Low input tillage/cropping systems for limited resource areas

Agriculture in limited resource areas is characterized by small farms which an generally too small to adequately support the needs of an average farm family. The farming operation can be described as a low input cropping syst em with the main energy source being manual labor, draught animals and in s ome areas hand tractors. These farming systems are the most important contr ibutor to the national economy of many developing countries. The role of tillage is similar in dryland agricultural systems in both the high input (HICS) and low input cropping systems (LICS), however, wet culti vation or puddling is unique to lowland rice-based systems in low input cro pping systems. Evidence suggest that tillage may result in marginal increas es in crop yield in the short term, however, in the longer term it may be n eutral or give rise to yield decreases associated with soil structural degr adation. On marginal soils, tillage may be required to prepare suitable see dbeds or to release adequate Nitrogen through mineralization, but in the lo nger term, however, tillage reduces soil organic matter content, increases soil erodibility and the emission of greenhouse gases. Tillage in low input cropping systems involves a very large proportion of t he population and any changes: in current practices such as increased mecha nization will have a large social impact such as increased unemployment and increasing feminization of poverty, as mechanization may actually reduce j obs for women. Rapid mechanization is likely to result in failures, but slo wer change, accompanied by measures to provide alternative rural employment , might be beneficial. Agriculture in limited resource areas must produce the food and fiber needs of their community, and its future depends on the development of sustainab le tillage/cropping systems that are suitable for the soil and climatic con ditions. These should be based on sound biophysical principles and meet the needs of and he acceptable to the farming communities. Some of the princip le requirements for a sustainable system includes the maintenance of soil h ealth, an increase in the rain water use efficiency of the system, increase d use of fertilizer and the prevention of erosion. The maintenance of crop residues on the surface is paramount for meeting these requirements, and th e competing use of crop residues must be met from other sources. These requ irements can be met within a zonal tillage system combined with suitable ag roforestry, which will reduce the need for crop residues. It is, however, e ssential that farmers participate in the development of any new technologie s to ensure adoption of the new system. (C) 2001 Elsevier Science B.V. All rights reserved.