Estimating water table contributions to corn and sorghum water use

Shallow water table contribution to supply crop water use may be important in arid and semi-arid regions. Development of predictive equations make it possible for planners to incorporate interaction between water table and root zone into design of irrigation projects. The objectives of this study were to determine the shallow water table contribution to corn and sorghum seasonal and short interval water use with water table variations of 1–2 m in Kooshkak area (Fars province, I.R. of Iran). Two different simple linear equations were devised to predict water table contribution to crop water use for corn and sorghum. The slopes of these equations were similar for both crops, however, the intercept of the equation for sorghum was 1.28 times that for corn. The results also indicated that by lowering water table depth, the reduction in water table contribution for corn may be reduced 22% more than that for sorghum. Furthermore, sorghum water needs may be more effectively supplied by water table at longer irrigation intervals.