Assessment of Rice Water Requirement by Using CROPWAT Model in Sumbawa Regency, West Nusa Tenggara, Indonesia
Climate change causes pressure on dry land ecosystems, due to limited water availability. The purpose of this research is to assess the water requirement of rainfed rice using Cropwat model in the Unter-Iwes Subdistrict, Sumbawa. The Cropwat 8.0 model with monthly meteorological data input from 2005-2016 in the Sumbawa Regency was used to calculate evapotranspiration, crop water requirements and moisture balance, allowing for adjustment of planting time and evaluation of crop production under dryland conditions. Results showed that the increase in temperature and decreased rainfall can increase the water requirement of rainfed rice plants in the study location. The realization of planting in November (rainy season) requires water at an early stage of plant growth of about 251.9 mm, and can be met from rainfall with a yield reduction risk of 0%. Planting realization conducted in May increase the risk of crop yield reduction, caused by decreased rainfall during the growth period, with a yield reduction of 59.7%.