Ecological Sustainability of the Paddy Soil-rice System in Asia

The paddy soil-rice system has efficient nutrient replenishing mechanisms. Basic cations and silica are supplied by irrigation water, while biological fixation works as an inexhaustible source of N in the system, and phosphorus availability is enhanced under anaerobic conditions. This, along with almost perfect resistance to soil erosion, gives the paddy rice system high productivity as well as high sustainability. To cope with an increasing world population, the paddy rice system has to be intensified by developing the infrastructure for irrigation and drainage, and adopting high-input technologies. A tentative conclusion in this paper is that the intensification of paddy rice cultivation is not likely to have as serious an adverse impact on the environment as would be expected from the intensification of upland food production systems.