Irrigated rice production in the Philippines currently shows a declining yield trend for both wet and dry season crops. At the Rice Research Institute Stations the decline was estimated at 1.28% per year and was attributed to environmental degradation, including increased pest and disease pressure, rapid depletion of soil micro-nutrients and changes in soil chemistry brought about by intensive cropping and the increased reliance on low quality irrigation water. The rate of deterioration of the paddy environment was greater than the rate of growth in yield potential of newly developed rice varieties.