What is Conservation Agriculture (CA)

CA is a set of soil management practices that minimize the disruption of the soil's structure, composition and natural biodiversity. Despite high variability in the types of crops grown and specific management regimes, all forms of conservation agriculture share three core principles. These include:

• maintenance of permanent or semi-permanent soil cover;
• minimum soil disturbance through tillage;
• regular crop rotations;

CA also uses or promotes where possible or needed various management practices listed below:

• utilization of green manures/cover crops (GMCC's) to produce the residue cover;
• no burning of crop residues;
• integrated disease and pest management;
• controlled/limited human and mechanical traffic over agricultural soils.

When these CA practices are used by farmers one of the major environmental benefits is reduction in fossil fuel use and greenhouse gas (GHG) emissions.

 

Other Important Definitions

Conservation agriculture is largely the product of the collective efforts of a number of previous agricultural movements, including no-till agriculture, agroforestry, green manures/cover crops, direct planting/seeding, integrated pest management, and conservation tillage among many others. Yet CA is distinct from each of these so-called agricultural packages, even as it draws upon many of their core principles. This is because CA uses many of the available technologies in unison, resulting in something many believe to be much greater than the "sum of its parts."

The following terms are often confused with conservation agriculture:

• No-till (NT)/ Zero till (ZT)
  NT and ZT are technical components used in conservation agriculture that simply involve the absence of tillage/plowing operations on the soil. Crops are planted directly into a seedbed not tilled after harvesting the previous crop. Not everyone utilizing no-till technologies adopts other important components of CA. One major difference is that NT or ZT do not necessarily leave residue mulch. Some recent research data suggests this is vital, since without the residue mulch many of the benefits of CA are lost or decreased in value.

• Conservation tillage/ Minimum tillage/ Reduced tillage
  These are tillage operations that leave at least 30% of the soil surface covered by plant residues in order to increase water infiltration and cut down on soil erosion and runoff. NT is one form of conservation tillage since one goal is to keep the soil permanently covered. But some tillage is usually done. It developed as a management system from the “Dust Bowl” of the 1930’s in the Mid-West areas of the USA.

• Direct planting, direct drilling, plantio direto and siembra directa 
  Are terms used for ZT in other countries like Australia and South America. They use special equipment (e.g. NT drill) to plant seeds directly into crop residues left on the soil surface without preparing a seedbed beforehand.

• Direct seeding
  This term is usually associated with growing a rice crop without producing seedlings that are then transplanted into the main field. However, it is sometimes used to mean ZT.  
• Organic farming
  Organic agriculture does not permit the use of synthetic chemicals to produce plant and animal products, relying instead on the management of soil organic matter (SOM) and biological processes. In some parts of the world, farms must be inspected and certified before their food products can be sold as organic, indicating that no synthetic chemicals were used in producing them.

Unlike organic farming, CA does allow farmers to apply synthetic chemical fertilizers, fungicides, pesticides and herbicides. Many farmers rely on using these to control weed and pest problems, particularly during the early transition years. As soil physical, chemical and biological health improves over time; the use of agrichemicals can be significantly reduced or, in some cases, phased out entirely. 
CA is often used synonymously with ZT that is also believed to require heavy implements and large tractors. However, CA can be used by farmers with large or small holdings as follows:

• Manual systems include practices that build hills (Iroquois Indian “Three Sisters” (Mt. Pleasant, 2006)) or basins (W.African Zai system (Roose et al., 1999)) or use hand held planters (jabbar planters or matracas) or planting sticks (FAO web site).
• Animal traction systems can be as simple as making a furrow for placement of seed and micro-placement of nutrients to planters that can place seed and fertilizer even when residues are present (FAO web site).
• Tractor power systems range from low horsepower, two wheel tractor systems to large, high horsepower models (Baker et al., 2006).

Farmers who do not own tractors can also avail of the tractor powered systems through use of hiring or service providers.