Conservation Agriculture in the Semi-Arid Tropics: Prospects and Problems

Relatively less attention has been paid on the use of conservation agriculture (CA) in the arid and semi-arid tropics (SAT), although a lot of information is available from humid and sub-humid regions globally. The objective of this review is to focus on the use of CA – its status, problems and prospects in the semi-arid tropical regions with emphasis on Asia and Africa. The information on the use of CA in SAT regions is summarized and put in context with the information available and lessons learnt on the use of CA in relatively vast tracts of land, especially in Brazil, North America, and Australia. Clearly, there are several bottlenecks in the use of CA in the SAT regions of Asia and Africa especially under rainfed agriculture. Among the major constraints to the use of CA in these regions include insufficient amounts of residues due to water shortage and degraded nature of soil resource, competing uses of crop residues, resource poor smallholder farmers, and lack of in-depth research in the SAT regions of Africa and to a lesser extent in Asia. The exception in the implementation of CA is of course the wheat–rice system in south Asia under irrigated conditions. The use of CA in the wheat–rice system of the Indo-Gangetic Plains (IGP) of south Asia has been relatively well researched during the last decade or so. However, in rainfed systems of the drier regions, relatively less attention has been given to develop research strategy to overcome the constraints to the adoption of CA. Examples are given from Brazil, Australia and North America as to how CA has been widely adopted in those regions as well as from Africa where CA is being promoted through active support of donor agencies. Obviously, there is need for strategic long-term research in the SAT regions for exploring the prospects in the face of major constraints faced to the adoption of CA, before CA could be taken to the farmers' door steps.