Crop Coefficient for Potato Crop Evapotranspiration Estimation by Field Water Balance Method in Semi-Arid Region, Maharashtra, India

Crop evapotranspiration (ETc) estimation is essential for many studies such as irrigation system design and management, crop yield simulation, and water resource planning and management. Field studies were conducted at MPKV Rahuri, Maharashtra from 2015 - 2016 and 2016 - 2017 (2 years) in clay soils to determine crop evapotranspiration and crop coefficients (Kc) of the potato crop. The experimental area was cultivated with irrigation applied at 7-days interval. The irrigation scheduling was based on the field water balance approach. The crop evapotranspiration was determined by the field water balance; reference evapotranspiration (ETo) by the Penman-Monteith method and crop coefficients were computed using the standard FAO-56 methodology. The total reference evapotranspiration (ETo) and crop evapotranspiration (ETc) were 226 and 240 mm for the year 2015-2016 and 248 and 250 mm for the year 2016-2017, respectively. The 2-year average reference evapotranspiration was 237 mm and the crop evapotranspiration was 245 mm. The average estimated Kc values for the semi-arid region during the vegetative, tuber development, and maturity stages for potato are 0.55, 1.11, and 1.01, respectively. The calculated values are slightly lower than those suggested by FAO-56 for the vegetative and tuber development stages and higher for the maturity stage of potato. The estimated values of crop coefficients for potato are 11.25% higher than those suggested by FAO-56. However, observed variation between values from the FAO-Kc and Kc calculated by the field water balance is not significant. So, these values can be used for irrigation scheduling of potato in the semi-arid region.