During the last half-century, advances in crop production came from expansion in areas irrigated from more intensive application of fertilizers and crop protection chemicals, and from crop varieties that were more responsive to technical inputs and management. Advances in animal production came from genetic improvements and advances in animal nutrition. Differences among developed and developing countries in output per hectare and per worker have widened. If these gaps are to be narrowed agricultural research capacity in developing countries will have to be substantially strengthened.
"Productivity Growth in World Agriculture: Sources and Constraints ."
Journal of Economic Perspectives,