Abstract
To examine whether the prevailing rice farming in Northeast Thailand is sustainable in terms of agro-ecology, the gain and loss of plant nutrients between a paddy plot and its surroundings were studied in the village of Um Mao, Roi Et Province from 1993. The loss of major nutrients, including N, P and K, from the paddies in the form of harvested grains was well balanced by the gain from chemical fertilizers. It was judged that the present farming is fairly compatible with the environment at the current yield level of around 2 ton of unhusked grain per ha. Higher than the present dose of fertilizer would probably result in lower efficiency of application and little increase in the yield. Farmers appear to be well aware of this. For further improvement of the productivity, other means should be sought.
