CROP COEFFICIENT CALIBRATION OF MAIZE AND INDIAN MUSTARD IN A SEMI-ARID REGION

Crop water requirement is represented by crop evapotranspiration, which is computed as a product of reference evapotranspiration and the corresponding crop coefficient. Moisture depletion in the root zone directly represents crop evapotranspiration. Choice of reference evapotranspiration model has significant influence on crop coefficient calibration. Present study considers the FAO recommended crop coefficients, modified for local climatic and crop parameters. Performance of seven reference evapotranspiration models has been evaluated in estimating crop evapotranspiration. Field experiments on two crops; Maize and Indian mustard, have been carried out. A numerical simulation model has been developed to simulate soil moisture depletion in the root zone. The model uses measured crop and soil parameters, and crop evapotranspiration based on different reference evapotranspiration models. Simulated moisture depletion based on FAO corrected Penman Monteith model (F c P-Mon) closely agrees with the observed moisture depletion for both crops. Study postulates the suitability of F c P-Mon model in crop coefficient calibration for the semiarid region.