General irrigation efficiency for field water management

Abstract On-farm water management systems are traditionally evaluated using a set of performance indices which are inconvenient for evaluation and comparison. We propose a general efficiency ( E g ) which is defined as the ratio of crop transpiration to the sum of the volume of applied water and the volume of deficit. E g combines the characteristics of traditionally used irrigation efficiencies: application efficiency ( E a ), storage efficiency ( E s ) and the Christiansen's coefficient of uniformity ( U c ). Thus, it is possible to compare the performance of different water application systems and/or design and management scenarios using a single index. The relationships of E g vs. E a , E s and U c are also presented using a transpiration fraction (α) which is defined as the ratio of transpiration to evapotranspiration.