Multi-Year Prediction of Rice Yield As Affected by Changing Agro-Climatic Indices in Nawalparasi Using Dssat Crop Model

Abstract

Nawalparasi district is one of the major production domain of rice however, its yield over last 30 years have been majorly affected by anomalies of agro-climatic indices like fluctuating maximum and minimum temperatures, solar radiation and rainfall. Even though, Department of Hydrology and Meteorology is the prime institute to record the historical weather data in Nepal, some major indicators like solar radiation are missing from their data repository. Therefore, NASA Power data of 33 years records (1985-2018) were purposively selected and validated for the study of the multi-year prediction of agroclimatic

scenarios on yield of rice in Nawalparasi district. The trend analysis on grain yields of rice was correlated over the historical records of maximum and minimum temperatures along with rainfall. A positive correlation was found with rainfall with wellformed

regression equations as well as strong coefficient of determination (R² value of 0.71). However, the yield was found to be negatively correlated with the maximum temperature (R² value of -0.56) and minimum temperature (R² value of -0.11). Cropping Systems model CERES-Rice embedded in Decision Support System for Agro-technology Transform (DSSAT) ver 4.7 model was used to study the multi-year prediction of rice yield over the recorded and simulated climatic scenarios. The data set to run the CSMCERES-Rice

model taken from the well predicted and validated crop model Sukkha-5 cultivar of rice and was well used in Terai condition of clay loam soil, resembling the production domain of the project sites. The simulation results using DSSAT model over the 33 years of weather data were found to be very closely agreeing with the observed data of the rice yield recorded from the Ministry of Agriculture and Livestock Development in Nepal. The multi-year prediction of the weather years was also done after following IPCC (2007) scenario using environmental modification section of the DSSAT ver 4.7 models and result showed that the rice yields for few years can only be sustained by using the present crop varieties and urged for the development of climate change ready crop varieties to feed the increasingly growing population. Simulation of the model showed that the rice yield will be decreased by about 62% at the end of 2080s comparing to the standard condition. Agro-climatic indices mainly rainfall was found to be more sensitive for rice production in Central Terai including Nawalparasi district, Nepal. Keywords: Agro-climatic indices, DSSAT 4.7 crop model, Multi-year prediction, Rice yield