Chapter 3
Rural communities actively implementing conservation agriculture
"In the past we relied on natural regeneration to improve our soil fertility, then we relied on fertilizer. Now that the population has increased and the cost of fertilizer has gone up, we have to rely on our own efforts to regenerate our soils."
The traditional slash and burn system has been used for generations in many countries, to clear the land before sowing the crops. It consists of slashing part of the forest vegetation and burning the debris. Depending on population pressures and other factors the cleared plot may be used for cultivation for only one to three years, and may then be left fallow while another plot will be cleared. This system is only sustainable where there is land in abundance.
With high population pressures, however, there is less land available, fallow periods are shorter and the plot will be cultivated for more years. Reduction of the fallow period, biomass burning and over-use of the natural resources lead to a loss of organic matter and plant nutrients, increasing erosion and lower yields.
Farmers have the ability to make development sustainable - to ensure that it meets the needs of the present without compromising the ability of future generations to meet their own needs. Usually their decisions about change are strongly influenced by their assessment of the risks attached to an innovation including its possible side effects. Their seemingly reactionary or conservative attitudes may be in fact an essential caution in weighing the possible benefits and hazards that could follow change.
Where new conservation-effective technologies or practices have met farmer requirements for risk aversion, create no major conflicts and have an assured beneficial effect, adoption has been shown to be very rapid, e.g. zero tillage in the Brazilian cerrado, use of shade trees for coffee production in parts of Costa Rica, agroforestry in Kenya and Nepal.
Farmers have multiple objectives, hence a need for multi-disciplinary analysis of the problems they face in specific situations, and for multi-purpose solutions. But they often do not have contact with people and information that can help them work out appropriate solutions to the problems which they really face, and which are not always those in fashion among policy makers, technicians and scientists (Box 13).
The challenge is for would-be advisers to develop a sense of partnership with farmers, participating with them in defining and solving problems rather than only expecting them to participate in implementing projects prepared from outside.
Farmers have latent skills and enthusiasm, which are tapped when they are involved in doing things that concern and interest them. For instance, experiences with small resource-poor farmers in Kenya, Costa Rica, El Salvador and Honduras show that in cases where conservation-effective farming can increase their cash incomes, they are keen to adapt and adopt such techniques, even if this may lead ultimately to a complete change in farming system (Plate 9).
For example, the Quesungual system (Box 14) offers an alternative land use practice for farmers as land becomes scarcer in this area, due to continued inequality in land distribution and population increases. It has proved to be a sustainable system surviving with minimal damage the El Niño period in 1997 and excessive rainfall after hurricane Mitch in 1998.
Maasai, traditionally herding cattle, are engaging in vegetable growing activities to increase their income and spread the risks
Successful improvement of land husbandry in a catchment depends not just on the motivations, skills and knowledge of individual farmers, but also on actions taken by groups, communities or regions as a whole. Simple extension of the message, even coupled with demonstration, usually will not suffice. Community-based action through local institutions and users' groups will also be required.
The development of common-interest groups around the concepts and practices of conservation agriculture has already served to provide encouragement and mutual support to members as they make the changeover. These groups have become very effective in farmer-to-farmer spread of the beneficial ideas and practical technologies. They have also begun to develop into significant local pressure-groups for improvements in the policy and institutional environment so as for political and legal support to their initiatives.
For example, zero tillage in Brazil is a story of farmer-led technological evolution and integration. Farmers and technicians who adopted this technology have, so far, consistently resolved all the challenges to its sustainability in the humid sub-tropics and humid wet-dry tropics of Brazil, and obtained results in the humid tropics. This successful experience was initiated and supported by the Brazilian Zero Tillage Association for the Tropics, ZTAT (Box 15), which helped to disseminate the technology in the tropical region of the country.
Zero tillage was attractive to farmers for several reasons: lower production costs, a longer period available for planting, a simpler operation to manage, greater drought tolerance, reduced investment and replacement costs for farm machinery and generally higher yields. The farmers themselves have been extremely active in promoting the new technology. The adoption mechanisms are based on the large-scale continuing substitution of conventional tillage by zero tillage technology. The area under zero tillage in Brazil is estimated at over 13 million ha in 1999/2000, about 30 percent of the area of annual summer crops. The tropical region represents one third of Brazil's zero tillage area.
From the farmer's point of view, the main obstacles to adoption of zero tillage were the lack of knowledge, information and technical support. Considerations of erosion losses, lack of research, crop insurance and opinions of agronomists were not as important when deciding whether to adopt zero tillage or not.
A historic moment: this meeting of farmers, technicians, and municipal leaders from Agrolandia, micro-catchment Ribeirao das Pedras, first discussed how to convert traditional animal traction equiment to direct-sowing equipment
The obstacles were overcome through the activities of Clubes Amigos da Terra (Box 16). The operational basis of the CATs is farmer-to-farmer exchanges of experiences on a monthly basis. Organization of promotional events, such as field days and debates, to assist the spread of zero tillage is common during the learning phase (Landers, 2000). CATs also organise on-farm research and pilot projects with the support of other organizations. An important factor for success has been the assistance which medium and large farmers, through individual CATs and ZTAT (now FEBRAPDP, the Brazilian Federation for Direct Planting into Crop Residues), have provided to small farmers wishing to adopt zero tillage. Private sector support and ZTAT integration with farmers was fundamental to the expansion of zero tillage.
Once large farmers have developed the technology, the research and development effort required to adapt the system to small farmers is relatively small. Thanks to a FEBRAPDP-initiated pilot project in south Brazil, where zero tillage by small farmers is well developed, there are more than ten manufacturers specialising in zero tillage machinery for small farmers. Both in south Brazil and in Paraguay, zero tillage systems for small farmers that eliminate the need for herbicides have been developed.
Recently the LandCare movement in South Africa adopted a similar approach as CAT in Brazil, advocating the establishment of local Landcare Groups which would conduct situation analyses, broaden their strategic understanding with a visioning process, then undertake a participatory land use planning, ideally initially at a micro-catchment level (Auerbach, 2000).
Another example is the Association for Better Land Husbandry in Kenya (Box 17). This NGO aims to identify and promote low-cost methods of better land husbandry that effectively combat poverty and improve the livelihood of rural people.
Before introducing conservation agriculture, it may be necessary to eliminate or alleviate some major effects of degradation, such as compacted soil layers, plant nutrient deficiencies or toxicity, heavy weed infestation.
Depending on their depth, compacted layers in the soil may need to be broken by subsoiling. Subsoiling of compacted and degraded soils can bring spectacular effects due to higher water infiltration and result in immediate yield increases of up to 30 percent.
However, subsoiling is a very energy demanding operation. In degraded soils it can easily lead to a recompaction of the soil which could be even more severe than the original compaction. Therefore subsoiling should only be undertaken in combination with other structure building operations and much care should be taken not to compact the loosened soil. Sandy soils are particularly prone to compaction, and subsoiling may have to be repeated after some years even under a zero tillage system.
In case of shallower compaction horizons deep chiselling of the entire plot might be required during the first and possibly, the second year before changing to a true minimum or zero tillage system. Care should be taken to select tools that loosen the soil with a minimum of surface disturbance. Particularly the transport of clods to the soil surface should be avoided.
Biological chiselling, using different species of deep rooting plants, such as pigeon pea (Cajanus cajan) and castor bean (Ricinus communis) to break hardpans may be a cheaper and more sustainable, albeit slower, option as the structuring elements of the "chiselling" remain in the soil in form of root channels and additional organic matter is applied to the soil.
Before converting a field to zero tillage, care should be taken that the soil surface is as smooth (level or sloping) as possible. Plough furrows, tracks of machines and tractors or any other irregularities should be levelled, as this will not be practical any more under zero tillage.
Severe nutrient deficiencies should be corrected by incorporating mineral fertilizers (especially relatively immobile elements such as phosphorus) into the soil in order to encourage deep rooting. Aluminium toxicity, salinity or other severe soil chemical or physical anomalies might require chemical remedies. However, these actions should be well planned and the reclamation operation, defined on a case by case basis, should be carefully implemented.
Weed management is critical for a successful transition. Weed growth must be controlled not only during but also between cropping seasons to prevent multiplication of weed seeds and the unnecessary utilisation of soil moisture. This can be achieved by using cover crops or by chemical weed control.
The need for purchased inputs, especially mineral fertilizers and herbicides, may increase in some cases in the early phase of adoption of conservation agriculture, but only until a higher level of soil fertility and biological activity are established and a new balance between crops and other plants (weeds) and between pests and beneficial organisms is reached.
The long term experience with conservation agriculture shows that in commercial farming operations the need for purchased farm inputs decreases, as the understanding of the systems grows with the management capacity of the farmer (Derpsch, 1997).
On severely degraded soils, it might be necessary to grow heavy crops of green manure and incorporate them deeply into the topsoil during the first year. But this should be only a first step: later, the biomass should be managed without its incorporation into the soil. In this way organic matter can be built up in the soil, which has great influence on the activity and the population of the micro-organisms. Green manure and other vegetation can be used as a soil cover with mechanical methods (knife rollers or in special cases, mowers or choppers) or by desiccation with herbicides.
Within the framework of the Soil Fertility Initiative (SFI), the International Centre for Research in Agroforestry (ICRAF) has been identifying and evaluating options for soil fertility replenishment in East and Southern Africa. Two years after introducing identified options in farmers' fields, 8 700 smallholder farmers in western Kenya had adopted two of them:
The practice of applying Tithonia as a green manure consists of cutting and chopping leaves and soft twigs into small pieces, before the flowering, and then spreading them evenly over the surface and incorporating them into the soil. As applying Tithonia to a maize crop is not profitable, farmers are applying Tithonia to high-value crops such as sukumawiki (Brassica sp.), french beans, tomatoes and napier grass. Profits were substantially increased, ranging from US$91 to US$1 665 per ha, but the practice is very labour intensive, even if Tithonia is now grown on internal and external borders and boundaries, as well as on contour ridges close to the fields, in order to reduce the time required to collect and carry the material into the field.
A Kenyan farmer in front of his Tithonia hedge, which is cut and used to fertilize his sukumawiki crop (Brassica sp.)
[A.J. Bot]
Flowering wild sunflower, Tithonia, now a roadside weed in Kenya and the United Republic of Tanzania, which is used as green manure in western Kenya
[A.J. Bot]
The other practice adopted by farmers is the improved fallow (Box 18). Surveys have indicated that an average of 23-30 percent of the farmers in western Kenya leave their land fallow for a period of three to six months, and some of them up to one or two years. The reasons for leaving land under natural fallow according to farmers, are the availability of land and labour, erratic rainfall and the soil fertility status of the land.
The limitations of these techniques are the nematode problem and the fact that the soil is still being tilled, which is not an improvement of the soil management under tropical conditions. Conservation or zero tillage should be introduced and the residues produced could then be used as soil cover, which would be more effective for the soil fertility and less labour demanding than incorporating them.
Crop rotation, which is an important practice in conservation agriculture, allows the cultivation of more than one crop, so that farmers can spread the risk of fluctuating prices. Also, in addition to the positive effects on soil organic matter and nutrient cycling, rotations can help break disease, weed, and insect-pest cycles (Box 19). When crops are grown in a rotation, they usually do better than when the same crop is grown in the same field year after year. Rotations can also spread labour needs more evenly during the year.
The presence of crop residues on the soil surface require changes in the seeding and planting techniques used by farmers. Cover crops and crop residues can be managed by desiccation with herbicides, or mechanically by means of cutting, crushing or bending the plants.
Any use of herbicides should be with full regard for health and safety of the operator and for the environment (Plate 13). The use of herbicides should be considered only one of the options in an integrated approach to weed and cover crop management. This is especially important in cases where farmers do not yet have experience in the use of chemicals, or lack financial resources to afford them.
Implements have been adapted for resource-poor farmers: a herbicide spray, which can be drawn either manually or by animals
A good alternative for using herbicides is bending and crushing with a knife-roller (Plate 14). This consists of a roller on which knives are mounted transversally and a support, traction and protection structure. When the roller is pulled, the knives bend over and crush or chop off the plants. Part of the plant biomass comes into close contact with the soil, where the interaction with the soil fauna can start. In case of the establishment of subsequent crops, the bending over should be done in the beginning of the reproductive stage, when the seeds are not yet viable. Leguminous species therefore should be managed at the full flowering stage, and cereals and grasses at the milky stage.
The knife-roller bends over or crushes the cover vegetation, preparing the land for the succeeding crop, which will be sown through the residues
[A. Calgari]
For example in Northern Brazil, the traditional shifting cultivation system consists of a two-year cropping period followed by a fallow period of several years. The land is prepared by burning the slashed fallow vegetation. Intensification of land use with continuation of the traditional agricultural practices leads to a decrease of the system's productivity. A prototype chopper encouraged the farmers to change to a conservation agriculture system (Box 20).
Seed drills and planters have been developed that can plant through increased amounts of crop residues and into soil that has not been tilled at all (Plates 15 and 16). The development of this planting and seeding technology as well as the existence of effective mechanical as well as chemical residue management and weed control technologies, make it possible to grow a crop without any tillage. In these systems the cost reduction and erosion control effects of conservation tillage are maximised. These farming practices are called zero tillage or no-tillage systems. Zero tillage is the most advanced form of conservation agriculture, in which only a narrow slot is opened in the soil for the seeds.
Simple seed drill, which can cope well with the enormous amount of crop residues left in the field
First introduction of an animal-drawn direct seeder in a Maasai village in northern Tanzania
In many societies animals have cultural roles (e.g. their use in rituals or as part of bride-prices), in addition to being a source of food and revenue. An important source of traction for many resource-poor farmers is animal draft power, and animals can also be a source of manure and a method of value-adding and use of crops and crop by-products. Integration of cropping systems with animal production systems is therefore essential for sustainable rural livelihoods (Box 21).
In almost all farming systems, residue management is a critical issue as residues are used for different purpose: fodder, conservation practices, energy source, elaboration of handicrafts. But the most important use in terms of interaction with soil cover is the use of residues as fodder for livestock during the dry period. One prerequisite for adoption of conservation agriculture practices, if residues are to be used for both purposes (conservation, fodder), is that the quantity produced by the system is enough for both objectives (Choto and Saín, 1993). This may be achieved by increasing the production of crop residues through crop selection (Box 22) or crop rotation. For example, crop rotation systems may produce large amounts of residue (14 t/ha per year dry matter) under direct seeding and accumulate about 11 t/ha; in comparison, accumulation may only be 6.5 t/ha per year under conventional agriculture with monoculture systems (Bayer, 1996). Another solution may be to improve crop residue management (Box 23, Plate 18).
Livestock is not only a competitor for crop residues use. It can play a major role in soil fertility improvement if it is integrated into the farming system and well managed (Box 24). However, in cases where plant nutrient outflows exceed inflows, the system can subsequently revert towards its former condition. Livestock management, by partial confinement for example, must be considered as a part of the sustainable development of crop production and can even help increase livestock production and food security.
Stripping maize to separate palatable and non-palatable parts to be used respectively for animal fodder and soil improvement
Drawings explaining box baling of maize stover
