We summarize the findings of a recently completed study of the productivity impacts of international crop genetic improvement research in developing countries. Over the period 1960 to 2000, international agricultural research centers, in collaboration with national research programs, contributed to the development of "modern varieties" for many crops. These varieties have contributed to large increases in crop production. Productivity gains, however, have been uneven across crops and regions. Consumers generally benefited from declines in food prices. Farmers benefited only where cost reductions exceeded price reductions.

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Standard-Nutzungsbedingungen:Die Dokumente auf EconStor dürfen zu eigenen wissenschaftlichen Zwecken und zum Privatgebrauch gespeichert und kopiert werden.Sie dürfen die Dokumente nicht für öffentliche oder kommerzielle Zwecke vervielfältigen, öffentlich ausstellen, öffentlich zugänglich machen, vertreiben oder anderweitig nutzen.Sofern die Verfasser die Dokumente unter Open-Content-Lizenzen (insbesondere CC-Lizenzen) zur Verfügung gestellt haben sollten, gelten abweichend von diesen Nutzungsbedingungen die in der dort genannten Lizenz gewährten Nutzungsrechte. Center Discussion Papers are preliminary materials circulated to stimulate discussion and critical comments. References in publications to Discussion Papers should be cleared with the authors to protect the tentative character of these papers. r ABSTRACT This paper reviews studies that have attempted to measure the impact on farmer knowledge, technology adoption, productivity and profits of public sector investments in agricultural extension programs. Forty-seven studies undertaken in 17 countries plus one international study covering 24 developing countries are reviewed. Terms of use: Documents inA number of these studies appeared to be subject to substantial bias because extension measures were endogenous to farmer behavior, i.e., extension contacts were chosen by farmers. Most studies measured positive impacts of extension. Those estimates least subject to bias, i.e.,where extension variables were measured as services supplied to a region, were most consistent in showing impact. Only ten studies report estimated returns to investment in extension. These did report relatively high rates of return and demonstrated that agricultural extension in a number of countries has been a high pay-off public investment.The Economic Impact of Agricultural Extension: A Review Dean Birkhaeuser* Robert E. Evenson* Gershon Feder**The history of economic development shows that few countries have achieved sustained economic growth without first, or simultaneously, developing their agricultural sector.l In most developing countries, agriculture is the most important economic activity providing income, employment, and foreign exchange.Without an efficient agricultural sector, a country is severely constrained in its ability to feed itself or import foreign products for domestic consumption and development. Extension services may be provided by private firms (supplying inputs to farmers and purchasing their products) or by public sector agencies. The case for public sector investment in extension has long been recognized in most countries. The argument is based on the public good nature of many aspects of agricultural knowledge.The potential scope for a pay-off to investment in public sector extension will depend on the effective "gap" between current farm productivity and the potential productivity given the existing "best technology" and "best management" for farms in a particular region. Effective agricultural extension can close both the technology and management gaps. A...

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