E. Zaffaroni is Professor and Coordinator of the Agroecosystems
Project at the Federal University of Pelotas, Rio Grande do Sul,
Brazil, and has worked as a consultant to FAO and other
international organizations. Universidade Federal de Pelotas,
Cx. Postal 354, 96010-900, Pelotas, RS Brazil In Latin America
and the Caribbean there are 13.5 million agricultural family
farms involved in subsistence farming. Many of these are small
farms located in areas with poor soils and difficult socio-
economic conditions. These factors have pushed farmers to
exploit their land. The challenge for farmers, and for extension
services, is to improve their productivity without degrading the
natural resource base. It is estimated that millions of hectares
of cultivated land can no longer support agricultural production
adequately (FAO, 1992). This is a result of land being farmed
more intensively, often without proper farming practices, to
meet the demands from a rapidly growing world population for
food, fibre and fuel. New are