About
Conservation
Agriculture
Introduction to CA: Video
Conservation agriculture (CA) aims to achieve sustainable and profitable agriculture and subsequently aimes at improved livelihoods of farmers through the application of the three CA principles: minimal soil disturbance, permanent soil cover and crop rotations. CA holds tremendous potential for all sizes of farms and agro-ecological systems, but its adoption is perhaps most urgently required by smallholder farmers, especially those facing acute labour shortages. It is a way to combine profitable agricultural production with environmental concerns and sustainability and it has been proven to work in a variety of agroecological zones and farming systems. It is been perceived by practitioners as a valid tool for Sustainable Land Management (SLM).
It is because of this promise that FAO is actively involved in promoting CA, especially in developing and emerging economies. CA can only work optimally if the different technical areas are considered simultaneously in an integrated way. Therefore staff from several Divisions of FAO took the initiative to create an informal workgroup consisting of members from the Plant Production and Protection Division (AGP), the Land and Water Division (NRL), and Rural Infrastructure and Agro-Industries Division (AGS). It is understood that the multidisciplinary nature of CA will always require the rich mix of expertise available to FAO as it works to promote the CA concept worldwide.
CA Principles
Conservation agriculture systems utilize soils for the production of crops with the aim of reducing excessive mixing of the soil and maintaining crop residues on the soil surface in order to minimize damage to the environment.
By doing this CA will:
- Provide and maintain an optimum environment of the root-zone to maximum possible depth. Roots are able to function effectively and without restrictions to capture high amounts of plant nutrients and water.
- Ensure that water enters the soil so that (a) plants never, or for the shortest time possible, suffer water stress that will limit the expression of their potential growth; and so that (b) residual water passes down to groundwater and stream flow, not over the surface as runoff.
- Favour beneficial biological activity in the soil in order to (a) maintain and rebuild soil architecture; (b) compete with potential in-soil pathogens; (c) contribute to soil organic matter and various grades of humus; (d) contribute to capture, retention, chelation and slow release of plant nutrients.
- Avoid physical or chemical damage to roots that disrupts their effective functioning.
Direct seeding or planting
Direct seeding involves growing crops without mechanical seedbed preparation and with minimal soil disturbance since the harvest of the previous crop. The term direct seeding is understood in CA systems as synonymous with no-till farming, zero tillage, no-tillage, direct drilling, etc. Planting refers to the precise placing of large seeds (maize and beans for example); whereas seeding usually refers to a continuous flow of seed as in the case of small cereals (wheat and barley for example). The equipment penetrates the soil cover, opens a seeding slot and places the seed into that slot. The size of the seed slot and the associated movement of soil are to be kept at the absolute minimum possible. Ideally the seed slot is completely covered by mulch again after seeding and no loose soil should be visible on the surface.
Land preparation for seeding or planting under no-tillage involves slashing or rolling the weeds, previous crop residues or cover crops; or spraying herbicides for weed control, and seeding directly through the mulch. Crop residues are retained either completely or to a suitable amount to guarantee the complete soil cover, and fertilizer and amendments are either broadcast on the soil surface or applied during seeding.
Permanent soil cover
A permanent soil cover is important to: protect the soil against the deleterious effects of exposure to rain and sun; to provide the micro and macro organisms in the soil with a constant supply of "food"; and alter the microclimate in the soil for optimal growth and development of soil organisms, including plant roots.
Crop rotation
The rotation of crops is not only necessary to offer a diverse "diet" to the soil micro organisms, but as they root at different soil depths, they are capable of exploring different soil layers for nutrients. Nutrients that have been leached to deeper layers and that are no longer available for the commercial crop, can be "recycled" by the crops in rotation. This way the rotation crops function as biological pumps. Furthermore, a diversity of crops in rotation leads to a diverse soil flora and fauna, as the roots excrete different organic substances that attract different types of bacteria and fungi, which in turn, play an important role in the transformation of these substances into plant available nutrients. Crop rotation also has an important phytosanitary function as it prevents the carry over of crop-specific pests and diseases from one crop to the next via crop residues
CA Benefits
To be widely adopted, all new technology needs to have benefits and advantages that attract a broad group of farmers who understand the differences between what they are doing and what they need. In the case of conservation agriculture these benefits can be grouped as:
Economic benefits
Three major economic benefits can result from CA adoption:
- Time saving and thus reduction in labour requirement.
- Reduction of costs, e.g. fuel, machinery operating costs and maintenance, as well as a reduced labour cost.
- Higher efficiency in the sense of more output for a lower input.
The positive impact of conservation agriculture on the distribution of labour during the production cycle and, even more important, the reduction in labour requirement are the main reasons for farmers in Latin America to adopt conservation agriculture, especially for farmers who rely fully on family labour.
Agronomic benefits
Adopting conservation agriculture leads to improvement of soil productivity:
- Organic matter increase.
- In-soil water conservation.
- Improvement of soil structure, and thus rooting zone.
The constant addition of crop residues leads to an increase in the organic matter content of the soil. In the beginning this is limited to the top layer of the soil, but with time this will extend to deeper soil layers. Organic matter plays an important role in the soil: fertilizer use efficiency, water holding capacity, soil aggregation, rooting environment and nutrient retention, all depend on organic matter.
Environmental benefits:
- Reduction in soil erosion, and thus of road, dam and hydroelectric power plant maintenance costs.
- Improvement of water quality.
- Improvement of air quality.
- Biodiversity increase.
- Carbon sequestration.
Residues on the soil surface reduce the splash-effect of the raindrops, and once the energy of the raindrops has dissipated the drops proceed to the soil without any harmful effect. This results in higher infiltration and reduced runoff, leading to less erosion. The residues also form a physical barrier that reduces the speed of water and wind over the surface. Reduction of wind speed reduces evaporation of soil moisture.
Soil erosion is reduced close to the regeneration rate of the soil or even adding to the system due to the accumulation of organic matter. Soil erosion fills surface water reservoirs with sediment, reducing water storage capacity. Sediment in surface water increases wear and tear in hydroelectric installations and pumping devices, which result in higher maintenance costs and necessitates earlier replacement.
More water infiltrates into the soil with conservation agriculture rather than running off the soil surface. Streams are then fed more by subsurface flow than by surface runoff. Thus, surface water is cleaner and more closely resembles groundwater in conservation agriculture than in areas where intensive tillage and accompanying erosion and runoff predominate. Greater infiltration should reduce flooding, by causing more water storage in soil and slow release to streams. Infiltration also recharges groundwater, and thus increasing well supplies and revitalizing dried up springs.
Sediment and dissolved organic matter in surface water must be removed from drinking water supplies. Less sediment loss and less soil particles in suspension, lead to a reduced cost for water treatment.
One aspect of conventional agriculture is its ability to change the landscape. The destruction of the vegetative cover affects the plants, animals and micro-organisms. Some few profit from the change and turn into pests. However, most organisms are negatively affected and either they disappear completely or their numbers are drastically reduced. With the conservation of soil cover in conservation agriculture a habitat is created for a number of species that feed on pests, which in turn attracts more insects, birds and other animals. The rotation of crops and cover crops restrains the loss of genetic biodiversity, which is favoured with mono-cropping.
Systems, based on high crop residue addition and no tillage, accumulate more carbon in the soil, compared to the loss into the atmosphere resulting from plough-based tillage. During the first years of implementing conservation agriculture the organic matter content of the soil is increased through the decomposition of roots and the contribution of vegetative residues on the surface. This organic material is decomposed slowly, and much of it is incorporated into the soil profile, thus the liberation of carbon to the atmosphere also occurs slowly. In the total balance, carbon is sequestered in the soil, and turns the soil into a net sink of carbon. This could have profound consequences in the fight to reduce green house gas emissions into the atmosphere and thereby help to forestall the calamitous impacts of global warming.
CA Adoption
In order to facilitate the change in production system towards conservation agriculture, it is important to understand why farmers think that soil tillage is such an important part of their system.
Soil is tilled in order to break-up the soil after harvest of the previous crop, to eliminate weeds and to prepare the seedbed for the next crop. Farmers perceive it as being important and besides that they feel comfortable with the technology, they know how to manage the technology and they know that tillage activities render good crop yields.
To start with conservation agriculture requires:
- A change in crop management system.
- Technology (a machine or tool) that can manage the crop residues or cover crops.
- Consideration of the soil as a biological and self-sustaining productive system.
- Adoption of a new way of thinking as far as weed management, crop production and livestock / cropping interactions are concerned.
How does a farmer start conservation agriculture?
- Start with composure and concentrate on achievable objectives.
- In order to gain experience, start on a small part of the farm (say 10%).
- Initiate in an area where there is enough cover and use equipment designed to do the job (Machinery, tools and equipment).
- In the case of herbicide use, take time to learn to identify and use herbicides correctly. This includes understanding the calibration of the herbicide applicator.
- Talk to other farmers who are practising conservation agriculture and learn from their experiences and mistakes.
Before starting with conservation agriculture one very important aspect is to plan a good crop rotation. As CA is based on soil life, soils have to be brought up to a condition where life can develop. Physical and chemical soil limitations, such as: compaction; drainage; pH; P and K levels, should be corrected before starting CA. This is especially true in highly degraded or depleted soils where some sort of amelioration investment might be necessary to rehabilitate them. The required actions might include: subsoiling to remove compaction; levelling; liming; use of green manure and synthetic fertilizer to correct extreme nutrient deficiencies. Soils under CA generally improve with time. This means the rate of degradation and erosion is less than the rate of soil build-up. For this reason even highly degraded soils should improve and become productive under CA. A good example is the Brazilian Cerrados, which were considered degraded land unsuitable for farming and which have been converted by CA into a highly productive area.
In the initial years, the focus of conservation agriculture will concentrate on weed control; management of crop and cover crop residues; and monitoring pest and disease incidence. A farmer should be prepared for new habits and timetables.
Conservation agriculture is based on restoring naturally occurring processes and therefore needs a conversion period before the CA system is established and the natural balances are restored. It is advisable that farmers new to CA consult with practitioners to share experiences and set realistic expectations. New CA farmers will require an initial period to gain experience with the innovation. A lot of information will be needed on the use and adjustment of tools and implements. The Brazilian idea of "planter clinics" is very useful for farmers to learn not only about the tools and implements, but also the time needed for conversion to the new system, crop yields during and after the conversion period, labour and time requirements in agricultural activities before and after the change. The experiences of farmers who have been implementing conservation agriculture for a longer time can give indications to new farmers on which key practices generate success and what mistakes to avoid. The formation of Farmer Field Schools is another group action concept that has been successful in many countries.
Frequent questions
1- Is Conservation Agriculture only applicable in certain areas or under certain agro-environmental conditions?
2- Is CA adaptable to different crops? and it's compatible with Livestock schemes?
3- Is CA compatible wtih Agro-ecology approach and principles?
4- Is CA a way to contribute to reduce climate change and to deal with the food security threats?
5- Which is the minimal farm scale needed to adopt CA? Which are the inputs that should be considered?
6-What do I have to know in connection with CA to start its adoption in my farm?
CA TESTIMONIALS
"Afetr CA implementation, we observed a reduction of costs, e.g. fuel, machinery operating costs and maintenance, as well as a reduced labour cost".
Florencia / Agronomist / Argentine
"In regions like ours, CA has allow us to increase orgenic matter content and in-soil wqter levels, as well as to improve soil structure reducing erosion"
Malou/ Farmer / Zimbabwe