Agronomy and Horticulture Department


Date of this Version



PNAS, May 21, 2013, vol. 110, no. 21, 8345–8348


Copyright 2013 Sayer and Cassman


In a world of 9.5 billion people, global demand for food, fiber, and biofuels has to be met with minimal possible increases in land, water, fossil fuels, and the minerals used to produce fertilizers (1–4). The problem is debated at three levels: first, that agriculture will not be able to produce enough because it will come up against both biophysical and environmental limits that restrict yields (3, 5, 6); second, that the need to expand and intensify agriculture will destroy the broader environmental values of forests, wetlands, marine systems, and their associated biodiversity (7–9); and third, that there are institutional obstacles to the diffusion and adoption of the innovations that could solve these problems.