Modeling rice production in kole lands and its vulnerability to climate change

Abstract

Rice is the most important staple food crop for more than 2/3rd of India’s population, and is the primary source of food for more than three billion people globally. Hence rice production plays a significant role in food security under a changing climate. The Kole lands is a multiple use wetland ecosystem covering an area of 13,632 ha spread over Thrissur and Malappuram districts, and form one of the rice granaries of Kerala. It is a part of the unique Vembanad-Kole wetland ecosystem. The objectives of the study were to develop crop weather relationship for the predominant rice varieties and assess possible changes in yield due to climate change and to study the impact of abiotic factors and farming practices on rice production using simulation model. Daily weather data for the period 1998-2016 were collected from the India Meteorological Department, Thiruvananthapuram. Information on area, production and productivity of rice in Kole lands was collected from Agriculture Statistics Report - Department of Economics and Statistics, Kerala. The weather data from General Circulation Models based on RCP 4.5 and 8.5 were used for the analysis and projections were made up to 2050. Weather cock v.1.5 was used for converting the daily weather data into standard week, month and seasonal formats. The rainfall parameters or indices like seasonal and monthly rainfall, rainy days and high rainfall events were calculated. It is also used to compute PET and Thornthwaite water balances. The crop simulation model DSSAT –developed by IBSNAT was used for studying the impact of climate change on these ecosystems. The monthly rainfall of Kole lands indicates that there was an increase in rainfall during the months of June, July and August as per RCP 4.5 and 8.5. According to RCP 4.5 and 8.5 an increasing trend in number of seasonal rainy days was observed during the monsoon seasons. The maximum amount of potential evapotranspiration was observed during the month of May, whereas the minimum in, November December, and January. The months of January, February, March, April, November and December were found to have no surplus. Whereas water deficit is projected to happen during the month of march. The maximum amount of surplus was found to occur in July and the yearly value shows an increase from the current condition. The area under rice production has shown a declining in Kole lands over a period of 2008 – 2017. Results indicates that the productivity of rice in Kole lands during the first cropping season was 2.08 t/ha. By 2030, the second cropping season was projected to have a yield of 3.124 t/ha. By 2050, the third cropping season would surpass the productivity of first two seasons with productivity of 3.424 t/ha.