Environmentally Sustainable Development Studies and Monographs Series No. 19. Five years have passed since the United Nations Conference on Environment and Development, better known as the Rio Earth Summit. Almost all the countries of the world attended the conference and committed themselves to the policies and programs laid out in Agenda 21, the action plan of the summit. The World Bank and other international agencies have sought to be active partners in implementing the agenda. This report is part of the Bank's current efforts to review the progress made over the past five years and to make plans for improved effectiveness for the future. The paper is divided into two parts. Part I looks at the broad picture, assessing some of the large challenges for the future and outlining thematic principles. Part II provides concise reviews of the majority of the chapters of Agenda 21 and relates them to the standpoint of Bank activities.

Some general charscteristics of farming in a tropical environment; Shifting cultivation systems; Fallow systems; Ley systems; Systems with permanent upland cultivation; Systems with arable irrigation farming; Systems with perennial crops; Grazing systems; General tendences in the development of tropical farm systems.

Power requirements for food production. The Farming Systems Research Programa (FSRP). A focus on water management. The need for improved animal drawn implements. A economic analysis. Optimizing the utilization of machinery.

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.

Food and Agriculture Organization agriculture series: 13