant level of humus production.
The combined effects of soil compaction, loss of vegetation and reduced water retention
effectively destroy the ecosystem required for microbial processes and humus production.
A continual cycle of erosion pre-cursers developed, including:
1) further loss of soil structure, porosity and microbiological habitat;
2) loss of fertility with further reductions in organic matter production; and
3) a further reduction in soil water-holding capacity.
The list of land and water degradation issues connected with the decline of soil humus
levels and associated reduction in soil water–holding capacity is extensive. The
Australian Agriculture Assessment (2001) noted the following land degradation issues as
being linked to changes in the hydrological cycle.
1) Nutrient Loss caused by:
 Changes to biogeochemical cycles and components of the hydrological cycle
 Soil erosion by wind and water
 Nutrient exports in harvested farm products
2) Organic Matter Loss caused by:
 Change to total biomass production and biomass return to the soil; chemical
transformations following soil disturbance
 Wind and Water erosion of top soil
3) Salinization caused by:
 Changes in components of the hydrological cycle, particularly a decrease in the
volume of water lost through inception and evapotranspiration and an increase in
deep drainage of soil water, where there is a high salt storage in the catchment
regolith or groundwater
 Alteration to vegetation, particularly perenniality, leaf area index, and root depth
 Practices which affect soil structure and downward movement of water through
the soil
4) Soil Loss caused by:
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
Changes in the balances and transfer of energy in the system and in components
of the hydrological cycle
 Wind and Water Erosion
5) Waterlogging caused by:
 Primarily changes in components of the hydrological cycle, particularly a
decrease in the volume of water lost through inception and evapotranspiration;
waterlogging can also result from a decrease in soil permeability of subsoil layers
(plough pans) river quality, eutrophication, low volumes
6) Soil Acidification caused by:
 Changes in biogeochemical cycles of carbon and nitrogen (increased nitrogen
input and loss of nutrients in produce) and in the hydrological cycle (increased
leaching of nitrate and soil cations)
7) Soil Structure Decline caused by:
 Depleted soil organic matter
 Excessive or inappropriate tillage
 Soil compaction by machinery or livestock
 Poor soil drainage
 Exposure of hard setting topsoil by overgrazing or soil erosion
There are many other forms of land and water degradation such as the destruction of coral
reefs which can be added to this list which identify the loss of water-holding capacity in
soils as the primary cause. Increasing the water-holding capacity of soil is therefore
fundamental in addressing land and water degradation and ultimately ensuring the
continued functioning of hydrological systems.
Chapter 3 Quantifying the Water Holding Capacity of Humus and Soils Containing
Humus: Part A
The positive relationship which exists between soil organic matter and water-holding
capacity is one which most scientists, horticulturalists and agriculturalists acknowledge as
being important. Occasionally though there is reference made by those with an
understanding of natural soil processes to the actual level of moisture retained by humus.
Due to the implications of water–holding capacity to land degradation and also water
supplies this relationship between water and humus is of national importance. Wheeler
and Ward (1998, p.16), state, “humus is the primary reason why soil is able to hold
water”. They make reference to soil humus holding four times its weight in water.
Podolinski (1985) stressing the colloidal properties of humus estimated that humus is
capable of holding 75% of its volume in water, adding that the water will neither
evaporate or leach out. Podolinsky (1985, p.21) cautioned about losing sight of the
wholeness of this product, adding “that no matter what can be analyzed and measured and
argued and hypothesized about, humus as a whole is a colloid”. Before continuing to
quantify the water-holding capacity of humus it is necessary to understand the formation
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and physical properties of the humus colloid. A better understanding of its impact on
soil processes and water-holding capacity can then be gained.
Chapter 4 Formation of the Humus Colloid
4.1 Biological Processes
In order for organic matter and root exudates to be transformed into humus the soil must
be able to provide suitable conditions for microorganisms to exist. Soils which already
contain good levels of humus will display good porosity, levels of oxygen and water and
will enhance the production of new humus. Soils which have been subject to humus
depletion, as a result of compaction, mineral depletion and the overuse of synthetic
chemicals will restrict the number and performance of microorganisms and slow the rate
of soil improvement. Stable humus formation in the soil begins with the interactive
breakdown of plant and animal remains carried out by a diversity of soil fungi, algae,
bacteria, actinomycetes earthworms, macro fauna, meso fauna and micro fauna. The
compounds remaining from microbial activity consuming plant root exudates also act as
an important source of humus material.
The concept of plants building soil humus through micro-organism activity is
fundamental in understanding how we can increase water storage in the landscape. “Such
a strong symbiotic relationship exists between plants and soil that it could be argued that
the plant exists to build soil rather than the soil being used to grow plants” (Wheeler and
Ward, 1998). This re-conceptualisation of the way we view the roles of plants and soil
processes is critically important in changing the way we manage natural resources.
Handreck (1938) found that, “root cells exude all manner of organic chemicals, aminoacids, sugars, organic acids and gelatinous materials which are immediately pounced
upon by multitudes of bacteria”. Up to 30 - 40 percent of foods produced by the plant
may be transferred into the soil as root exudates or broken off cells. Analysis of humus
by Handreck (1938) concluded that, “humus was really a polyglot collection of very
large and complex molecules……formed from lignin and other poly-phenolic molecules
of the original plant leaf and in part from similar molecules which have been produced
by microbes [feeding on root exudates and organic matter].” A major point of relevance
here is that plant root exudates are a significant source of carbon to be processed by
micro-organisms into the formation of soil humus, significantly contributing to aggregate
stability, soil fertility and water storage capacity.
Given that plants have also been found to be able to condense up to 20 percent of their
water requirements from the atmosphere (Went, 1955) and even transfer some of this
moisture back to the root zone, the humus zone in the rhizosphere would act as a ‘major
reserve system’ for both moisture and nutrients, available for later use by the plant.
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Schroder and Hartman (2003) found that, “the structure and abundance of microbial
populations are dependant both on the plant and soil type”. A further understanding of
the processes of soil humus formation would then suggest that the degree of
mineralisation and production of poly-phenols in the plant would inevitably flow through
to the quality of soil humus which is formed, ultimately influencing water storage and
stable eco-system functioning.
Recent studies into the effects of plant breeding and the use of chemical pesticides,
herbicides and fertilisers on plant nutrient density have shown a deleterious effect on
poly-phenolic compounds in plant material. This hypothesis would concede that the
restoration of water systems and soil fertility based on the formation of adequate humus
levels is then dependant on a change to new management systems which use plant species
and cultural practices that maintain plant nutrient density.
Lines-Kelly (2005) refers to the University of California findings, that suggest that,
“pesticides and herbicides may actually reduce the production of poly-phenolics by
plants”. Anderson (2000) suggested that modern agriculture, in a very simplistic
approach, had identified only a small fraction of the important compounds in plants
essential for plant and human health, intensive analysis of the secondary metabolites and
phenolic compounds in several plant species revealed a huge variation in phenolic
compounds between traditional varieties and modern varieties.
Further analysis of phenolic compounds when plants were treated with recommended
levels of nitrogen fertiliser, revealed that following treatment phenolic compounds
virtually disappeared. The link here is that if we are to maximise the synergy between
plants, soil microbes and humus to provide our own needs in the way of water and
nutrition, we must ensure that practices that we conceive as being innovative are not in
fact resulting in the breakdown of important biological processes.
Conventional agriculture has resulted in separating plant processes with active soil
formation by overlooking the importance of living ecological systems. We must now
adopt an important lesson from plants, that if we are to continue receiving a bountiful
supply of goods and services from the soil, we must learn how to return something back
to nature in the way of careful stewardship and life-promoting inputs which enhance not
destroy biological processes.
4.2 The Organic-Inorganic Synergy
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The ability of soils to build water-holding capacity is related to their potential to store and
protect the organic carbon (humus) from complete microbial breakdown. This protection
is aided by various chemical and physical bonds with the inorganic soil fraction.
Waksman (1936, p.v) after fifteen years of studying the origin and chemical nature of
humus identified that, “unjustified comparisons between the natural humus compounds,
formed in soils, composts, or bogs, with artificial preparations produced in the laboratory
by the action of strong mineral acids on carbohydrates, served not to advance the subject
of humus, but rather to confuse it….. The study of physical and physiochemical
properties of humus isolated from soil or from peat cannot be interpreted in terms of soil
processes, without proper modification”. This confusion over the formation and
properties of humus has continued until the present day primarily because of a
concentration of study into the varying chemical fractions of humus and a lack of study
into the effects of stable humus in field conditions where the biological, physical and
chemical complexes have occurred. Sometimes the importance of soil humus has been
discounted as less important for soil properties, including water holding ability, than that
of soil texture (Hayman 2003), although it is the interaction of the inorganic materials
with humus which ultimately provides for a stable and healthy soil condition. Waksman
(1936, p.310) states, “the colloidal constitutes of the soil – the inorganic clay fraction and
the organic or humus fraction do not operate independently of each other, but give mixed
or compound colloids”. It is these compounds which are now found to be responsible for
giving the soil its positive physical, chemical and biological characteristics (Tan 2003).
Of particular importance in the context of soil water retention is the effect of the stable
humus colloid on soil structure, stability and water storage capacity. Gedroiz (1929, cited
in Waksman 1936, p.314) stated, “the organic colloids in the soil exert an aggregating
effect on the inorganic colloidal particles of the soil, favoring the formation in the soil of
micro-structural units, which possess a marked resistance against the disaggregating
action of adsorbed monovalent cations; the removal of the colloidal humus part of the soil
increases the dispersing action of these cations”.
4.3 Chemical Bonds in Humus Formation
Tan (2003) attributes the formation of favorable soil structure to the interaction between
humic acids and inorganic clays. Tan (2003, p.254) states, “the effect of humic acid is to
create and preserve a stable structure that can provide the proper amount of pore spaces
for the storage of optimum amounts of water and oxygen”. The formation of the humic
matter/clay colloid is achieved by a process of bridging, whereby the negatively charged
humus colloid is bonded to the negatively charged clay colloid, either with a positively
charged H atom in a water bridge, or via metal bridging with an Al or Ca cation (Tan
2003). The formation of this stable humic matter/clay colloid may then lead to the ideal
soil conditions for biological performance, water storage capacity and environmental
stability.
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Tan (2003) attributes the high water-holding capacity of some soils to a combination of
the adsorption capacity of humus combined with the abundant macro- and micro pore
spaces created in the crumb structures, resulting from good humus and clay reactions.
The structure and water holding ability of sandy soils was also found to be enhanced
through the cementing action of humic acids. Although the humus content of the soil is
often very low (below 3%) compared with the inorganic component of the soil matrix it is
the ability of humus to act as a catalyst for improved soil structure and water-holding
ability which is of vital importance. Ehrenberg (1924, cited in Waksman 1936, p.308)
observed that “the humus sol first peptizes the aggregated clay particles; this is followed
by the formation of a layer of absorbed humus sol around the clay fractions; as a result of
this, the latter require much higher concentrations of electrolytes for flocculation, since
they behave as if they were made up entirely of humus”.
This influence over the entire soil matrix may be explained due to the ability of the
spongy extracellular material (humus gel) to coat the inner surfaces of the inorganic soil
pores. The development of a porous coating upon the micro and macropores creates an
exponential increase in the number of sites for water absorption and storage. Waksman
(1936,p.308) stated that , “in a soil with favorable texture, one finds good drainage and
aeration, while too much leaching and evaporation are prevented; this is due to the fact
that the clay particles are coagulated and the sand particles cemented together through the
action of the humus”. Waksman (1936) attributed a favorable soil texture to the influence
which humus has over the inorganic fractions of the soil. Given that soil textural classes
are determined on there permeability and fracturing levels in a moist condition humus
would hold significant influence if present.
Humus through its effects on the inorganic soil fraction could therefore reduce water
percolation rates through the soil as well as preventing the surface runoff of water. This
function would aid greatly in reducing salinity, erosion, sedimentation, etc. The soil
would then function naturally as a significant land/ water reservoir.
Alway and Neller (1919, cited in Waksman 1936), who carried out detailed studies on the
relationship between soil humus and water-holding capacity found that, “an increase in
the humus content of the soil is accompanied by an increase in the moisture holding
capacity, probably due largely to the inhibition of water by the humus gel”.
Mollison (1992) also noted the immense potential that soils had for water storage, he
listed several systems for water storage in the soil.
 Retention storage: as a film of water bound to the soil particles, held by surface
tension
 Interstitial storage: as water filled cavities between soil particles
 Humus storage: as swollen mycorrhizal and spongy detritus in the humic content
of the soil.
Mollison (1992) noted the fact that soils of fine texture containing high levels of organic
matter could hold significantly higher volumes of water as retention storage alone, before
the effects of interstitial water and humus storage were taken into account. The capacity
of mycorrhizal fungi to store water also demonstrates the need for a far greater
understanding of biological processes in the soil.
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4.4 Physical Processes of Humus Formation
Kay (1997) describes the formation of stable humus in the soil as a physical process by
which humus material and inorganic matter interact; protecting the organic carbon from
further microbial attack and in the process, sequestering organic carbon. Through the
process of humification humus material impregnates the internal surfaces of pores in the
soil matrix as well as adsorbing to the exterior of mineral particles, to give a positive
affect to both soil structure and water-holding capacity.
Kay (1997, p.174) explains, “Part of the microbial biomass may grow into pores adjacent
to the plant residue or may be squeezed into this space along with the extracellular
material if the water absorbed by the growing population of organisms and increasing
quantities of extracellular polysaccharides exceeds the pore space where the particulate
carbon is located”. Forster (1998, cited in Kay 1997) found dense mucilage may
impregnate the soil fabric as much as 50 μm from the plant residue. Kay (1997) through
the work of Golchin et al. (1994) found that the organic material closely associated with
the inorganic fraction of the soil would appear in the >2.0 gm cmˉ³ density fraction and
had a composition which suggested it was mainly of microbial origin. Kay (1997)
suggested that this humus material would, “exhibit water release characteristics that were
much different from those of soil materials”. Research by Chenu (1993, cited in Kay
1997) enforced the influence of the extracellular polysaccharides over water release
characteristics on sand and clay by showing that, “the addition of scleroglucan increased
the available water by about 26g water per g adsorbed organic carbon irrespective of
whether the addition was to sand or Ca-montmorillonite”. Kay (1997) then explains how
the polysaccharides are physically protected from attack by microorganisms and
extracellular enzymes.
Steric considerations related to the size of bacteria (e.g., Bakken and Olsen,
1987; Forster, 1988) and the relation between the size of the bacteria and the size
of the pore neck that they can pass through (e.g., Kilbertus, 1980) suggest that
few, if any, bacteria would penetrate pores with necks smaller than 0.2 μm. The
rate of mineralization of polysaccharides located in pores smaller than 0.2 μm
would then be controlled by the diffuse flux of extracellular enzymes into these
pores. The concentration gradient and, therefore, the diffuse flux would decline
with increasing distance between the bacteria and the polysaccharides and
therefore polysaccharides located in these pores would be provided a measure of
protection against mineralization. The volume fraction of pores < 0.2μm is
strongly positively-correlated with clay content and, therefore, the proportion of
carbon existing as polysaccharides closely associated with the mineral phase
should be expected to increase as clay content increases.
17
A matrix of plant residues, microbial biomass, and extracellular material that
becomes encrusted by mineral matter dominated by small pores may become the
center of water stable aggregates.
Kay (1997) has described here an important physical process by which a stable humus
colloid is formed and the means by which soils can build humus levels and store
increased amounts of water. This physical process would help explain the increased
exposure and lack of protection of soil humus in sandy soils and the need to manage for
continued humus production.
Although there is still some debate over the importance of the physical or chemical
processes in the formation and functions of humus, there is a common theme of
realization as to the important role that humus has in enhancing soil structure and waterholding ability. It is this important role that must now be understood to hold the secret
for sustaining Australia’s water supplies.
Waksman (1936) had an early insight as to the important role that soil humus should play
in sustainable land management, he states, “the amount of water and of nutrient salts
adsorbed by the colloidal humus system is of great agricultural significance, since it is in
this system that the major microbiological activities take place; it is in this system and not
in the free soil solution which is of greatest importance in the study of the availability of
various nutrient elements for the growth of higher plants”.
Humus through its unique ability to store nutrients and water should be considered to be a
major component in maintaining hydrological regimes in the soil as well as in
watercourses and in the atmosphere, through the soils effect on continued plant growth
and evapotranspiration rates.
4.5 The Physical Makeup of Humus
The physical descriptions of soil humus are quite varied due to the fact that the
composition of humus is very complex, existing in a state somewhere between a liquid
and solid form. More precisely humus is described as an amorphous material, that is, a
material lacking definite form and having no specific shape. Waksman (1936) described
humus as a, “hydrophile colloid”. Other descriptions include extracellular material,
plasma, and porous gel like substance and so on. The physical makeup of humus appears
to contribute significantly to its ability to penetrate and hold influence over the entire soil
matrix.
18
Electron microscope investigations of humus have identified a loose spongy structure
ideally suited to holding water and air. (Khan 1971). Schnitzer and Kodama (1975, cited
in Stevenson, 1994) examined the structure of fulvic acid in highly acidic soil conditions
to find:
1) A sponge-like polymeric structure perforated by voids or holes of relatively large
dimensions;
2) The occurrence in the polymeric structure, apparently in free form, of very small
spheroids 20 to 30 Å in diameter and aggregates of spheroids; and
3) A structure sensitive to small changes in pH, aggregating when the pH is lowered
and dispersing when the pH is raised.
The above structural description serves to demonstrate one example of the physical make
up of the humus fractions, their porous characteristics and their ability to absorb and
retain water.
Kay (1997) provides a description of a micro aggregate consisting of remnant plant cells
encrusted in mineral material and showing cellular remnants bonded with inorganic
material. Electron micrograph images (Waters and Oades 1991). Figure 1 graphically
illustrates the inner porosity of a micro-aggregate of stable humus.
Figure 1: Remnant porous structure of a stable humus aggregate (page 20)
19
20
Chapter 5 Developing a hypothetical model to be used as a basis for quantifying the
water-holding capacity of humus and soils containing humus
In order to establish a hypothetical model to be used as a platform for further
investigation and discussion the calculations for water-holding capacity will be
constructed more as a conceptual guide than an accurate account. As much as possible
figures used will be based on studies which have been conducted from soils derived from
stable field conditions. The dynamic state of change as well as variability in soils,
topography, climate, vegetation, soil biology and humus compounds would in any case
make accuracy of figures fanciful.
This study therefore aims not to define the precise results of a scientific study but rather
to understand a complex interaction between the humus soil system and the hydrological
processes within the soil. Waksman (1936, p.7) highlighted a need for understanding the
natural processes of the soil system, “humus is not in a static, but rather in a dynamic,
condition, since it is constantly formed from plant and animal residues and it is
continually decomposed further by microorganisms”. Given that the stability of land and
water resources are dependant on the functions of soil humus and humus is constantly
being utilized and transformed it would be logical to ensure that the provision of material
and conditions for ongoing humus production is maintained. The present era of industrial
agriculture and forestry has failed to account for the resource security of future
generations by ignoring this fundamental element of agricultural and environmental
cycling.
When estimating the potential increase in water- holding capacity for a soil with varying
quantities of humus there are two sets of figures which have commonly been cited in
literature.
1) The ability of humus to hold 20 times its weight in water
2) The ability of humus to hold 4 times its weight in water
Reports by Stevenson (1994), recorded that organic matter could hold up to 20 times its
weight in water, but no reference was made to humus in field conditions. This figure
compared with studies of peat by Waksman (1936) whereby 9-25 parts of water were
necessary to saturate one part of peat. Once again the figures did not refer to humus
under a stabilized humus/cation/clay colloid structure and therefore not a reliable guide
for water retention changes at a catchment level.
Tan (2003, p.257) noted that, “the humo-Ca-clay mineral chelates are considered the
reason for the preservation of soil organic matter (humic acids) and for the development
of granular structures and other favorable physical characteristics in mollisols”. In
andosols it was the bridging interaction of humo-Al allophone or humo-Si-imogolite
complexes or chelates which are responsible for the favorable physical soil properties.
Tan (2003, p.256) suggested “the accumulation of organic matter (humic acids) known
21
for its high adsorption capacity for water, together with the increased amounts of pore
spaces, therefore increases the water holding capacity of the andosols”.
Kay (1997) correlated the formation of stable humus and increase in water-holding ability
to the physical protection given by micropores in the range of <0.2μm.
In order to improve the water–holding capacity (WHC) of soils in the agro-ecosystem it
is important to gauge this potential on realistic assumptions of improvements in the WHC
as a result of increased stable humus complexes in field conditions. Quantitative studies
which have looked at increased WHC as a result of increased humus levels are scarce.
In 1915 a field study was conducted at the Ohio Experiment station to study the waterholding capacity of a silt loam soil. The study was conducted to question the assumption
that, “increased amounts of organic matter in the soil resulting from applications of
manure caused an important and beneficial increase in the water supply of crop plants, it
both enabling the water to be absorbed more readily during heavy rains and increasing
the amount held against downward movement, thus retaining a more generous supply
within reach of crop plants” (Alway and Neller, 1919). The site of the study was
considered excellent due to the uniformity of soil texture and well established history.
The land had been cleared of forest in 1856 and was treated alike for the following 36
years (1856-1892). In 1893 some plots were kept in 4 and 5 year rotations including
clover and manure, while the others were devoted to continuous cropping with no
fertilizer or manure. In 1915 all plots were prepared alike and planted with the same
crop. Tests were conducted 15 times over 4 months on the top foot of soil between two
plots which had a 1.37% variation in organic matter. The results indicated a 5%
improvement in water-holding capacity for a 1.37 % increase in soil organic matter.
The researchers concluded that, “the difference in moisture content are as great as would
be computed on the assumption that the organic matter of this silt loam has the same
water holding capacity as some of the most absorbent peat’s, some of these, even when
well drained, being able to retain 300 to 400 parts of water for every 100 parts of dry
peat” (Alway and Neller 1919).
The results from this field study were comparative with figures established by Wheeler
and Ward (1998) for humus holding four times its weight in water in field conditions.
Waksman (1936) conscious of the diversity of humus pointed out that the capacity for
humus to hold water is dependant on a range of factors leading up to testing, including
the material from which it originated, degree of decomposition, reaction of the soil and
environmental conditions. Wollny (1897, cited in Waksman 1936) stated, “the greater
the extent of decomposition of humus, the greater the increase in volume of soil on
moistening and decrease upon drying; this is due to the specific colloidal properties of
humus”. This reference concerns the humus formed after microbial decomposition rather
than partly decomposed organic matter.
22
Extensive field research by Waksman (1936) found that 100 parts of humus in mineral
soil was capable of holding 400–600 parts of water. Golchin et al. (1994, cited in Kay
1997) used spectroscopic analysis to find that the portion of organic carbon material
(humus) closely associated with inorganic materials was relatively uniform irrespective
of the composition of the original carbon source. Kay (1997) suggested that the organic
carbon (humus) after being processed by microorganisms was uniform, irrespective of
soil properties or the nature of the carbon entering the soil system. This finding would
allow broader guidelines to be used in relating soil organic carbon (humus) levels back to
water retention levels for different soils.
Kay (1997) estimated that, “an increase in the organic carbon content of 1g per 100g soil
would lead to an increase in available water of 2.6 to 6.5g water per g organic carbon”.
This figure was derived by considering that 10 to 25 % of the carbon in soil is
polysaccharide material, closely associated with the mineral phase (Golchin et al., 1994
cited in Kay 1997) and multiplying by the factor of 26g increased water per g adsorbed
extracellular polysaccharide (calculated by Chenu 1993). Kay (1997) therefore based the
increased water-holding capacity of soil on the effects of the extracellular material
(polysaccharides) in connection with the mineral fraction of the soil, or the function of
the stable humus colloid.
Golchin et al. (1994, cited in Kay 1997) added further important observations, regarding
the rate of decomposition of different organic fractions in relation to water-holding
capacity. Golchin et al. (1994) found that, during the decomposition of the stable humus
aggregate, the more labile portions of the core (proteins and carbohydrates) are consumed
and the more resistant plant materials, (which have low O-alkyl, high alkyl, and aromic
content) are concentrated as occluded particles within the aggregates. The remaining
material was more hydrophobic and less strong bonding with the mineral fraction of the
soil. Stable humus fractions in the soil therefore act in a manner, similar to the materials
from which they were derived. The lignin derived fractions of humus helping form the
framework and porosity of soil structure, while the carbohydrates and proteins provide
the essential elements for the growth of biomass.
This study suggests that the extracellular (humus gel) material in the soil, sometimes
referred to as active humus is largely responsible for water retention. It also shows that
microorganisms are constantly breaking down the humus which is essential for a resilient
soil structure and fully functioning hydrological cycle, backing up the view held by
Waksman (1936) that humus exists in a dynamic state, constantly being formed and
continuously being broken down. Additionally this study finds that the fractions of
stable humus responsible for the greatest degree of water retention are the first to be
decomposed suggesting that if the hydrological functions of catchment soils are to be
restored and maintained there is a need for greatly increased turnover of organic matter
23
into active humus. This study also shows that the lignin derived fractions of stable
humus play a critical role in complexing with clay and metal ions to increase the
stabilized structure and porosity of the soil.
Australia’s soils, rivers, water supplies and marine environments are therefore dependant
on the development of land management systems which lead to an improvement in the
dynamic state of soil humus.
5.1 The Humus/Water-Holding Capacity Ratio
By combining modern testing procedures with the results of extensive field research, a
guideline has been established for the relationship between soil humus and water-holding
capacity.
The combination of spectroscopic analysis, electron micrographs and water release
characteristics used by Kay (1997), produced an organic carbon (humus) to water-holding
capacity ratio of 1: 2.6 to 6.5, corresponding with the estimated humus : water ratio
established by Waksman (1936) 1 part humus held 4 to 6 parts water, and
field trials by Always and Neller (1919) 1 part humus held 4 parts water and
Wheeler and Ward (1998) 1 part humus held 4 parts water (Based on USDA figures)
For the purpose of developing a broad scale and practical model for estimating increases
in water-holding capacity for given increases in humus at a catchment level it is
suggested that a 1% increase in soil humus will result in a 4% increase in stored soil
water. Also for the purposes of a hypothetical model and practical implementation an
average figure of 4,000,000kg will be used in calculations for a 30cm deep soil profile
over 1 ha. Realistic target increases in soil organic carbon (humus) could be given for set
areas of land use and soil characteristics or alternatively an average organic carbon
increase could be set for catchments based on the variation of soil types and topography
within a catchment. The use of figures is purely to demonstrate the potential
improvement in water retention and the potential volumes of water saved from escaping
catchment areas.
24
5.2 Water-Holding Capacity Increase for One Hectare for Varying Levels of Humus
Increase
Using the guideline ratio, which has been established for additional water retention the
following gains can be expected.
Humus Increase
0.5%
1%
2%
3%
4%
5%
Increased Volume of Water Retained /ha (30 cm)
(OC% x 4,000,000kg x 4)
80,000 litres
( average 2004 level)
160,000 litres
320,000 litres
480,000 litres
640,000 litres
800,000 litres
(pre-settlement level)
The Clarence Valley catchment has an area of 2,300,000 ha; a 0.5% increase in humus
(organic carbon) would therefore store an additional 184,000,000,000 litres of water
following an adequate rainfall event.
Given that a 25mm rainfall event over one hectare of land would deliver approximately
250 000 litres of water. Soils containing 1% humus would be able to consume less than
half of the water in such an event. This would lead the soil conditions which rapidly
become over saturated, pre-disposing the catchment to soil erosion. Alternatively the soil
conditions associated with low humus levels may result in the soil being unable to absorb
the large volumes of water in heavy rainfall, leading to surface losses of water from the
catchment system and ultimately negative impacts on soil resources and downstream
water systems (Wheeler and Ward 1998).
In broad terms soils would therefore need to contain approximately 2½ % humus in the
top 30cm in order to retain the volume of water delivered in just 25mm of rain. At the
upper end of the scale, Mollison (1992) noted that soils of fine texture and high organic
matter content were capable of storing 100 to 300mm of rain in the top 30cm of the soil
profile. The volume of water contained in 300mm of rain would equate to 3,000,000
litres of water stored over one hectare.
A 100mm rainfall event over the entire Clarence Catchment would deliver 2,300,000
megalitres of water to Clarence Valley soils. With each additional increase of 1% humus
over the valley, an additional 368,000 megalitres of rain would be stored in the soil water
storage system, gradually recharging ground water systems and percolating through to
water courses to provide perennial water flows, even in times of low rainfall. Average
pre-settlement organic carbon levels have been estimated at being in excess of 5%
25
compared with organic carbon levels now, which are found to be at less than 1%. Over
an area the size of New South Wales (80,142,800 ha) that would equate to a drop in
water-holding capacity of 51,291,392 megalitres following an adequate rainfall event
(fractionally more than 50mm of rain).
In a river catchment basin such as the River Murray (1,057,000 square kilometers) a 2%
increase in humus would equate to an increase in water-holding capacity of 33,824,000
megalitres of water. This water would be withheld from deep drainage and rapid surface
runoff which cause, raised water tables and other forms of land and water degradation.
The increase in transpiration from additional plant growth would then become the
catalyst for localized hydrological effects which would be again held in the effective soil
horizon of plant roots creating a positive cycle of increased plant growth, humus
formation, transpiration and rainfall.
As mentioned previously, this paper does not strive to give an accurate account of water
volumes, but has tried to use a meaningful model to demonstrate the important role which
humus (organic carbon) has to play in restoring hydrological functions in catchment
areas.
It is therefore in the soil’s water-storage capacity that the greatest hope lays for reducing
land and water degradation issues and ensuring sustainable cycling of agricultural and
natural resources, including water. The primary objective of land management beyond
2004 must now focus on developing holistic land management systems which have the
capacity to improve the constant formation, quantity and cycling of soil HUMUS.
Chapter 6 Farming Systems Designed for Increasing Soil Humus & Water-Holding
Capacity & True Sustainability
Conventional land management practices in Australia have created soil conditions which
restrict the process of humification and add to further depletion of existing soil organic
carbon. New land management systems must be designed which aim to increase the
degree of organic matter cycling in the soil. By increasing the rate of organic matter
turnover and managing soils to create the optimum conditions for biological activity,
microorganisms will proliferate and increase their production of humus. With continued
corrective management a positive cycle of further increases in biological conditions,
humus production and agro-ecosystem sustainability will occur. Zimmer (2000) notes
that beneficial organisms in the soil require the following conditions and materials in
order to function:
 well-aerated soil (good structure),
 a moderate amount of moisture, ( not to wet or dry)
 moderate temperatures,
 a source of food (organic material), and
26

freedom from harmful soil conditions (toxic substances, strong salts,
wrong pH)
The focus on creating the ideal conditions for humus production has lead to the
development of a number of natural farming and grazing systems. These land
management systems have not only recognized a need for adopting new systems of land
management, but have also recognised the need to be a part of a new paradigm in
sustainability.
Creating True Sustainability
McDonough (2000, cited in Suzuki & Dressel 2000, p.62) describes the change of
paradigms or movement into sustainability as the beginning of a second industrial
revolution, “the first was about resource extraction and money, and the second about
resource conservation and values”. He states, “A design assignment for the first
industrial revolution would have read as follows,
please design a system that pollutes the soil, air and water; that measures
productivity by how few people are working; that measures prosperity by
how much natural capital you can dig up, bury, burn or otherwise
destroy; that measures progress by the number of smokestacks you have;
that requires thousands of complex regulations to keep people from killing
themselves to quickly; that destroys biodiversity and cultural diversity;
and that produces things that are that highly toxic they require thousands
of generations maintaining constant vigil, while living in terror.
This description of the first industrial revolution could very well describe the manner in
which soil humus (described as the “product and source of life”, Hartikainen (2003)) has
been depleted with no serious questions raised to the long term implications. The failure
of the first industrial era to acknowledge the biological and environmental side effects of
industrial agriculture has created a huge legacy to future generations. The prospect of a
warming planet and global water shortages are real outcomes of previous short-term
economic policies. Modern planning for sustainability must take into account all long
term effects of present day actions.
The improvement of the hydrological cycle, as has been discussed is dependant on the
microbial humification of organic material in the soil. Short term land management
systems which increase plant growth and save water through the use of synthetic
herbicides and harmful fertilizers do not create the safe biological conditions necessary
for a dynamic cycle of humus production, the medium to long term affects will continue
to degrade soil and water resources and continue to cause a loss of water supplies.
27
Williams (1991) writes, “Agriculture must avoid the solving of one problem by the
creation of another. The crucial role of agricultural chemicals in conservation tillage
requires that the fate and long term consequences of these chemicals be fully researched
and understood…..A sustainable system is not one that finally collapses in its own
poisons or transfers them to the adjacent ecosystem”. A sustainable soil for food and
water production should not be one that is not safe for children to play in, or one that
deprives future generations of the basic essentials of life. A movement in farming
systems to improve the cycling, and building of humus must be matched by improved
biological and technological methods to suppress weeds and pests without the use of
toxic poisons.
This new era of natural soil improvement and water enhancement must be achieved as a
part of a wider society commitment to genuine sustainability. As a guideline, systems for
increasing soil humus should be measured against an international standard designed for
determining true sustainability, a system such as “The Natural Step” (TNS) which was
initiated out of concern for increasing rates of cancer in children.
TNS – Four Systems Conditions for Determining Sustainability
In order for a society to be sustainable, natures functions and diversity are not
systematically;
1) subject to increasing concentrations of substances extracted from the
earth’s crust
2) subject to increasing concentrations of substances produced by society
3) impoverished by physical displacement, over harvesting or other forms of
ecosystem manipulation
4) In a sustainable society, resources are used fairly and efficiently in order to
meet basic human needs globally.
(Suzuki & Dressel, 2000)
The Natural Step implies that in order for a society to be sustainable there is an absolute
necessity for land and water managers to have an ethical long term concern for humanity
and the environment.
28
6.1 Sustainable Farming Systems
Examples of sustainable agricultural systems of land management which are being
developed in Australia to address the need for building and increasing soil humus cycling
include: organic farming and biological farming; biodynamics; permaculture and holistic
management systems.
While these systems differ in their approaches, their fundamental aim of improving the
health status of soil through biological cycles is acknowledged as the basis for a
sustainable agro-ecological society.
6.2 Aims of Organic Agriculture
(source: NASAA Standards for Organic Agriculture, 2002)
1) To produce sufficient quantities of food of high nutritional value
2) To work positively within natural systems in ways which enhance those systems
3) To maintain and increase long term productivity of soil
4) To promote wise use of land, water and vegetation and minimize off farm effects of agriculture
on water and terrestrial systems
5) To reuse renewable resources as much as possible
6) To optimize opportunities to work within closed energy and nutrient systems
7) To provide animals with conditions which satisfy there behavioral needs
8) To increase the genetic diversity of domesticated and native plants, animals and other
organisms on the farm
9) To allow everyone involved in organic production a quality of life conforming to the UN
Human Rights Charter, to cover there basic needs and obtain adequate return and satisfaction
from there work, including a safe working environment
10) To progress towards an organic production chain, which is both socially just and ecologically
responsible
29
6.3 Biological Farming Objectives
(Source; Zimmer 2000)
- To work with the systems of nature to develop a farm which is environmentally sound and
which leaves the land, water, plants and animals in a healthy, productive state for all future
generations.
- Understand that the soil is living – alive with many organisms and balanced minerals.
To maintain good soil conditions…..
1) Always be aware of soil structure, humus and beneficial soil life and their importance.
2) Avoid practices that can destroy good soil structure:
a. Tillage when soil is to wet.
b. Unnecessary tillage.
c. Tillage tools that can compact soil or cause a hardpan
d. Unnecessary field traffic or driving on a wet soil.
e. Use of fertilizers that can destroy humus or harm soil life, such as high rates of
ammonia, dry urea, DAP (diammonium phosphate), or high salt fertilizers (potassium
chloride, or muriate of potash)
f. Use of pesticides that can kill beneficial soil microbes and/or earthworms.
3) Keep a relatively high proportion of calcium and sulphur in the soil. These elements
improve soil structure and stimulate beneficial soil life. Correct any imbalance of soil elements.
4) Frequently recycle organic matter. Add a small to moderate amount of fresh organic
material and work it into the upper layers of the soil, add compost, or grow crops with fine root
systems (especially grasses). This feeds humus producing organisms as well as directly
improving soil structure. The element sulphur is necessary to build humus and organic matter
supplies some sulphur.
5) Manage nitrogen applications. Use only as much as is absolutely necessary. Place it where
and where it is needed. Excess nitrogen reduces soil biological activity and interferes with
carbon-nitrogen ratios. The excess nitrogen “burns” or uses up the carbon to get back in balance,
burning up organic matter and humus.
6) If soil has a chronic compaction or hardpan problem, use deep tillage to break up and
aerate the soil. This should allow soil organisms to proliferate. With organic matter they should
eventually build up humus and reduce the compaction.
7) Reduce erosion:
a) Do not farm steep hillsides
b) Plant crops along the contour
c) Keep the soil covered. Grow ground covers and grassed waterways, and interplanted
row crops in row crops.
d) Build soil humus levels.
e) Promote soil life, especially earthworms.
8) Provide an abundant supply of soil minerals in the proper balance.
9) Make sure water soaks in where it falls.
10) Make sure water is stored and maintained until plants need it. Build high humus levels.
30
6.4 Principle Aims of Bio-Dynamic Agriculture
(NASAA Standards for Bio-Dynamic Agriculture)
1) Production of food of the highest nutritional value containing vital life force and the higher
ordering principles of the cosmos.
2) The enhancement of biological cycles in farming systems
3) Maintaining an increasing depth and fertility of soils
4) Working as far as practicable within a closed system
5) Co-existence with, and the protection of, the environment
6) Development of a healthy and balanced cultural, social and economic environment
7) Development of associative business forms, whereby a fair and equitable relationship is
fostered between the producer, distributor and the customer.
8) A deepening understanding of the relationship between humanity and nature
6.5 Holistic Management Model
(source; Alan Savory Center for Holistic Management, 2001)
Statement of Purpose
Whole Under
Management
Decision
Makers
Resource
Base
Money
Holistic
Goal
Quality of
Life
Forms of
Production
Future resource
Base
Ecosystem
Processes
Community
Dynamics
Tools for
Managing
Ecosystem
Water
Cycle
Human Technology Rest Fire Grazing
Creativity
Testing
Cause &
Guidelines Effect
Mineral
Cycle
Energy
Flow
Animal
Living Money &
Impact Organisms Labor
Weak Link
Marginal Gross Energy/ Sustainability Society
- social
Reaction Profit Money
& Culture
- Biological
Analysis Source
- Financial
& Use
Management Learning Organisation Marketing Time Stock Density Cropping Burning
Population
Guidelines &
&
&
Practice Leadership
Herd effect
Planning
Procedures
Feedback
Loop
Financial
Planning
Plan
Monitor
Land
Planning
Control
Grazing
Planning
Replan
Plan
31
Savory (2003) states, “The grazing planning aspect of the concept of holistic management
has its roots in his observations of the natural grazing patterns of wildlife herds in the
rangelands of Africa, where grasses were subjected to regular cycles of intensive grazing
and long periods of rest”. By mimicking the processes of natural systems, specific
grazing regimes are restoring landscapes which were previously degraded by grazing
systems which ignored natural regeneration processes.
The main difference between certified organic systems, bio-dynamic systems and other
systems in the building of soil humus is to the degree and type of inputs which may be
applied. While biological farming will permit lower rates or less- harmful products as
sprays or fertilizer, organic standards will only permit the use of natural, non-synthetic or
non-toxic products. Biological farming is often used at a stage of conversion from
chemical dependant conventional farming systems to fully organic systems which have
had time to build up humus and a natural resistance to pests. Bio-dynamic farming may
be described as an alternative where a greater understanding of cosmic energies and
forces helps the land manager achieve further improvements to soil structure and humus
development.
The building of soil humus is therefore achieved by a gradual development of soil
conditions applied in accordance with the developing managerial skills of the land
manager. In grazing systems the fundamental principles of building humus levels
continue to apply, but different methods of management are required. The underlining
principle of increasing the cycling of organic matter and groundcover is achieved through
extended periods of pasture growth combined with periods of disturbance and is carried
out by strategic grazing systems.
Whether in farming systems or grazing systems the building up and maintaining of soil
humus levels is dependant on harnessing as much natural energy as possible. Any
practices which reduce the harnessing of organic matter should be viewed as a loss of
potential energy from the system. The widespread practice of burning in rangelands
leads to a loss of organic matter, surface litter and soil biological activity. The associated
declining soil humus level eventually leads to a reduced rate of water infiltration and
water-holding capacity. The conditions necessary for productive plant growth and moist
soils are destroyed by regular burning which has then further enhanced drier conditions
favoring hot fire events and an increasing cycle of soil degradation (Jones 2002).
32
Jones (2002, p.8) states, “given the loss of the regenerative effects of small native animals
in Australia since European settlement, managed grazing is arguably the only natural
means by which grasslands can be improved in a holistic way”. Mahon (2003) found that
while strategic grazing systems could lead to an improvement in pastures, soil fertility
and soil structure, inappropriate burning, grazing and cultivation techniques would lead to
rapid depletion of soil fertility, soil structure collapse and the creation of barren depleted
landscapes.
Heavy stocking rates under continuous grazing have continually been shown to be
detrimental to water cycles in catchment areas, leading to reduced infiltration and
accelerated erosion (Warren, Blackburn and Taylor, 1986). Comparisons of different
grazing systems carried out by Lodge, Murphy and Harden (2003), found that
continuously grazed treatments were associated with low mean levels of microbial and
labile carbon and the highest amount of water lost as surface runoff compared with
rotational or fertilized sites. While fertilized sites (C8 +sub) had a higher production of
wool and liveweight gain than the site which was grazed for 4 weeks and rested for 12
weeks (R4/12), the rotationally grazed R4/12 sites had the highest total dry matter per
hectare and highest litter matter. The R4/12 also recorded a higher level of microbial
carbon and higher soil water content than other sites for the surface 30cm, which resulted
in a higher sustainability index for soil health. Holistic grazing systems are designed to
mimic natural patterns of grazing, foraging and soil disturbance which were once an
important part of the natural soil building and plant production cycle.
Chapter 7 Humus Building Methods in Natural Farming Systems
7.1 Mineral Balancing For Building Humus
A fundamental difference between sustainable farming systems and conventional systems
is the methods in which plant growth is enhanced through soil minerals. Chemical
fertilizers which rely on soluble minerals have succeeded in increasing plant growth but
have neglected the impact to soil biology, humus and regional water supplies. Mineral
imbalances created by a concentrated focus on select minerals have not only lead to
mineral deficient food but have also destroyed the physical soil characteristics necessary
for continuing plant growth and humus production. The use of artificial nitrogen is
known to deplete both carbon and calcium levels in the soil, both of which are required to
maintain a well structured and biologically active soil (Zimmer 2000).
33
Excess use of potassium or magnesium fertilizers can also displace calcium and lead to
soil compaction. The need to replace calcium may not be apparent if soil pH tests are the
only test used to determine how much calcium is required. This is due to the fact that
magnesium, potassium and sodium are all capable of raising soil pH even when calcium
is deficient. The imbalance in soil minerals and reduced porosity limits the processes of
microorganisms and stops the formation of humus. Water is no longer able to be stored
in the soil increasing the risks of drought and land and water degradation (Wheeler &
Ward 1998).
Natural farming systems have identified the unsustainable effects of using synthetic
chemical fertilizers in conventional agriculture. Plant growth and production in
biological systems are enhanced through dynamic programs which aim to increase soil
mineral levels through restricted use of natural mineral inputs and a focus of increased
humification of organic matter. By balancing natural soil minerals in the correct ratios
not only is plant growth increased but so to is the level of humus in the soil, and
ultimately the quantity of water retained in the soil and the catchment.
The nutrient storage capacity of a soil is referred to as the soils Cation Exchange
Capacity. The positively charged cations of calcium, magnesium, potassium, sodium,
aluminium and hydrogen are exchanged in the soil on the negatively charged humus and
clay colloids. Balancing a soil requires that the base saturation percentages of cations are
at appropriate levels. The ability to maintain humus levels requires a thorough
understanding of the interaction between all soil elements. Calcium has been described
as the single most important mineral needed for plant, soil and animal nutrition by weight
and by volume (Wheeler and Ward 1998), but an oversupply of calcium in the soil can
also be detrimental. Waksman (1936) found that a limited amount of calcium created a
positive influence upon plant growth whereby humus levels were maintained, yet a higher
concentration of calcium could lead to increased decomposition of soil humus.
The base saturation levels given for favorable soil conditions, dynamic humus cycling
and plant growth and high water- holding capacity are:






Calcium
70 - 80%
Magnesium 12 - 18%
Potassium 3 - 5%
Sodium
< 2%
Aluminium < 5%
Hydrogen
< 5%
34
The maintenance of soil mineral balance is an essential component of the sustainable
cycle of humus production. By providing the elements and structural conditions for
increased microorganism activity the soil increases in fertility, water-holding capacity
and organic matter production.
Due to the interconnected processes which exist between a balanced soil, soil biology and
plant growth and the production of soil humus and the functioning of regional
hydrological effects, every effort should be made to limit any negative inputs.
The excessive use of nitrogen is one input which can impact soil water processes in a
number of ways, firstly the excess nitrogen leads to a massive increase in microorganism
numbers which rapidly consume valuable soil humus, particularly as described earlier the
active humus fraction. Secondly the excess nitrogen is highly leachable and as it leaches
can often associate with calcium creating an imbalance in soil nutrients. Thirdly excess
magnesium created by the removal of calcium can combine with nitrogen to form a
magnesium nitrate salt which reduces the effect of the nitrogen. An increased rate of
nitrogen is then required to achieve the same rate of plant growth (Sait 1998). The cycle
of humus depletion is repeated until the soil totally collapses and hydrological processes
cease.
The explanation given of, a one in one hundred year drought can often accompany land
and water system degradation when soil humus has been neglected.
Natural farming systems strive to enhance plant growth without the negative
environmental consequences. The aim is to provide a balance of all plant required
nutrients through the soil humus system which is supported with judicious supply of
natural minerals. The humus colloid has been shown to have a Base Exchange capacity
over 8 times greater than the mineral fraction of the soil accounting for more than half of
the entire Base Exchange capacity of a soil complex (Gedroiz 1933, Turner 1932 cited in
Waksman 1936). The cation exchange capacity of humus is estimated at 250
milliequivalents (ME) in comparison with clay which has a CEC of approximately 40.
The stable manner in which soil nutrients can be held by humus is due to the specific
compounds which are formed in the decomposition process. Wedkind and Garre (1928,
cited in Waksman 1936) determined that lignin was capable of adsorbing ammonia and
other bases in an irreversible bond. Zimmer (2003) describes a two stage process in
which the cycle of humus production and decomposition continually provides plants with
nutrients while building soil humus levels.
The microbial breakdown of humus and other organic wastes yield ammonia and
other microbial indigestible compounds. When ammonia reacts with water it
forms the ammonium ion (NH4-) and the hydroxyl ion (OH-). Hydroxyl dissolves
humus and frees the complex acids it contains. These in turn help release
chemically bound phosphates and carbonates. Microbes that use inorganic
carbon then convert ammonium, sulphur, phosphates and carbonates into plant
available forms if the balance of other minerals is adequate. This process causes
a rapid increase in the population of these microbes and as they complete there
35
life cycles they and the indigestible “humins” (lignin fraction) contribute to an
increased supply of humus.
By balancing the soil with the correct levels of non-harmful minerals both microorganism
and plant processes can be optimized leading to a positive increase in soil humus levels
and progress of the dynamic state of humus cycling. Lovel (2004) states, “soil biology is
the nutrient sink that holds, enhances and releases the nutrients of the soil to the growing
crops……While chemical processes work with water and solubility, biological processes
hold within cell membranes and organic structures much that would otherwise be lost to
water. Tragically, soluble nutrients tend to concentrate again many miles or hundreds of
miles away – and in many cases they overburden and poison rivers, lakes, watertables
and oceans”.
The application of soluble nutrients not only allows for the pollution of water systems
and loss of soil minerals but of equally significant importance, is the loss of the soils
natural water-holding ability and the loss of billions of litres of water from terrestrial
water systems.
Economic decisions concerning the correction of mineral balance of a soil complex are
usually based on the value of the commodity being produced. Due to the significant
influence that soil humus has in maintaining a sound ecosystem, and the substantial role it
plays in maintaining fresh water supplies there is a need for wider community support
programs to assist land managers to start building soil humus levels.
7.2 The Soil Foodweb and Humus
The functions of soil fauna and microorganisms have been established as critical factors
in the formation of stable humus. The sustainability of water cycles is therefore
dependant on gaining a better understanding of the level of biological activity in the soil
complex. Recent advancements in the study of the soil food web have provided land
managers with a means to identify the types and numbers of beneficial or detrimental
organisms in the soil.
The formation of stable humus can now be enhanced through the addition of biostimulants which are produced to contain specific beneficial micro-organisms for a
specific land use system. The performance of plants and the building of soil humus
levels is dependant not only on the number and type of microorganisms but also on the
ratio of different groups of microorganisms. The interaction and balance of
microorganisms in the soil food web is essential for maintaining a soil complex in a
healthy and robust state free from pests and disease. This healthy state of soil enhanced
by a balance of essential soil minerals is then passed on down the food chain to healthy
plants, animals, and ultimately humans.
36
Algae in the soil are responsible for producing sugars, proteins and carbohydrates which
feed soil microbes. The number of algae in a healthy soil is estimated at over 10 billion
per square meter. The number of bacteria in a healthy soil is estimated at over 600
million in every gram (Sait, Zimmer and Brunetti 2003). A healthy soil should also
contain 8000 to 10’000 different species of fungi as well as nematodes, protozoa,
arthropods and earthworms all of which contribute to a dynamic soil ecology. This
complex web of soil organisms performs the function of continually cycling waste
organic matter and soil minerals into available elements and a stable soil structure for the
growth of higher plants. Mycorrhizal fungi in the soil form a symbiotic relationship in
the soil with plant roots, they break down insoluble plant nutrients from the soil using
strong organic acids and exchange these and water for carbon from the plant (Lovel
2004). The extended hyphael filaments are capable of extending long distances through
the soil effectively enlarging the root zone of plants.
Bio-stimulants may be prepared and applied in the form of controlled preparations of
compost, compost teas or concentrated liquids. Biodynamic microbial stimulants are
specifically designed to lead to strong humus formation using special preparation
methods which harness special earth forces.
The degree of management of soil biology is comparative to managing soil minerals and
other aspects of the entire land unit in the manager’s care. Resources such as labor,
capital and knowledge support are all factors which will determine the appropriate level
of biological enhancement. Biological inputs such as compost can provide the soil with
an immediate increase in beneficial microorganisms and plant nutrients acting as a
catalyst for improved biological conditions and the formation of additional humus.
While mineral and biological inputs can significantly increase the rate of soil
improvement, improved management using holistic principles is undoubtedly the most
important resource in enhancing natural resources. Extensive low input farming systems
can improve soil structure and fertility through strategic grazing systems, cover crops or
green manures. An increase in organic matter brought about through improved
management techniques will increase soil biology and ground cover and will ultimately
increase the level of soil humus and water-holding capacity.
7.3 Mechanical Methods for Improving Humus Levels
Inappropriate clearing and tillage of soils has been a major contributor to the decline of
soil humus in Australian soils. Total carbon levels in conventional cultivation systems
can decline by 55 -63% over 60 years with more than half of the decline occurring in the
first 3 years (Bowman et al. 1990). The greatest decline in soil carbon following
cultivation occurs to the more labile fractions (active humus). Water aggregate stability
37
and soil hydraulic conductivity were found to be negatively affected by the decline in the
labile fraction of organic carbon (Whitbread et al. 2003).
Ideally land management systems which minimise cultivation and increase ground cover
provide the most sustainable means of increasing soil humus and water storage. ‘Pasture
Cropping’, is an emerging cropping practice now being developed to sow crops directly
into living pastures to maintain soil life and soil structure (Martin 2001). Other biological
cropping systems minimise tillage and use it as a tool in a similar manner to pulse grazing
methods. The carbon captured in plant material is incorporated into the surface layer of
the soil as green manure to maximize biological activity and increase humus formation
without destroying the soil structure of deeper horizons. Deep ripping is another form of
tillage which can benefit humus formation by aerating soil which has previously been
compacted by livestock or machinery.
7.4 Green Manures
Green manures are crops which are grown specifically to be incorporated into the surface
layer of soils, adding large quantities of organic matter. Green manures can be selected
to supply the soil with either structure building carbon material or the raw material to
produce high quantities of nutrient rich extracellular material. “The fresh plant tissues of
green manures contain more available sugars, amino acids, enzymes, vitamins and other
cell materials than dried residues” (Zimmer 2000, p.255 ). As the formation of stable
humus is dependant on a combination of active humus and lignin derived humus, a
program which aims to supply both young material and older lignified organic matter will
be of the greatest benefit. The ploughing in of green manure has been shown to increase
active humus by 8.6% and tightly combined humus by 2.5% increasing both field
capacity and available water capacity (Xiong & Cheng 2003). Green manure crops used
in large scale organic farming systems have been reported to raise organic carbon levels
by 2% over 10 years (McNally 2004).
Land management systems and techniques which have been developed to maintain the
life building processes in the soil complex are often described as alternative agricultural
systems, although it is within these systems that agriculture has the greatest potential to
sustain biological life, water and food supplies across an indefinite time frame. A more
logical and intelligent view may be to describe the accepted system of conventional
agriculture developed in the first and faltering industrial revolution as the alternative and
unsustainable agricultural system. The formation of this system has been developed from
alliances between political institutions and the might of synthetic chemical companies
without due consideration for the biological health of the environment and the vital
resources which it supplies.
38
The implementation of sustainable land management systems should no longer be an
option for a minority of ecological guardians to practice. The security of national water
supplies and the functions of the hydrological cycle are dependant on recognition that the
life building processes of biological farming systems must be adopted as mainstream
systems of land management. The building of soil humus levels by permaculture
designers using a holistic approach to agro-ecological management aptly describes the
inter-generational philosophy of natural systems. By designing systems which enhance
the creative patterns of nature to increase fertility and yield, and trap and utilize available
carbon, nitrogen and water they establish a system which functions with a dominant
pattern whereby; “Life accumulates Life” (Mahon 2003).
A major form in which life accumulates is soil humus. Through soil humus, water and
nutrient levels increase and all other lifeforms are supported.
Chapter 8 Co- Incident Benefits of Organic Carbon Sequestration
8.1 Reducing Carbon Dioxide Levels in the Atmosphere
A major co-incident benefit of developing carbon sequestration methods in management
systems is the removal of carbon dioxide gases from the atmosphere. At present the
increasing rates of carbon dioxide being released into the atmosphere threaten to bring
about widespread disasters through climate change.
Forecasts from the Hadley Centre of the Meteorological Office in the United Kingdom
forecast that if action is not taken to combat climate change, by the 2080s:
 Global temperatures will rise by about 3ºC;
 Large parts of northern South America and central southern Africa could lose
there tropical forests;
 Some 3 billion people could suffer increased water stress;
 Around 80 million people could be flooded each year due to rising sea levels.
 About 290 million extra people could be at risk from malaria;
 The risk of hunger in Africa will increase due to reduced cereal yields
(Yencken and Wilkinson, 2000)
Hydrological cycles are forecast to be increasingly affected by climate change, including
changes to soil moisture, groundwater and run-off. Additionally the intensity and
frequency of monsoonal systems and the El Niňo-Southern Oscillation is likely to be
altered (Yencken and Wilkinson 2000).
Carbon sequestration initiatives to improve local hydrological systems may have the
additional benefit of reducing the rate of climate change. By applying recommended
management practices to sequester soil organic carbon the total potential for carbon
sequestration in the United States has been estimated at 144 to 432 million tonnes per
year. Follett and Kimble(2003) state, “ With the implementation of suitable policy
39
initiatives, this potential is realizable for up to 30 years or when the soil C sink capacity is
filled. In comparison, emission by agricultural activities is estimated at 43million tonnes
C/y, and the current rate of soil organic carbon sequestration is reported as 17 million
tonnes per year.” Annual carbon sequestration in the United States using recommended
management practices, is estimated at, 280 -620 kg/ ha for cropland, 40 – 200 kg / ha for
grazing land and 100 – 430 kg /ha for forested lands.
The British Royal Society has estimated potential carbon dioxide sequestration on the
worlds 2.5 billion acres of agricultural soils at 6.1 to 10.1 billion U.S. tons per year for
the next 50 years (Sayre 2004).
8.2 Cooling Land Temperatures, Reducing Fire Risk and Creating Local Rainfall
The heat conductivity of humus is said to be poor due to the positive effect it has on soil
tilth, excessive evaporation and improved infiltration (Waksman 1936). The typical dark
color of humus reflects less heat than mineral soils or sands and together with the
increased water vapour produced by a greater degree of plant growth, helps to reduce the
overall temperatures of the land surface. This effect has been witnessed in holistic
grazing systems where the increased humus levels and active plant growth have resulted
in extinguishing the effects of wildfires on property boundaries (Archinal 2004). The
higher water- holding ability and increased transpiration effects of natural farming
systems will be of significant importance in reducing the impacts of an increasingly
warming climate, due to climate change. The dark color of humus and its ability to
absorb radiant heat results in soils remaining cooler in summer and warmer in winter.
Soil humus effects rainfall by supporting a higher degree of vegetational diversity and
retaining more water in the soil to be extracted and exchanged for carbon dioxide in the
process of photosynthesisation. Hamblin, cited in Yencken and Wilkinson (2000, p. 241)
Vegetational diversity is at the heart of biodiversity. The association of groups of
plant species in characteristic associations, provide habitats (shelter, food and
breeding places) of most of the world’s fauna and microbial life forms. This
diversity is in response to localised differences in soil, landform and microclimate, so that the value here is a reciprocal one – with vegetational diversity
dependant on soil, water and topography.
Hamblin has recognised the need to view all aspects of a functioning ecosystem in a
holistic manor, with soils dependant on plants, rainfall and topography, and rainfall being
dependant on soils, topography and plant life.
Mollison (1992) notes the important role that plant life performs in maintaining
hydrological cycles. Trees and other plants through the processes of condensation,
evaporation and transpiration can account for up to half or more of all moisture returned
40
to the air, the moisture constantly returning to the earth as rain and constantly transpiring
back through plants to the atmosphere in exchange for carbon dioxide. Management
practices which fail to view the entire landscape as a complex integrated system will
invariably lead to a breakdown of the vital support systems which life depends on. The
focus of this report on increasing soil humus to increase soil water holding capacity can
be viewed as only one very small part of a far greater cycle of the grand material cycles.
8.3 Humus and Human Health
Increasing rates of disease in the community are raising the level of research into the
links between human health and soil health, particularly the links between soil minerals
and health. Albrecht (1975, p.187) stated that, “we are about to realise that good health
lies very near to good fertile soil”. Thirty years later, there is a multitude of diseases
which are increasing at an alarming rate, including obesity, epidemic levels of cardiovascular disease, diabetes, cancer, arthritis and other autoimmune diseases. It is the
breakdown of important physiological functions due to mineral deficiencies which is
causing the greatest concern (Brunetti 2003). Brunetti (2003) notes, a deficiency of
magnesium and zinc can account for over 300 physiological malfunctions. Physiological
processes such as DNA replication, digestion, immune function, endocrine synthesis,
neurological activity, energy storage and release, muscle contraction and many others
rely on catalysts, usually in the form of enzymes. Brunetti (2003) states, “all enzymes,
without exception, are built on the presence of micronutrients”.
By using the sustainable practices of natural farming systems to build up soil humus, the
nutrient status of a soil can be dramatically improved. Zimmer (2000) notes some of the
nutritional benefits that humus adds to soil, humus:
 Acts as a storehouse of plant nutrients; including 90 to 95 percent of the soil’s
nitrogen , 15 to 80 percent of phosphorous, 50 to 70 percent of sulphur, potassium
and trace elements
 Increases the available supply of crop nutrients, releasing them from tied up
forms.
 Chelates minerals and holds them in an available form.
 Increases the soil’s cation exchange capacity. The humus colloid holding 30 to 70
percent of a soil’s nutrient-holding capacity.
 Stimulates plant growth and health by providing hormones, vitamins and
enzymes.
Albrecht (1975, p.52) through his deeper understanding of soil and plant processes
documented the need to connect human health with soil health, he states, “we have not
yet understood, nor appreciated, agriculture as a collection of complex, but well41
integrated, biological processes. We have comprehended some fragments of this natural
art which science has studied deductively, but we have not yet constructed the whole of a
scientific agriculture inductively. We have not seen the soil as plant nutrition and thereby
as animal and human nutrition, or the soil as the very foundation of all agriculture.”
The implementation of sustainable management systems which recognise soil humus as
the foundation of land management has the capability to restore not only environmental
processes, but also the levels of human health in society.
Chapter 9 Conclusion - The Sustainable Revolution
During the first industrial revolution separatist technological and scientific decision
making has been applied to land resources and water supplies without an understanding
of the biological processes which govern the creation of natural hydrological and nutrient
cycles. The policy of extracting water from rivers in large dams for agricultural and
urban needs failed to ensure that the groundwater sources of river flows were managed
sustainably. Replacing natural fertility with synthetic chemicals, although heralded as a
green revolution due to increased yields, actually deteriorated the soil biological and
physical conditions needed for sustainable water supplies and disease preventative food
production.
The mining of soil humus without due recognition of its importance in soil structure and
water-holding capacity has also lead to devastating land degradation and a serious
alteration to atmospheric carbon levels.
A Global Environment Outlook report conducted by the United Nations Environment
Program (1999, cited in Yencken and Wilkinson 2000, p.26), concluded that the decision
making processes of the past century have resulted in a situation where:
The world water cycle seems unlikely to be able to cope with demands in coming
decades, land degradation has negated many advances made by increased
agricultural productivity, air pollution is at crisis point in many major cities and
global warming now seems inevitable. Tropical forests and marine fisheries
have been over-exploited while numerous plant and animal species and extensive
stretches of coral reefs will be lost forever – thanks to inadequate policy
response.
The results of the first industrial revolution are conclusive. Water supplies, fertile soils
and even the atmosphere have been so degraded that global material cycles are now in
crisis.
42
Sustainability for future generations is now dependant on a new revolution, a revolution
whereby the productivity goals of society are achieved by stimulating the integrated
creative capacities of natural systems. Savory (2004) states, “over-grazing, overstocking
and over-population were not the problem; rather, it was conventional decision making
processes used by governments, organizations and individuals that simply did not provide
a framework to manage natural systems”.
The complexity of the natural systems requires a broader level of understanding than
previous scientific disciplines have held. The sustaining of water supplies and soil
production is no longer dependant on how much we can modify a system, but on how
much we can enhance the natural creative processes within that system.
By using non-destructive management practices in well designed land management
systems, the foundation of life, soil humus can be accumulated and used to store valuable
falls of rain across catchments. Gradually the re-charged ground water system would
release a continuous supply of water to river systems and the atmosphere, as
transpiration, to restore hydrological cycles and sustain the ‘Water Supplies of a
Nation’.
Environmental stability, production efficiency, biodiversity enhancement and social
justice are all achievable outcomes under a new revolution, where the enhancement of
soil humus is the first priority of a sustainable society.
The Jewel of Humanity and the Soul of the Earth ~ Humus
43
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