Rainfall/moisture and nutrient/fertilizer management options for enhancing productivity and water and nutrient use efficiency in arid/semiarid areas.

Abstract

Insu cient and highly variable precipitation, and frequently low soil fertility are the major biophysical constraints to agricultural productivity in farming systems in the dry areas which account for about 40% of the earth’s surface land area. Such constraints can be mitigated by management interventions. Reduced runo and evaporation can lead to increased crop yields in semiarid zones where land has been shaped into basins to retain rainwater on the eld. Other practices that enhance rain-fed crop production include residual moisture a er harvesting the main crop, local practices to increase the storage of rainwater or snow water; addition of manure and maintenance of crop residues to improve soil structure, to increase water in ltration into the rooting zone of crops and minimize evaporation losses; reduced tillage to conserve water; and improved fertilizer management, based on soil tests, and appropriate rates, timing and placement of nutrients. Soil fertility in intensi ed farming in the semiarid zones can be maintained only through the use of chemical fertilizers combined with the e cient recycling of organic materials, such as crop residues and farm manure, and the adoption of rotations with legumes, pulse crops, and green manures that x nitrogen and improve soil quality. us, an understanding of interaction e ects between soil water and nutrients is crucial for sustainable crop management in semiarid environments. e goal of optimized management is to attain the highest use e ciency of water as well as of nutrients. Using examples from developing and developed regions of the world, this chapter outlines the various factors underpinning e orts to improve crop production in dry areas through improved technologies and highlights constraints associated with adoption of such technologies by farmers.