ENABLE

ENABLE

NEWSLETTER OF THE ASSOCIATION

FOR BETTER LAND HUSBANDRY

NUMBER 17(w), JULY 2003

Contents

Editorial Transformations

Articles ‘Fire’ in the Soil – B.A.Stewart

Productive Pastures: Benefits for the Farmer and for the Environment

- Bruno J.R.Alves, Segundo Urquiaga, Robert Boddey

‘Indian Agriculture a Big Winner from A C I A R Project’

Why Better Land Husbandry ? – Francis Shaxson

Better Land Husbandry Comes of Age – FAO / WB

The Universal Soil-Loss Equation or A Universal Soil-Gain Equation ? - Francis Shaxson

Tropical Soil Management – 4 Papers from the Workshop

- F.Shaxson - D.Powlson - H.Gunston - S.Bunning

Book Reviews

Soil and Water Conservation in Honduras : A Land Husbandry Approach – Jon Hellin

Conservation Tillage & Cropping Innovation : Constructing the New Culture of Agriculture

- C.M.Coughenor and S Chamala

Bookshelf Something New Under the Sun : An Environmental History of the Twentieth-Century World

– John McNeill

FAO’s Latest Publications and Activities Regarding Conservation Agriculture – FAO

A.B.L.H. & T.A.A. The Linkage

Misc. Bits Think-pic 5 Conservation Buffers – Are They Talking about Us?

EDITORIAL

TRANSFORMATIONS

With the venturing-forth of ABLH-Kenya as an autonomous Kenyan NGO two years ago, the original prime purpose of ABLH in UK was fulfilled, and our Association’s ‘raison d’être’ was reduced accordingly. Nevertheless, our Constitution also refers to the aim of dissemination of relevant information about land husbandry, and - despite the small membership of ABLH – it seems that this activity has been relatively successful over the years, whether via the inputs made by land husbandry aficionados in the course of various consultancy visits in different countries, speaking at meetings and Conferences, the ABLH website, and/or through the publication of ENABLE at more-or-less-regular six-monthly intervals.

As a result of all this, extracts from the final draft Executive Summary of a 2002 document by FAO, which are reprinted in this issue, indicate that Better Land Husbandry has now come of age – the subject is now ‘over the threshold’ of wide acceptance. This is also evidenced by the vast number of Web-pages under ‘Land Husbandry’ that are found today by comparison with the very small number of citations only three years ago. So it has been worth the effort!

With a slowly-diminishing membership it has not been realistic to go for ABLH’s expansion into new activities. But rather than let ABLH fade away, it was felt to be important to become affiliated with another organisation of broadly comparable interests. As a result of agreeable discussions,

ABLH has now become a Specialist Group within the significantly larger Tropical Agriculture Association in UK. This allows us not only to maintain our specific identity but also to interact in-house with others having land-based experiences of the tropics and sub-tropics, so that we can both gain and offer such information, to mutual benefit.

The TAA has already kindly enabled us to have our own place within its website - http://www.taa.org.uk . Both ENABLE-15 and ENABLE-16 (‘Struggling to Survive Poverty’) now appear there in the section ‘Published Papers’.

This issue of ENABLE may be the last in the present printed format. In future it is proposed that articles of land husbandry interest be offered to the main TAA Newsletter, and to build up the ABLH portion of the TAA website by gradually transferring relevant papers from the old ABLH website into this section, and to put any future issues of ENABLE there as well. I am very grateful to Dr A. Smith, who manages the overall TAA website, for suggesting such an arrangement. This will be relatively simple and inexpensive to operate, and will extend the range of our readers to beyond our own limited circle of faithful members.

The Editor

“Soil organic matter is an important component of soil because if affects all soil processes --- chemical, biological, and physical. Perhaps most important in semiarid regions is the effect that soil organic matter has on the infiltration of precipitation and on the water holding capacity of the soil. It is well known that as the content of soil organic matter declines that the infiltration rate decreases and the amount of plant available water that the soil can hold becomes smaller. These effects are negative in all areas, but they are particularly bad in semiarid regions because they make the lack of water even more lacking. Loss of soil organic matter also leads to increased wind and water erosion and this only exacerbates poor soil water conditions. Soil organic matter serves as a “glue” to hold soil particles together and its loss greatly accelerates the erosion hazard. Soil organic matter loss also destroys soil structure that is so important in soil water properties.

Soil organic matter decline is common in all climatic regions where agroecosystems are formed. Tillage is the main cause of soil organic matter decline and the more intensive the tillage, the higher the rate of loss. The negative effect generally increases with increasing aridity because the initial soil organic matter content is usually low and the amount of biomass produced annually to replenish the supply is limited because of the lack of water. An analogy illustrating the effect that tillage has on soil organic matter decline is the burning of logs. Once the fire starts, the flame burns high and fast but after a while, the fire dims. What do we do? We take a stoker and stir the logs. WHAM! The fire gets bigger again. Why? Because we did two things --- first, added oxygen that is required for a fire; and second, exposed new surfaces that had previously been protected by overlying logs. The flame gets bigger after stirring, but it does not get quite as high as before, and does not last as long before it begins to subside again. We repeat this process over and over until either the fire goes out, or we add more firewood. This is very similar to what happens when we till the soil. There is always a fire in the soil --- the biological activity of microorganisms. When we till the soil, we add oxygen and expose new surfaces and the fire becomes larger. And, the more intensive and the more often the tillage, the more we burn out the soil organic matter and degrade the soil.

When we burn logs, we create ashes. The same is true when we burn soil organic matter. The ashes contain N, P, K, Ca, Mg, Mn, Fe, Zn and all the other nutrients essential for plant growth. Although these ashes result in good crop production, the soil physical properties are being degraded unless we are ADDING MORE FIREWOOD to the soil. Otherwise, the ashes become depleted and the first nutrient that is usually lacking is N. We often add N fertilizer to correct this deficiency, and then we run short of P, and then K, and so on. All the while, we continue to degrade the soil physical properties and decrease the amount of biological activity. Growing legumes and adding manures are good practices to reduce these losses, but these practices are more difficult to carry out in dryland regions than in humid conditions. Therefore, soil organic matter decline is a major problem in dryland regions and one of the best ways to address this problem is to reduce tillage to the fullest extent possible by using the principles of conservation agriculture”.

¹Pers. comm. from Dr. B.A.Stewart, Distinguished Professor of Soil Science, and Director of the Dryland Agriculture Institute, West Texas A&M University, U.S.A. Reprinted with his permission.

.oOo.

THE LAND BEREFT

“If society forgets or no longer cares where it lives, then anyone with the political power and will to do so can manipulate the landscape to conform to certain social ideals or nostalgic visions. People may hardly notice that anything has happened, or assume that whatever happens – a mountain stripped of timber and eroding into its creeks - is for the common good. The more superficial a society’s knowledge of the real dimensions of the land it occupies becomes, the more vulnerable the land is to exploitation, to manipulation for long-term gain. The land, virtually powerless before political and commercial entities, finds itself finally with no defenders. It finds itself bereft of intimates with indispensable, concrete knowledge.”

Barry Lopez. About This Life. Harvill 1998. p.138.

.oOo.

“PRODUCTIVE PASTURES:

BENEFITS FOR THE FARMER AND FOR THE ENVIRONMENT

Bruno J.R.Alves, Segundo Urquiaga and Robert M.Boddey

of the EMBRAPA-Agrobiology unit.

Research shows the key to the accumulation of organic matter in the soil

Recently, research undertaken by the Nutrient-Cycling Group of Agrobiology within EMBRAPA [Brazil’s national agricultural research organisation], together with EMBRAPA-Wheat and EMBRAPA-Soya, not only confirmed the superiority of direct-planting [= ‘direct-drilling’, ‘zero-tillage’, ‘no-till’] systems in the accumulation of organic matter in the soil, but also showed that it is a process highly dependent on the availability of nitrogen in the soil. Under direct-planting, quantities of organic matter were accumulated in the soil when there was a legume for green-manuring in the crop rotation, which had the role of enriching the system with N. In these conditions, crop rotations under direct planting regimes can accumulate in the soil around 1 ton more of organic matter per year in each hectare when compared with conventional systems based on the use of [disc-] ploughs and –harrows.

Although the areas cropped with direct-planting allow a rise in the carbon content of the soil, it is pastures which present the greater potential to withdraw carbon dioxide from the atmosphere and enrich the soil with organic matter, in quantities which can approximate to levels observed in soil under native vegetation.

Productive pasture is carbon in the bank

In researches in areas of pastures in Bahia, the team from EMBRAPA-Agrobiology stressed the importance of pastures intermixed with forage legumes in the accumulation of organic matter in the soil, which can enable a rate of organic matter accumulation in the soil of between 3 and 4 tons per hectare per year. This is not to say that soil organic matter is only accumulated with the introduction of legumes. What is more important is that the pasture should be productive, because in this condition the soil is being furnished with large quantities of residues, and the nitrogen certainly will be in sufficient quantity to increase the soil organic matter. “One situation leads to another!” As an example of this, there are the results obtained from research in areas of pasture in the ‘Triángulo Mineiro’. There we encounter practically 40% additional organic matter in areas of productive pastures, which support around 3 to 4 animals of 250 kg. weight on every hectare (1.7 to 2.2 Animal Units/ha.)

Importance of integrating of ‘direct-planted’ cropping with livestock production

Unfortunately a large part of the pastures of the country are found to be degraded, caused by the lack of management and only minimal investment made in terms of replacing nutrients in the soil. It is here that the importance of crop/livestock integration is most importance. [Well-managed] cropping guarantees replacement of nutrients into the soil and, when under a direct-planting regime, avoids the loss of soil organic matter, being able even to increase its content in the soil. The residual effects left after cropping keep the pasture highly productive.

The investment made by the producer to raise and/or maintain pasture production immediately translates into money through the increased production of milk and meat. In parallel, the damage to the environment caused by utilization of the land to produce food is diminished by the increase in soil organic matter and by the maintenance of the cover [over the soil] which greatly reduces soil losses.

This also enables the process of intensification of land use to become a substitute for expansion of deforestation as the means of increasing total agricultural output.

The majority of areas of pasture in Brazil could, with application of more-appropriate management, at least double their productivity.

With the strong possibility that such agricultural systems as direct-planting will come to be included in ‘Mechanisms of Clean Development’, a new source of revenue would be guaranteed to producers whose crops and pastures promote increase of soil organic matter. This is what is called the ‘Green Cash’ which pays for environmental services provided by the farmer and is qualified as one such mechanism. It is hoped that the rules for such mechanisms will be determined at the November meeting in Milan”.

As reported in ACIAR Newsletter No. 38, ACIAR’s support of zero till agriculture and management of herbicide-resistant weeds in India is helping to deliver substantial gains in agricultural productivity, farm incomes and the sustainability of agricultural land.

Now an independent evaluation has predicted gains to India of $1.8 billion over the next 30 years from the adoption of these methods in northwest India. But the eventual gains could be much more than this as the technology spreads through other regions and neighbouring countries.

The project was designed to address a serious weed infestation problem in the rice-wheat cropping system of northwest India – a region containing 3 million hectares of cropping land and accounting for around 35% of India’s wheat production. By the early 1990s the weed Phalaris minor had developed resistance to the herbicide used to control it. There was a massive decline in wheat yields – between 30 and 80% on individual farms over an area of 1 million hectares.

New herbicides were introduced as a short-term solution. But these are expensive. Adoption was poor and the development of chemical resistance in the future a certainty. What was needed was a long-term solution that would be commercially attractive to farmers. ACIAR-funded scientists, working in conjunction with their Indian counterparts, have developed a control package centred around dealing with the phalaris through changes to farming practices, including incorporation of zero tillage cropping.

The result has been spectacular.

· big cost savings in cultivation;

· yield increases through early sowing of wheat;

· better weed control with reduced reliance on herbicides; and

· avoidance of soil degradation and yield declines through continuous cultivation.

The evaluation, undertaken by David Vincent and Derek Quirke from the Centre for International Economics, provides further evidence that the stage is now set for a second ‘Green Revolution’ in the region.”

In ENABLE no. 15, July 2002 I wrote an article entitled ‘Why Better Land Husbandry? This time I use the same set of words but place the emphasis differently.

I suspect that many people assume that what we really mean is the better management of soil, and that the word ‘land’ is an unnecessarily fuzzy way of trying to carve out a niche for ABLH.

Not so.

Land is more than just the layer of soil in which plants grow: it also has three-dimensional shape(and changes over the fourth dimension – time). Land husbandry aims to maintain its lasting usefulness for the purposes which we choose. In rural situations more specifically, it is concerned not only to sustain the capacity of its soils to provide for plant growth but also – where conditions allow – at the same time to safeguard its capacity recurrently to yield clean water seeping from the catchments into which it is shaped, and from the subsurface water which is found beneath.

Sustainability of these two capacities depends on maintaining soil porosity so that rainwater can get into, and beyond, the root-zone without avoidable loss by runoff and/or direct evaporation. Organic matter, organisms and their interactions in organic processes contribute to generating and regularly renewing water-stable aggregates on which infiltration, retention and percolation of water depend, and from which both plant production and streamflow are derived.

The previous article of the same title as this (but with its other emphasis) complements this one, and vice versa, as you will perceive.

(i) A vibrant agriculture is of crucial importance to the future of Sub-Saharan Africa (SSA). Achieving this will require that the nearly 70 million smallholder farm families in the region widely adopt improved and sustainable crop, land and water husbandry practices within the next decade. . . .

(ii) During the last decades, agricultural performance in SSA has generally been poor and output has changed little since the 1970s. In countries where total crop production increased, this was mostly the result of increases in cultivated area. . . .

(iii) Many SSA smallholders face constraints in adopting viable practices to increase and use efficiently organic and mineral fertilisers. As a result, they withdraw much larger quantities of plant nutrients (N, P and K, secondary and micro-nutrients) than are being replaced, with the result that soil organic matter content and biological activity decrease, physical properties deteriorate and moisture-holding capacity goes down. In short, soils are "mined", "soil health" deteriorates, and the efficiency of fertilizer and water use decreases. SSA farmers find themselves in a "vicious cycle" of lack of knowledge and resources, declining productivity and increasing poverty.

(iv) The key objectives of the World Bank's 2002 Rural Development Strategy for SSA (reduce poverty, promote growth, protect the environment) and of the New Partnership for African Development (NEPAD), cannot be achieved if smallholders, who farm around 180 million ha of land in annual and perennial crops, do not sustainably intensify their production systems and expand cropped areas, where appropriate. Achieving this requires, as a crucial component, greatly improved crop and land husbandry. Because of the close interactions between crops and animals in many SSA farming systems, livestock production will be affected as well. . . . The "Soil Fertility Initiative" (SFI), launched in 1996 in response to concerns of SSA stakeholders. . . . had, as its original goal, the introduction and adoption of sustainable soil fertility management practices by smallholder farmers.

Achievements and Lessons Learned

(v) Consultations on the SFI between lead sponsors. Government entities and other stakeholders in about 20 SSA countries resulted in almost all countries endorsing the SFI and requesting assistance in the preparation of action plans. . . . Only limited resources were allocated to the SFI, and although it has made significant achievements, implementation has been haphazard and piecemeal, with negligible impact so far in relation to the overall magnitude of the soil fertility/productivity problem.

(vi) However, the SFI has stimulated a rich debate on sustainable soil fertility and land productivity management and in several countries, there is now a better appreciation of soil productivity problems and a clearer vision of the complex set of actions needed to effectively address soil fertility deterioration and achieve long-term productivity improvement. . . . The SFI concept itself has, during the past few years, evolved beyond a narrow approach of soil fertility enhancement largely through external inputs of mineral fertilizers and the use of leguminous crops and trees. It is also increasingly accepted that the SFI must, to be successful, concern itself - in addition to institutional and policy issues - with all those aspects of soils that affect their ability to support farming on a sustainable basis, including their physical, chemical and structural properties, biological activity and moisture holding characteristics.

(vii) The problems of low farm productivity in SSA cannot be solved through isolated solutions such as increased use of mineral fertilizers, hybrid seeds, irrigation or mechanization alone. Rather, an integrated approach, which addresses soil productivity problems as a core element of sustainable land management for agricultural production, is needed. Significant and lasting improvements will be achieved through the positive synergies resulting from the combined adoption of improved crop/plant, soil and rainwater management practices that offer both production and environmental benefits. Thus, although not yet formally endorsed, the original SFI concept has evolved towards the so-called "better land husbandry" (BLH) approach [my bold – Ed.]. To reflect this thinking well and to promote a clear message, there appears to be a case for re-naming the SFI as the "Africa Land Husbandry Improvement" or "Sustainable Land Management" Programme. . . .

The Way Forward

(xiii) During the next decade, there is an unprecedented challenge to improve soil management, enhance productivity, develop sustainable farming systems and environmental protection on a significant part of the cultivated area in SSA. From being trapped in a vicious cycle of increasing poverty, SSA smallholders can be facilitated to reach a "virtuous cycle" of improved knowledge and understanding, leading to good land husbandry practices, increased productivity and significantly improved livelihoods. This will involve an approach that incorporates the interdependency of the organic, mineral, biological and physical aspects of soil management, with organic matter and mineral fertilizers being complements rather than substitutes, while recognising the site-specificity of development options for farming systems . . .”

The Universal Soil Loss Equation has been used in many places and for many years to estimate likely losses of soil by water-erosion processes. It has widely been assumed that this provides a reasonable basis for estimating the effects of erosion on plant yields (though I believe that the philosophical - let alone the technical - justification for this is debatable – see ENABLE-15).

It is worth pointing out that

a. The principle underpinning the assumed direct soil-loss/yield-loss linkage has not been satisfactorily defined, being assumed much more often than it has been clearly demonstrated by experiment;

b. The closeness of the USLE model’s soil-loss estimations to in-field realities have in many situations not been satisfactorily cross-checked, with the result that decisions on policy and actions relating to plant production in particular, based on the model’s results alone, may be of questionable validity;

c. After decades of experimentation across the world the policies, strategies, tactics, and implementations adopted to deal with the problem of soil erosion, based on the USLE model, have not of themselves been particularly successful both in eliminating the erosion problem and simultaneously stabilising or raising average yields.

These points suggest that a radical re-appraisal of the approach to land degradation by erosion and associated declines in soil-productivity is justifiable and needed. This should be undertaken urgently, no matter how many sacred cows need to be subjected to veterinary-style examination as to their continued productivity and, where necessary, be deconsecrated and relegated to the back pasture.

A Soil-Gain Equation. Now take another look at the photo on p. 26 of ENABLE # 15 – July 2002, and then at ‘Think-Pic 2’ on p. 23 of ENABLE # 14 - February 2002 (in that order) and a different perspective becomes apparent.

If plant-favourable soil is developing from the top downwards much more than from the bottom upwards under influence of organic materials and processes, then an appropriate approach to the problem becomes that of actively enhancing the quality and depth of the soil also from the top downwards. Now DMC –‘Direct Sowing, Mulch-based systems and Conservation agriculture’ (see e.g. pp. 12-15, 23 of ENABLE # 15) come into their own.

It seems likely that more-direct linkages between soil improvement (particularly in terms of organic materials and processes, and of soil porosity)and biomass- yield of crops, grasses, shrubs and trees could be more-accurately predicted using some form of ‘Soil-Gain Equation’ than has been possible with any form of Soil-Loss Equation.

This view of the problem and of the approach to its solution is validated by the growing number and range of positive experiences by farmers, their advisors and researchers after implanting zero-tillage/DMC systems on their farms and ranches in Brazil and other countries.

The results of better land husbandry, of which this is a part, is giving rise to policies, strategies, and tactics which please both people and the environment.

It may prove complicated to determine a soil-gain:yield-gain relationship, but the philosophy and principles behind it will be more comprehensible, and the consequences in the field more positive, than they have been up till now.

‘I should like to welcome all of you this afternoon and particularly our guest speakers. We have a relatively small attendance but as we shall discuss tomorrow at the AGM we are planning to merge with the TAA to gain the advantages of a larger grouping.

‘We had hoped to have a paper from the National Soil Research Institute, the successor to the Soil Survey of England and Wales. We know that there has been quite a considerable amount of investigation on the impact of changing land use in the UK on, for example run-off, and this is obviously a topic of interest in the tropics too. Unfortunately a speaker was not available.

‘Agriculture has become substantially neglected by the donor agencies. You will recall that the DfID White Paper on “Eliminating Poverty” scarcely mentioned agriculture. The subsequent paper on agriculture did admit that the greater proportion of poverty was in rural areas and that improvements in agricultural productivity would be essential if we were to make inroads on this. That agriculture is in dire straights in many countries, particularly in Sub-Saharan Africa, is not in doubt – 35 million people needing food aid this year. Some countries like Ethiopia and Malawi have structural problems such that they cannot produce enough food, even in a good year, to tide them over the bad ones. And of course the spectre of HIV/AIDS is having an enormous impact where 90% of the energy used in agriculture is human energy. The report by Patrick Hamilton, circulated by Francis, who has been monitoring the ABLH project in Kenya, on the impact of decreasing size on land holdings on poverty, especially on the ability to pay school fees, reveals just how serious the problem is.

‘Today and tomorrow we shall hear about some of the problems of land deterioration – an insidious and not always directly obvious situation and thus the more difficult to reverse, but one with long term implications. The obvious signs are usually mentioned in passing – the estimates of the area that is being lost through erosion or salinisation but the more insidious aspect of structural deterioration is scarcely mentioned. Much attention is given to farmers’ assessment of their problems but I wonder whether farmers are aware of the more insidious aspects of land deterioration. We shall hear about some of these from our speakers and about how these are being tacked in several parts of the tropics. In welcoming you I am sure we all look forward to a series of interesting presentations and discussions.

Mr Shaxson started by saying that he wanted to be passionate about soil porosity and organic matter, both being of fundamental importance to much-needed increases in food production. He pointed out the dilemma in trying to increase crop production – it requires more water at a time when the demand for water consumption is already increasing beyond the available supply. He said that this situation is exacerbated by soil compaction and by plough and hoe layers which reduce the capacity of the soil to hold water available for plant roots. The following is a summary of his presentation in which many of the points were illustrated with copious photographs and diagrams.

Think like a root

We face two interlinked problems in the quest for higher output from the land: (a) intensified use of land generally leads to more land degradation; (b) ever more clean water is demanded, but increasing proportions of rainwater are lost as muddied runoff. Land’s productivity for plants and for water are linked to the landscape. But the hydric component of the productivity of soils – interacting with the chemical, physical and biological components – is not sufficiently highlighted. It is useful to think like a root and think like a river in order to visualise the landscape conditions needed to sustain the capacities to provide plant biomass and streamflow.

Tillage and porosity

Tillage has some adverse effects on tropical soils. Degradation of optimum porosity in the soil diminishes soil capacities for both infiltrating rainwater, retaining it at plant-available tensions; and enabling through-flow of surplus to groundwater and thence to streamflow. Tillage in tropical conditions speeds the rate of oxidation of organic matter and emission of CO₂ from soils, enabling structural collapse, as well as resulting variously in loss of useful spaces within the soil architecture due to pulverisation, compaction, interstitial sealing, and closure of biopores. Soil profiles become less retentive of water, increasingly subject to runoff and erosion, less favourable to root growth and function, even to the extent of preventing root penetration below the tilled layer. Such damage can follow from use of hand-held and mechanised equipment, and from the repeated passage of feet especially on soils in a wet state. The condition of the soil – at and below the surface – affects the partitioning of rainfall between entry into the soil and runoff, and hence the efficiency of use of scarce rainfall. Economic as well as biological consequences of such soil damage are shown to be severe. The effects of water-stress in plants on their final yields are far more quickly noticed than are those of soil loss.

Organic matter and processes

Soil-inhabiting organisms have very significant effects on the self-recuperation of the porous architectural condition of most soils, as long as they are regularly supplied with organic matter as a food source. Useful soil is formed from the top downwards by their combined effects, as long as there is sufficient moisture for their activities in transforming organic materials. Water plus organisms (including plants) plus organic matter provide a common thread linking self-recuperation of soil, its resilience in the face of shocks, the sequestration of carbon, functioning of ecosystems, health of soils, and sustaining their productivity. Problems resulting from deforestation, overgrazing and excessive cultivation are best addressed by attention to protecting and improving soil porosity, soil organic mater and soil processes rather than by often-ineffective legislation. In trying to solve land-damage it is necessary to think, not only at the macro scale, of land allocations and policies, but also at the micro scale, of soil pores and bugs.

Better land husbandry in Brazil

In Brazil the development over the past 30 years of improved agricultural systems; which involves:

· planting directly through retained crop residues;

· using cover-crops/green-manures to augment the feed for soil organisms;

· avoiding disturbing the soil by tillage;

shows marked benefits to a total area still rising beyond the 19 million hectares recorded in 1999. These benefits include:

· great improvements in the amounts of plant-available moisture in soils;

· associated improvements in streamflow

· reductions in runoff and erosion;

· more stable crop growth and yields;

· greater diversity;

· increased efficiency of utilisation of inputs.

Resulting from these benefits, there are associated social and economic benefits at farm level. In addition, these are accompanied by improved environmental, social and economic conditions at the level of communities, landscapes, river basins and the country as a whole.

Discussion

Much discussion followed on how these desirable improvements could be developed among resource-poor small farmers in densely-settled areas of the seasonally dry tropics and sub-tropics. It was noted that soil conservation based on civil engineering often became a solution in search of a problem. The initial problem of weeds where no-till farming was introduced would require the increased use of suitable herbicides.

Dr Powlson reiterated that increasing soil organic matter brings many agricultural benefits, including aggregate formation and stability; decreased capping, capping and erosion; better water infiltration and retention, improved, seedling emergence, nutrient supply to crops and workability. Soil carbon is also important globally - because there is so much of it, it can help to mitigate climate change. However, increasing soil organic matter content is not easy, especially in tropical climates. We can use more animal manure, crop residues and other wastes; grow intercrops, including perennials; adopt minimum tillage, grow trees, bioenergy crops, use set-aside and wider field margins or grass instead of arable crops; grow green manure, pasture or pasture/arable rotations; or grow larger crops by using fertilizers. Long term experiments with these are valuable in showing the soil organic matter changes that may be possible, but such measures may not be practicable in farmers’ circumstances.

There are limitations to the sequestration of carbon in relation to reduction of global warming. It should be seen as additional to decreasing fossil fuel CO₂ emissions – not an alternative. Minimum tillage itself gives benefits for ‘soil quality’, but data from Brazil show that carbon is increased only in the undisturbed surface 15cm or so. Taking the soil profile as a whole, the effect of tillage on organic carbon content is less clear. It is possible to have too much soil organic matter, with large applications of manure losses of N and P to stream flow may rise. Usually however carbon sequestration is beneficial – for both soil quality and the environment.

Discussion

Dr Powlson mentioned discoveries of high soil fertility in sites of ancient cultivation which are associated with incorporation in the soil of elemental carbon in the form of charcoal particles. To decide whether soils are getting better or worse as a result of some intervention, the measurement of total C is inadequate. It is more useful to measure the living soil micro biomass, which responds more quickly to changes. Techniques involving the physical fractionation of organic matter have also proved helpful.

Mr Gunston said that the uses and management of water overlap in rural communities and it is essential to adopt an integrated approach – balancing water needs and availability. His talk was illustrated with examples of field measurement equipment, Archimedean screw pumps and hand pumps which are now “the thing”. Satellite imagery showed contrasting areas of soil moisture and plant stress. The effect of cover crops or mulches on soil moisture after rainfall revealed the potential for soil moisture management. He compared the water requirements of different crops, stressed the need to turn the collected data into economic reality and raised the question – how can we improve water management?

Water for “Tropical agriculture” is taken here to include rural demands for water by:

· crop and livestock production

· village communities;

· forestry – commercial timber, catchment protection, amenity / environment and agroforestry;

· environmental interests – wetlands, national parks, and eco-tourism.

The various water-related measurements that may be made to assist “tropical agriculture” include:

· rainfall;

· channel flow – rivers, streams and irrigation canals;

· soil erosion assessments from rates of runoff, sediment and bed loads;

· evaporation – including sophisticated research techniques;

· rates of interception by forest canopies;

· soil moisture;

· soil infiltration rates.

· measurements linked to water quality, groundwater and water supply – for example, pump data.

There is a range of mechanisms for the transfer of information and analysis to farmers and others involved in using and allocating water resources for “agriculture”. These include extension services, workshops and discussion groups at various levels, scientific journals and meetings, and technical guidance and lobbying directed towards policy makers.

However we should be aware of the “pinch points” which restrict the flow of information towards improving practice in the field. These can include the limited availability of journals, academic culture turning graduates away from field activities, poor funding and support for extension services, technical research and dissemination and general bureaucratic inertia.

Discussion

It was pointed out that today it is accepted that irrigation water is also used for domestic purposes although associated health risks were well documented – often due to toxic elements being brought to the surface from deep groundwater. It was also noted that co-operative development in irrigation schemes often led to aquaculture enterprises. Finally, the FAO agriculture website was commended.

In her opening remarks, Sally Bunning said that she had started work in Malawi and at the time things were driven by francophone African research. Under Jose Benites, on the other hand, the FAO group had concentrated on conservation-oriented land husbandry – focused on biodiversity with a strong emphasis on the soil component.

She summarised the main causes of land degradation citing deforestation, overgrazing and tillage. Compaction is now a serious problem as pulverisation by tillage destroys soil voids and prevents water infiltration. Today the need is to improve the rooting environment and promote biological N fixation. Conservation agriculture achieves these aims by maintaining a complete and permanent soil cover with no- or minimum tillage. The cover crop or mulch is not incorporated into the soil but protects the soil and the crop, inhibits germination of weed seeds and provides food for the soil life. She presented a wealth of data and photographs showing that soil structure was improved, biological activity increased, soil and water loss reduced and crop yields increased under conservation agriculture. However, it is not the yield increases that are important so much as the consistency of yields with lower labour demands, making it more cost effective. Labour aspects are particularly important and the effects of HIV/AIDS on food production are of great concern.

However adaptive management is essential and in drier areas conflicts have to be resolved between the use of organic matter to feed animals or to cover the soil. Conservation agriculture can be adapted for different climates, crops and soil types. With suitable crop rotations and after the elimination of weed seed banks, residues do not cause disease and pest problem. Although initially chemical applications may be needed, in the longer term their use is reduced.

FAO has been promoting the concept for 10 years. It has a very active working group running field projects, meetings, workshops and demonstrations around the world. It maintains a series of pages on conservation agriculture, linked from its main website (see for example http://www.fao.org/ag/agl/agll/prtcons.stm), supports databases on the concepts and has published handbooks, bulletins and CD-roms.

Conservation agriculture brings benefits to individual farmers, to communities and catchment areas, and globally – through carbon sequestration and water retention, with less pollution, leaching and erosion. The expansion of conservation agriculture is rapid but it needs higher management skills. There are problems that remain to be solved – for example with the use of jab planters on mulched, compacted soils. However, it is making the optimum use of the potential of soil organisms. Getting carbon from the air into the soil via plants is critically important, and in set-aside situations growing excess vegetable material is a key option. Unfortunately Europe in particular still has policies unsuitable for conservation agriculture, and remains generally ignorant about the concept.

Discussion

Concern was expressed about the inexorable rise in population in the tropics, although there is surplus land in South America. The question as to what investment is needed to transform agriculture to feed the growing populated remained unanswered. The point was made that old work on cover crops is being repeated i.e. the wheel is still being reinvented – but significantly, in Africa there is little space in the farming systems for cover crops. However, it was suggested that perhaps we need more plantation crops to increase production.

The use of rice straw in the Indo-Gangetic plain illustrates the classic conflict of demands – should it be returned to the soil or burned as fuel instead of paraffin?. Burning any fossil fuel, it was recalled, brings back carbon that had been previously removed from the system. It would be better to grow a crop such as willow for burning in power stations – as a way of recycling the carbon. On the other hand the machinery involved in production also uses fuel. These problems require careful modelling.

It was pointed out that while the importation of organic asparagus from South America brings money to low income groups, still the energy costs are considerable. All types of subsidies ought to be factored into the final cost analysis. On the question of sustainability it was noted that in Northern Nigeria, the Kano close-settled zone farming system has supported sustained intensive agriculture for many years without suffering from land degradation.

“Land shortages have forced many smallholder farmers to cultivate steeplands. Accelerated soil degradation associated with smallholder agriculture in steeplands is often combated by promotion of soil and water (SWC) conservation to control soil loss. Research shows that, on slopes of less than 20%, these can be effective in reducing soil and water loss and in increasing productivity. It is less certain that they work on the steeper slopes now being brought into cultivation. In any case few farmers adopt these technologies. Research in two steepland areas of Honduras examine the rationale behind farmers’ decisions to reject official SWC recommendations.

Qualitative and quantitative research demonstrates that farmers identify erratic rainfall, pests and diseases and a lack of economic resources as greater threats to their livelihoods than soil erosion. Field research on farmed test plots shows the predicament faced by smallholder farmers in terms of significantly reduced maize yields on 65-75% slopes compared to 35-45% slopes. Significantly reduced maize yields from the test plots during El Niño confirms that moisture is more of a limiting factor on productivity than soil erosion. The research also shows that soil erosion may not be as severe as has been reported for steeplands and that differences in soil loss are determined more by infiltration rates rather than by slope per se. Soil erosion rates are highly variable and too small to be easily recognised by farmers, especially when the soil surface is protected by vegetation.

Field trials also show that a widely-promoted technology – live barriers of Vetiver grass (Vetiveria zizanoides) is not effective at reducing soil loss, enhancing productivity on slopes greater than 35%, or protecting hillsides from landslide damage associated with prolonged and intense rainfall. For many farmers, the decision not to adopt SWC technologies is rational. This is especially true where land and labour shortages increase the opportunity cost of establishing and maintaining the technologies.

Conventional SWC initiatives have focussed on controlling soil loss. Farmer-research demonstrates that new approaches to SWC are needed. In Honduras, more successful outcomes have been achieved by a ‘land husbandry’ approach, which includes active farmer participation and better complements farmers’ realities. The approach seeks to combine farmers’ concerns about productivity with conservationists’ concerns about reducing soil erosion. The focus is on improving soil quality for production rather than controlling soil loss”.

Conservation tillage or more specifically, no-tillage, evolved during the latter half of the 20th century, gradually replacing moldboard plowing as the unquestioned "culture" for soil management. This book examines how the change occurred in the United States and Australia. Unlike many social analyses, the text focuses on people rather than the latest statistical technique or regression line. Insights and perspectives gained through the authors' distinguished careers are scattered throughout the book and will enlighten even the most technically oriented reader. The book provides a comparative analysis of no-tillage technology and the subsequent diffusion of numerous innovative techniques using case studies and secondary data. The authors stress that successful conservation tillage systems are farmer managed, that many innovations were initiated by personal dissatisfaction with the status quo, and that social networks were crucial for linking people and sustaining the change through several action-learning sessions. They also help the reader understand the cultural headlock that moldboard plowing had, not only on farmers but also on the larger U.S. and Australian societies. The authors explain the evolution of "plow culture" and its relative importance to settlers in both countries as they sought to create a civilized society and become more productive. Personal pride and community recognition (e.g. plowing contests) were among the reasons "plow culture" became an integral part of agriculture. By explaining the underlying thought process contributing to development of conservation tillage systems, the authors document how the traditional hold was broken so that conservation tillage is now an integral part of agriculture's social and cultural fabric.

After introducing their key propositions (Chapter 1), the authors conceptualize how new tillage systems are social and cultural products (Chapter 2) and then analyze the historical development of "plow culture." The impact of post-World War II change in international markets and national policies for agriculture in both countries are discussed (Chapter 4) as a foundation for building social networks consisting of innovative farmers and various advisors. Chapters 6 and 7 provide case histories illustrating the repetitive action-learning processes that ultimately result in system innovation. Chapter 8 traces the creation of a new culture for cropping over an 8-year period during the 1960s in Kentucky and slightly more than a decade during the 1970s in Queensland, Australia. The authors stress that in both countries the increased adoption of no-tillage was episodic rather than gradual as most traditional adoption models suggest. They also examine major factors affecting the takeoff and subsequent growth of no-tillage and other conservation tillage practices. Policy, market, and institutional factors, as well as environmental and social movements are analyzed in Chapter 9. This provides the basis for discussing how institutions engaged in promoting and assisting system change can be more effective (Chapter 10). The authors conclude (Chapter 11) with a discussion of how the previously unquestioned center-post of farming operations (i.e. the plow and plow culture) has become an anathema to both farmers and an ecologically minded public during the latter portion of the 20^th century.

The authors also stress the importance of biophysical setting as an explicit factor in the social construction of any agricultural system. Soils, slope, weather patterns, and pest cycles are recognized as real-world constraints that condition or limit farmer response. The authors help the reader understand technical advances and adoption issues from the perspective of individual farmers, not as a research study, nor from an institutional or bureaucratic perspective. Farmers are the heroes in this saga. Individual farmers invent and fine-tune not one but numerous conservation tillage systems because of both environmental and economic necessities.

Perhaps the most important contribution of this book is the careful description of what the classic Rogerian model calls the adoption process. As the authors emphasize, this is not some inevitable outcome based on social psychological determinants or economic determinism - it is a fragile process of social construction and re-construction. It is a recursive process as the farmer responds to cycles in weather, market, biological, agribusiness and scientific processes. The driving forces were personal, human forces that created and pushed the new tillage systems. The impetus was emphatically not coming from the agricultural industry, the government, or universities. Furthermore, the authors show that these processes operate at multiple spatial and temporal scales while explaining the change at farm, neighborhood, regional, and national levels. The authors recognize that not all farmers are capable of this invention process due to a lack of resources at individual or social levels. This enables the authors to avoid the "blaming the victim" criticism, and instead focus on the iterative process between individual, social, and biophysical context.

Certainly, the post-World War II development of herbicides was a critical technological advancement that facilitated the implementation of no-tillage and other conservation tillage practices. However, no two farms or farmers are alike. By emphasizing the on-farm testing the authors enable the reader to personalize the tremendous risk faced by these farmer inventors as they confront numerous challenges including insects, rodents, weeds, baked soils, inadequate equipment, drought, wet fields, and community scorn. These case studies document that conservation tillage technology can't simply be taken off the shelf and that those expected to implement the practices must be involved in all aspects of its development. As emphasized by the book's subtitle: "Constructing the New Culture of Agriculture," the authors show how experience and peer pressure govern not only farmer decisions, but also the research agendas of public sector agencies and market strategies of agribusiness.

The authors do a creditable job of explaining how policy influenced conservation tillage adoption throughout the 1980's and 1990's - especially Conservation Reserve Programs, Sodbuster, Swampbuster and Conservation Compliance. The authors tend to identify the Cooperative Extension Service as proponents, while criticizing the Natural Resources Conservation Service as truants in this revolution. Although it is fashionable to poke fun at Washington's ineptness, federal conservation agencies and nonprofit organizations had a huge influence in crafting these policies and will exert a guiding hand in current and future farm bills. Farm bill policies are developed through alliances among executive and congressional branches of government and with input from industry, growers, commodity groups, academia, and non-profit organizations. The National Crop Residue Management Alliance is an example of a marketing campaign developed to promote crop residue management in the early 1990's.

Prepared initially for an "Authors Meet the Critics" session at the 64^th Annual Meeting of the Rural Sociological Society, we were pleased with how Drs. Coughenour and Chamala presented their detailed research and that they put human beings into the landscape of a sociologically based study. They made superb use of historical records, existing research, country comparisons, statistical data and case studies to develop an informative and worthwhile book that can be enjoyed by the student and expert alike. We recommend that people read the book to gain an understanding and explanation of the innovative changes that occurred during the last 50 years of agriculture. Doing so will enable the agricultural community to more effectively incorporate customers into research planning, design, conducting, evaluating, interpreting, and implementing of future ideas. This book will influence research agendas associated with market, urbanization and environmental pressures. Although not a fair criticism, we agreed that in some ways the book ended too soon. Throughout the various chapters, we read about farmers, public agency personnel, and scientists struggling with the different pests that emerged with new tillage systems. We would like to know the author's insight regarding the role that biotechnology and herbicide resistant varieties play in this process. Are the new products (e.g., Roundup-Ready soybeans) just another tool developed in response to farmer need, or do they signify another new culture emerging in agriculture? We anxiously await an answer to this and numerous other questions associated with natural resource management”.

CD-ROM # 22: Training Modules on Conservation Agriculture version 1.0

The purpose of these training modules is to support the promotion of conservation agriculture at community level. The modules provide practical information about the different principles of Conservation Agriculture. The training guide consists of eight different modules; concepts; soil health and fertility; cover crops and crop rotation; tools, machinery and equipment; weed management; pest and disease control; farm management and economics and crop-livestock interaction.

The reported benefits of Conservation Agriculture are: reduced production costs, higher yields, less weed problems and thus reduced herbicide use, reduced water need, higher fertiliser efficiency, less lodging, reduced fuel use, less wear of machinery, savings in time, savings in labour and higher farm profit.

A next version of this CD-ROM will include a module with exercises for learning-by-doing and will allow for rapid consultation of the different modules through interactive menus and cross-references in the text.

On the web: http://www.fao. org/ag/agl/lwdms.stm#cd22.

To order, contact: Jose Benites at: Jose.Benites@fao.org copied to Pilar.Pazos@fao.org

For large orders please contact publications-sales@fao.org

Conservation Agriculture : Case Studies in Latin America and Africa

FAO's Soil Bulletin # 78 (Spanish version now available)

La agricultura de conservatión se caracteriza por la eliminación del disturbio mecánico del suelo, por una cobertura permanente del suelo y por la rotación de los cultivos. Estos tres elementos distinguen la agricultura de conservación de los sistemas agricolas convencionales. El propósito de esta publicación es demostrar como esta agricultura incrementa la producción y al mismo tiempo reduce la erosión y revierte el proceso de disminucion de la fertilidad del suelo; mejora las condiciones de la vida de la población rural y restaura el

ambiente en los paises en desarrollo. Ei estudio se basa en testimonies y experiencias de agricultores y extensionistas en América Latina y en Africa.

To order, contact: Jose Benites at: Jose.Benites@fao.org copied to Pilar.Pazos@fao.org

For large orders please contact publications-sales@fao.org

Report of the International Workshop ‘Conservation Agriculture for Sustainable Wheat Production in Rotation with Cotton in Limited Water Resource Areas’.

The International Workshop ‘Conservation Agriculture for Sustainable Wheat Production in Rotation with Cotton in Limited Water Resource Areas’ was jointly organised by the Tashkent Institute of Irrigation and Agricultural

Mechanisation Engineers (TIIAME) of the Ministry of Agriculture and Water Resources (MAWR), Uzbekistan and the Food and Agriculture Organisation of the United Nations (FAO). The meeting was held in Tashkent, Uzbekistan, in October 13-18, 2002, with a view to bring together farmers, advisers, scientists, private sector and decision makers to share information and experiences, and to encourage further interactions and development. The workshop was a direct follow up of previous workshops in Shortandy/Kazakhstan (1999) and Lahore/Pakistan (2001) and was building on the experiences gathered since those events.

The report of the meeting can be obtained directly from Dr. Alim Pulatov, Director TIIAME alim@freenet.uz

FAO Photo Library on Land Management Systems and Conservation Agriculture

The goal of this photo library is to introduce and illustrate practices of land management systems and conservation agriculture and their benefits. Extension services, agricultural research centres and educational institutes can use the photo library to underline the positive known effects on both inputs and outputs on Conservation Agriculture in a visual way. The photo library is divided into twelve main subjects. All photos are accompanied by information, such as title, country, source and a short description. Web page: http://www.fao.org/ag/agl/agll/consagri/photofile/file/lndex.htm

For more information please contact: Jose Benites at: Jose.Benites@fao.org

Land Degradation Assessment for Dry Lands (LADA) Brochure: Land Degradation in Dry Lands:

The LADA brochure summarises and explains in a well illustrated way the problem of land degradation in dry lands, the objectives of the LADA-project, its approach, work plan and its expected outputs and impacts.

To order please contact Amanda Ball: Amanda.Ball@fao.org

LADA contact: Parviz Koohafkan: Parviz.Koohafkan@fao.org

A Spanish version is available in the AGL online database: http://www.fao.org/agl/agll/docs/lada_s.pdf

More LADA info on: www.fao.org/ag/agl/agll/lada/emailconf.stm

The II World Congress on Conservation Agriculture: Producing in Harmony with Nature

Iguacu Falls, Parana, Brazil-August 11-15, 2003

This second Congress will call upon politicians, international institutions, environmentalists, farmers, and private industry to further support and develop the concept of conservation agriculture. The congress starts from the conviction that only with conservation agriculture techniques we will ensure the continuity of sufficient food production for an expanding population while maintaining environmental quality. Its programme will build on the issues and lessons of the first World Congress which took place in Madrid in 2001. In line with the conference theme, keynotes and delegates will address the development of on-farm, practicable, farmer-originated and led, and scientist supported farming systems that develop towards more natural systems for the optimal use of the natural resources. Further information on the congress can be found on the FEBRADPD web site:

www.febrapdp.org.br

For more information: please contact Dr. Osmar Muzilli: omuzilli@pr.gov.br or Jose Benites Jose.Benites@fao.org

CD-ROM # 18 - Conservation Agriculture

This new CD-ROM contains detailed information and literature about Conservation Agriculture to improve the knowledge base of those interested in this concept of Sustainable agriculture. It will provide technical staff as well as policy- and decision -makers with information and arguments that will help to support promote and introduce Conservation Agriculture.

For more information on such publications both in English and other languages, please contact:

Land and Water (AGLL): jose.benites@fao.org

Mechanization (AGSE): theodor.friedrich@fao.org

Crops (AGPC): thomas.bachmann@fao.org

Animal Production (AGAP): manuel.sanchez@fao.org

or click:

http://www.fao.org/landandwater/lwdms.stmfcd18

The ABLH membership had been individually notified of the proposal. In addition to the Committee, who were unanimously in favour of the proposal after much consideration, there had been 5 endorsements from members and no objections. . . .

It was noted that members would need to be informed of both the decision itself, and any action they need to take. Financial arrangements were discussed and it was noted that as a specialist group within TAA, ABLH might keep control of its funds or get an annual subvention (of perhaps £500) from the TAA central fund – similar to the arrangements for the TAA Award Fund.

It was also noted that DfID had moved from project to programme aid, and that forestry is currently more favoured than agriculture (who eats trees?). Although ODI is still supported by DfID its funds are being cut back. It was felt that specialist groups under TAA would help to keep a higher profile for tropical agriculture.

Other specialist groups proposed are;

· Forestry

· Agricultural Engineering

· Commonwealth Agricultural Society”. . . .

.oOo.

MISC. BITS

Think-pic 5

)

Here’s a problem in rainfed agriculture in seasonally-dry tropical and subtropical lands which won’t easily be sorted out just by genetic modification of crops!

.oOo.

“Improving water and soil quality with

CONSERVATION

BUFFERS

….

Table 1: Conservation buffers come in a rich variety of shapes and sizes …. “

(Title of an article, and a caption, by Lowrance, Dabney and Schultz in J.Soil & Water Cons.(USA,) Mar./Apl. 2002, pp.36A,38A)

ARE THEY TALKING ABOUT US ?

.oOo.

This is the last full issue of ENABLE. Contributions to this TAA website will In future be extracts from earlier issues.

The Editor

PUBLICATION DETAILS: ”ENABLE” IS THE NEWSLETTER OF THE ASSOCIATION FOR BETTER LAND HUSBANDRY, U.K.REGD. CHARITY 1025653. AUTHORS ARE RESPONSIBLE FOR THE VIEWS EXPRESSED IN THEIR PAPERS WHICH ARE NOT NECESSARILY THOSE OF THE ASSOCIATION. THE NEWSLETTER FUNCTIONS AS A FORUM FOR NEWS AND DISCUSSION OF ISSUES RELATED TO PROMOTING BETTER LAND HUSBANDRY, AND WELCOMES CONTRIBUTIONS ESPECIALLY FROM ABLH MEMBERS AND ALSO FROM OTHER INTERESTED PERSONS. CONTRIBUTIONS SHOULD BE SUBMITTED – PREFERABLY BY E-MAIL, OR ON DISKETTE IN MS-WORD FORMAT – TO THE EDITOR: FRANCIS SHAXSON, GREENSBRIDGE, WINTERBORNE KINGSTON, DORSET DT11 9BJ, U.K. / FShaxson@aol.com

Chairman’s opening remarks (Dr John Coulter)

Invited papers

Adverse effects of cultivations on tropical soils,

and successes with no-till farming (Francis Shaxson, ABLH)

Carbon sequestration (Dr David Powlson, Carbon Cycling Programme, Rothamsted Research, Harpenden)

Water for “Tropical Agriculture” – does measurement lead to improved management? (Henry Gunston, lately of the Institute of Hydrology, Wallingford)

Recent developments in FAO’s work on soil management: Conservation Agriculture – combining productivity with resource efficiency and sustainability