Crop water requirement and irrigation scheduling of selected crops using cropwat: A case study of Pattambi region

Abstract

The study entitled “Crop water requirement and irrigation scheduling of selected crops using CROPWAT: A case study of Pattambi region” was taken up to compute the crop water requirement and irrigation schedule of major crops in Pattambi region. The study also focused on analysing whether rain water could meet the evapotranspiration demand of crops. The CROPWAT 8.0 model developed by FAO was used for the determination of crop water requirement and irrigation scheduling. Climatological data including temperature, sunshine hours, wind speed, relative humidity and rainfall were collected from RARS Pattambi for the last 35 years (1983- 2017). The details of major crops of Pattambi region, viz, banana, pepper, pulses, rice (direct sown), rice (transplant) and vegetables were also collected from RARS Pattambi. The required soil, crop and climate data inputs were given to the model and the crop water demand and irrigation schedule for each crop was obtained. The best criteria for scheduling irrigation was also determined. Water requirement for banana, pepper, rice, pepper, rice (transplant), rice (direct sown), pulses and vegetables were found as 1546.2 mm, 327.7 mm, 550.4 mm, 543.3 mm, 351 mm and 564.3 mm respectively for the year 2017. The irrigation requirement for banana, pepper, rice (transplant), rice (direct sown), pulses and vegetables were found as 807.2 mm, 0.0 mm, 309.7 mm, 300.1 mm, 311 mm and 473.2 mm respectively for the same year. The water requirement of crops were found to be dependent on the ET o values while the IR was found to vary with rainfall. The crops should be irrigated with that amount of water which is not provided by rainfall. For both dry crops and wet crops, a lesser rainfall efficiency was found when irrigation was scheduled at fixed interval per stage while a higher rainfall efficiency was found when irrigation was scheduled at critical depletion for dry crops and up to a fixed water depth for rice. The results of the study can be used as a guide for the farmers to plan their irrigation and cropping pattern. Also the results can be extrapolated to the future to analyze the trends in future crop water demands.