Recent changes in rice production in rainfed lowland and irrigated ecosystems in Thailand

While Thailand is a major rice exporting country in the world, the yield is low among Asian countries. In order to identify factors determining the changes in rice productivity in the country for the last 45\ua0years (1974–2018), various data on production statistics from the Office of Agricultural Economics were analysed for two key regions of rainfed lowland-based Northeast Thailand and irrigated lowland-based Central Thailand. Rice yield increase in Thailand was slower in the first 16\ua0years to 1989, but more rapid to 2011 followed by a large fluctuation in more recent time, and this pattern reflected in the pattern of rice production in the country. The changes in rice production were partly associated with the changes in irrigation water availability affecting dry season rice area and grain yield, thus increasing total production up to 2011, but thereafter decreasing production. The changes in production were also associated with other factors such as increased fertiliser application rate in early years, proportion of modern high yielding varieties adopted in Central Thailand in early years, and continuous agronomic improvement in Northeast Thailand throughout the whole period. In Northeast Thailand where the largest rice production takes place in the country, the same varieties of high grain quality but rather limited yield potential have dominated since 1974, indicating the importance of grain quality rather than high varietal yield in determining the total rice production in the country. Government policy has appeared to have affected the production, though it is not quantified in the study