Synopsis

An overview of agricultural Output and productivity growth is outlined. Three broad historical periods are distinguished. In the first, agriculture improves primarily through biological innovations in the form of new crops and new agricultural practices. In the second, new transport technologies enable agricultural production and trade to expand to a continental and then a global scale. In the third, mechanization, synthetic factor inputs, and new crops, all developed through systematic R&D, push agricultural output and productivity to unprecedented scales. Throughout all three periods labor productivity rises, requiring ever fewer farmers to feed growing populations both at home and abroad. The reduced demand for farmers precedes a related migration from rural to urban areas, labeled urbanization. Progress in agricultural technologies and techniques also progressively decouples the expansion of arable land from population growth and food consumption growth. Initially, this decoupling simply slows down the expansion of agricultural land. Subsequently, international trade effectively transfers the expansion of agricultural land to other countries, limiting further expansion in the industrialized countries. Finally, agricultural productivity increases to such an extent that agricultural land in the industrialized countries can be reconverted to other uses. Thus technological change, combined with saturating demands for food, translates into absolute reductions in agricultural land requirements. Technology begins to spare nature. In contrast with its decreasing land requirements, the overall expansion of agricultural production has more problematic impacts on global water use and global nutrient and geochemical cycles.