Variability of cereal yields: Sources of change and implications for agricultural research and policy

Abstract

Many countries have achieved impressive rates of growth in national foodgrain production in recent years. Much of this growth can be attributed to new technologies—especially improved varieties—and the increased use of irrigation and fertilizers. As agricultural output has grown, however, so apparently has its variability, and this presents other problems and concerns that need to be addressed by the agricultural research and policy-making community. This article reviews available evidence on patterns of variability in world cereal production and how these patterns have changed in recent years. The biological, climatic and economic factors underlying yield variability and its changes are discussed and implications sought for both agricultural research and policy.