EFFECT OF CLIMATE VARIABILITY ON RICE PRODUCTION OF NORTHEASTERN THAILAND

Abstract

Rainfed rice cultivation is the key agricultural practice in the Northeast of Thailand. Climate variability is the main cause affecting rice production. The climatic water balance index namely standardized precipitation evapotranspiration index (SPEI) indicates a variety of climate conditions, whether the area is wet (positive) or dry (negative). Our study concerned the effect of climate variability on the production and yield of rice cultivation in five provincial stations in the northwestern of the Northeast which has one of the most
extreme climatic conditions in Thailand. El Nino Southern Oscillation (ENSO) is also related to SPEI and related to rice production and yield. For the study rainfall and meteorological data between 2005 to 2016 were used for analyses. Changes of monthly SPEI over all stations were abrupt compared to ENSO changes which were gradual. During the rice cultivation period, May to September, 1-month SPEI fluctuated from month to month. The summation SPEI values within that 5 months were compared to rice production and yield from each station. All of rice productions increased with SPEI values but only three stations had yields agreeing with SPEI. This shows that the amount of production always relates to wetness but not the yield which depends on other factors such as soil fertility and good management. In marginal paddy fields, cultivation is limited to positive wet conditions. Production may increase depending on the area cultivate, but yields will reduce.