The semi-arid zones of the world are fragile ecosystems which are being sub stantially modified by the activities of mankind. Increasing human populations have resulted in greater demands on semi-arid zones for providing human susten ance and the possibility that this may enhance desertification is a grave concern. These zones are harsh habitats for humans. The famines that resulted from drought during the late 1960's and the 1970's in the African Sahel illustrated the unreliability of present agricultural systems in this zone. Large fluctuations in ag ricultural production have occurred in semi-arid zones of Australia, North Ameri ca, and the Soviet Union due to periodic droughts, even though considerable ag ricultural technology has been devoted to agricultural development in these zones. The challenge to mankind is to manage these different semi-arid zones so that pro ductivity is increased and stabilized, and environmental deterioration is decreased. Irrigation can be used to increase and stabilize agricultural production in semi-arid zones as discussed in Volume 5 of this series, Arid Zone Irrigation. The present volume, Agriculture in Semi-Arid Environments, focuses on dryland farming in semi-arid zones, and is relevant to the large areas of the world where rainfall is limiting and where water is not available for irrigation. This volume is designed to assist agricultural development in these areas and consists of reviews and analyses of available information by scientists working in Africa, Australia, and at the U ni versity of California.

"The assessment builds on the work of the Livestock, Environment and Development (LEAD) Initiative"--Pref.

Technological constraints and opportunities in relation to class of livestock and production objectives; Trhe influence of socioeconomic factors on the availability and utilization of crop residues as animal feeds; Crop residues in Tropical Africa: trends in supply, demand and use; Cowpea and its improvement: key to sustainable mixed crop/livestock farming systems in West Africa; Dynamics of feed resources in mixed farming systems in Southeast, South Asia; West/Central Asia-North Africaand Latin America; Crop residues as a strategic resource in mixed farming systems; Alternatives to crop residues as feed resource in mixed farming systems; Alternatives to crop residues for soil amendment; Crop residues for feeding animals in Asia: technology development and adoption in crop/livestock systems; The national perspective: a synthesis of country reports presented at the Workshop.

Informed livestock sector policy development and priority setting is heavily dependent on a good understanding of livestock production systems. In a collaborative effort between the Food and Agriculture Organization and the International Livestock Research Institute, stock has been taken of where we have come from in agricultural systems classification and mapping; the current state of the art; and the directions in which research and data collection efforts need to take in the future. The book also addresses issues relating to the intensity and scale of production, moving from what is done to how it is done. The intensification of production is an area of particular importance, for it is in the intensive systems that changes are occurring most rapidly and where most information is needed on the implications that intensification of production may have for livelihoods, poverty alleviation, animal diseases, public health and environmental outcomes. A series of case studies is provided, linking livestock production systems to rural livelihoods and poverty and examples of the application of livestock production system maps are drawn from livestock production, now and in the future; livestock's impact on the global environment; animal and public health; and livestock and livelihoods. This book provides a formal reference to Version 5 of the global livestock production systems map, and to revised estimates of the numbers of rural poor livestock keepers, by country and livestock production system.

Reviews past trends, summarizes major constraints to income growth, food security, poverty alleviation, and environmental sustainability, and identifies future research and development strategies and priorities for the semi-arid tropics. Focuses on sub-Saharan Africa and South Asia.