DEPLETION OF PLANT-AVAILABLE SILICON IN SOILS - A POSSIBLE CAUSE OF DECLINING RICE YIELDS

The phenomenon of yield decline in different rice ecosystems from many parts of the world has been reported to be associated with decreases in the effective nitrogen (N) supply from soil. However, many reports in the literature suggest that silicon (Si) is an agronomically essent ial element for sustainable rice production. Depletion of plant-availa ble Si in soils where rice is grown could be a possible limiting facto r contributing to declining yields. In order to address this problem o f yield decline or stagnation, it seems necessary to survey Si status of soils and rice grown in different ecosystems throughout the world a nd develop region-specific integrated nutrient management systems that include the element Si.