gricultural science policy in the United States has profoundly affected the growth and development of agriculture worldwide, not just in the A United States. Over the past 150 years, and especially over the second th half of the 20 Century, public investments in agricultural R&D in the United States grew faster than the value of agricultural production. Public spending on agricultural science grew similarly in other more-developed countries, and c- lectively these efforts, along with private spending, spurred agricultural prod- tivity growth in rich and poor nations alike. The value of this investment is seldom fully appreciated. The resulting p- ductivity improvements have released labor and other resources for alternative uses—in 1900, 29. 2 million Americans (39 percent of the population) were - rectly engaged in farming compared with just 2. 9 million (1. 1 percent) today— while making food and fiber more abundant and cheaper. The benefits are not confined to Americans. U. S. agricultural science has contributed with others to growth in agricultural productivity in many other countries as well as the Un- ed States. The world’s population more than doubled from around 3 billion in 1961 to 6. 54 billion in 2006 (U. S. Census Bureau 2009). Over the same period, production of important grain crops (including maize, wheat and rice) almost trebled, such that global per capita grain production was 18 percent higher in 2006.

Agricultural yields have increased steadily in the last half century, particularly since the Green Revolution. At the same time, inflation-adjusted agricultural commodity prices have been trending downward as increases in supply outpace the growth of demand. Recent severe weather events, biofuel mandates, and a switch toward a more meat-heavy diet in emerging economies have nevertheless boosted commodity prices. Whether this is a temporary jump or the beginning of a longer-term trend is an open question. Agricultural Productivity and Producer Behavior examines the factors contributing to the remarkably steady increase in global yields and assesses whether yield growth can continue. This research also considers whether agricultural productivity growth has been, and will be, associated with significant environmental externalities. Among the topics studied are genetically modified crops; changing climatic factors; farm production responses to government regulations including crop insurance, transport subsidies, and electricity subsidies for groundwater extraction; and the role of specific farm practices such as crop diversification, disease management, and water-saving methods. This research provides new evidence that technological as well as policy choices influence agricultural productivity.

This volume is written primarily for agricultural economists doing research on productivity. It includes discussions of the theoretical underpinnings of productivity measurement as well as the many practical considerations that go into translating this theory into actual measures of aggregated outputs and inputs. The unifying concept of agricultural productivity used across the chapters of this volume is aggregate total factor productivity (TFP) of the sector. The volume also contains detailed analysis of the underlying causes of agricultural productivity growth. Part I (chapters 2-6) examines agricultural productivity in high-income and transition countries. Part II (chapters 7-11) examines agricultural productivity growth and its driving forces in five important agricultural producers in Asia and Latin America. Part III (chapters 12-14) focuses on measuring and identifying constraints to agricultural productivity growth in sub-Saharan Africa. Part IV (chapters 15-16) gives a global perspective on agricultural productivity.