ASSESSMENT OF RICE PRODUCTION UNDER CHANGING CLIMATIC CONDITIONS OF KARAWANG (INDONESIA)

Abstract

Agriculture is vulnerable to unfavorable weather and climate conditions. Climate plays a significant role in agricultural productivity, including rice. The impacts of climate change on rice production are global concerns. Indonesia, where rice is a staple food and strategically important in the agricultural development and economy of the country, is exposed to a great danger, as the country is one of the most vulnerable countries due to climate change. It is reported that decreased rainfall, during critical times of the year and increased rainfall during already -wet times of the year has caused changes in cropping pattern in Indonesia (Boer and Fagih, 2004). Delayed wet season• and a temperature increase beyond 2.5°C is projected to substantially reduce rice yields and incur a loss in farm-level net-revenue of 9 to 25%. Karawang regency is part of West Java-Indonesia which is• the most populated area and the biggest rice producer in Indonesia. Karawang regency is the second largest rice producer in West. Java. Rice production in -Karawang has increased from about 1.077 million tons in 2000 to 1.352 million tons of grain yields in 2009. Long-term records indicate that the present atmospheric concentration of CO2 and the global temperature have increased during the past 100 years. Air temperature and air CO2 concentration will directly affect plant growth. In view of these, it is important to assess the impact of climate change on rice production in Karawang to ensure food sustainability of the country in the future. The. Decision Support System for Agrotechnology Transfer is a widely used decision support system that includes the Cropping System Model (CSM)-CERES Rice. The DSSAT/CERES-Rice model simulates. rice crop growth and development, from either planting or transplanting to harvest maturity and is based on the physiological processes that, describe the response of rice to local soil and weather conditions. To assess rice production under changing 'climatic condition, rice yields. of Karawang, were simulated using the DSSAT rice growth simulation model. A study has. been carried out to assess the production of IR64 rice variety in Karawang using DSSAT/CERES-Rice for summer and rainy season under_future climate scenarios. The study area has adequate irrigation facility and in this simulation nutrient stress was zero, so that we could analyze the impact of changing climatic condition to rice production. Impact of increased_ atmospheric temperature (+1°C, ±2°C and IPCC scenario); changing precipitation amount (+10%, -10% and IPCC scenario); and increased atmospheric CO2 concentration (+50, +100, +200, +300 ppm and doubling concentration) have been carried out for ten years simulation period to analyze the effects of those changing climate conditions on rice productions. The model indicates that yield of rice increases in all elevated atmospheric CO2 concentration scenarios while increased atmospheric temperature has a contrary, effect. For every 1°C increase in temperature, the rice models predict average yield changes of -6.6 and -7.4% for summer and rainy seasons at the current level of CO2 concentration (380 ppm), respectively. But, by doubling CO2 concentration (i.e., 760 ppm) at 25°C, leads to the average increase in yield of about 28.5 and 17.6% for summer and rainy seasons respectively. Further, it is found .that increased CO2 concentration beyond 200 ppm- can nullify the negative effect of higher temperature and optimize the effect of - solar radiation as photosynthesis energy, thereby, increases the yield. There was insignificant trend of impact of future precipitation scenarios on rice yield, since this simulation study was applied in well irrigated area that results in no water stress condition.