Future food, fiber, and fuel demands will not be met by expanding cropland area; continued advances in nutrient use efficiency will moderate increased nutrient demand. With a growing population, dwindling arable land, and an increased demand for biofuels, the world cannot count on an expansion of harvested area to fill the demands of the world's growing population. The use of genetics to improve crop productivity, promote soil conservation and management, and use nutrients efficiently is necessary. The key lies in supporting research and development in these areas. This CAST Issue Paper (IP 51) looks at the background leading to the current situation and addresses the resulting requirements as world food production develops during the next 40 years. The authors use data to analyze factors influencing crop production now and indications of what is to come, and they show how research regarding nutrient use, recovery, and recycling is crucial.