water use efficiency of cotton and wheat crops at various management allowed depletion in lower indus basin

Abstract

This paper deals with contemporary irrigation water management of major crops in Lower Indus Basin of Pakistan. Field experiments were conducted to estimate the optimum WUE (Water Use Efficiency) for various MAD (Management Allowed Depletion) levels including 55, 65 and 75% for cotton crop, and 45, 55 and 65% for wheat crop. The daily actual crop Etca (Evapotranspiration) was observed through gypsum blocks and a drainage Lysimeter. The observed seasonal cotton crops ETca in the experiments were 486, 413, and 397 mm for 55, 65, and 75% MAD levels, respectively. Similarly, wheat crops ETca observed were 363, 359, and 332mm for 45, 55, and 65% MAD levels, respectively. The WUE determined in terms of seed-cotton yield per unit of seasonal water use were 6.0, 6.5, and 5.8kg (ha mm)-1 The corresponding values of WUE for wheat were 14.1, 15.0 and 13.4kg (ha mm)-1. Hence; the highest WUE was achieved with MAD at 65% for cotton and at 55% for wheat.