Yield and soil improvement in rainfed crop production

Resources of arable land and irrigation water available in the world are diminishing while the population contin- ues to increase. This situation has contributed to chronic malnutrition and starvation in times of crisis. While the twin problems of overpopulation and unequal distribution of food between rich and poor people are political prob- lems, increasing the supply of food from the existing resources of land and water is a problem that can be ad- dressed by agronomists. It is widely recognised that average farm yields of rainfed crops, even in developed coun- tries, seldom exceed half of the theoretical potential yield if all the rain is used efficiently. It is proposed that this gap between actual and potential grain yield can be effectively addressed using existing technologies that do not destroy soil fertility, and may even improve it. This paper discusses the contributions that agronomists are making and can make in the future to increase the yields of rainfed crops. Agronomic practices that can improve yield and the management of soil resources that will sustain such improvements in the longer term are inter-linked. The in- creasing use and benefits of conservation agriculture, the benefits of rotating crops, especially with legumes, and the possibility of improving crop yields through diagnosing and treating the factors limiting production are dis- cussed.