INFLUENCE OF CHANGING TILLAGE PRACTICES ON CROP PRODUCTION

The most efficient and practical way of protecting the soil against wi nd and water erosion is with surface and anchored crop residues. The r ate and extent of crop establishment is not adversely affected by cons ervation tillage provided shallow seeding is used and adequate seed-to -soil contact is achieved. Soil water conservation can be enhanced wit h conservation tillage systems and the amount conserved is directly in fluenced by the type and amount of crop residues present and the agro- ecological zone. Crop residue decomposition is 1.5x slower on the surf ace than when buried and the rate of decomposition can be explained al most entirely by the location and nitrogen content of the residues and growing degree days. Grain yield can be improved with conservation ti llage and is directly related to the amount of extra water conserved, regardless of the crop. Crop establishment, which is critical in forag e production, can be improved with conservation tillage. Removing fora ge stands with herbicides as opposed to tillage favoured subsequent cr ops. Further research is required on the manipulation of stubble heigh t and row spacing to enhance water conservation and to determine the i mpact of such changes on crop growth and development, weeds and plant diseases. There is need to develop crop-specific conservation producti on practices for each agroecological zone.