Water Balance Analysis for Determination of Time Shift in Rice (Oryza sativa L.)

Rice production in East Java has decreased, which is related to climate change. Uncertain climate results in a shift in planting time. Climate projection scenarios are a solution to see future climatic conditions. One of the analyses used is the water balance. This study aims to study the water balance to determine the rice (Oryza sativa L.) planting time shift based on climate projection scenarios. The research was conducted from March to July 2022 in four districts of East Java. The materials used are average rainfall data and average temperature data for 2000-2020, climate projection data from the CNRM-CM5 and HadGEM2-ES models for 2025-2050, field capacity data, and permanent wilting point data. This study uses a selected sampling technique and the location is chosen as one of the rice production centers in East Java. This research uses exploratory descriptive analysis, statistical descriptive analysis, and the Thornthwaite and Mather method of water balance analysis. The research results show a shift in the planting time of rice plants in four districts in East Java for the years 2025-2050. Malang District experienced a change in the planting time of rice plants of 2 basics, Gresik District experienced a shift in the planting time of rice plants of 2-6 basics, Banyuwangi District experienced a change in planting time of 3-5 basics of rice and Pasuruan District experienced a shift in planting time of rice plants of 1-4 basics.