Irrigation‐Drainage Interaction

This chapter reports approaches to develop crop-water production functions under saline conditions and discusses the factors which affect the production functions. Some examples are given illustrating the interaction between irrigation and drainage. The irrigation-drainage interaction is characterized by the function between applied water and deep percolation. Irrigation and drainage are inseparably linked. Since the major irrigated areas are located in arid and semiarid regions of the world, salinity becomes a significant factor in the interrelationship between irrigation, drainage, and crop production. An array of models is available to simulate the effects of irrigation water salinity, irrigation uniformity, and irrigation scheduling on crop yield and deep percolation. The seasonal model is particularly useful in producing crop-water production functions which account for both salinity and irrigation uniformity for conditions where the water table does not contribute significantly to the water supply of the crop.