Studies on palatability of rice in northern Kyushu: VIII. Nitrogen fertilizer and zeolite application for improving the eating-quality of rice produced on andosol paddy field

This study was carried out to establish cultivation techniques that improve the eating-quality of rice grown in Andosol (AL) paddy fields by the modification of nitrogen fertilizer application and the application of zeolite to supress nitrogen absorption. The rice produced in the AL paddy fields, with a cultivation method that omits the second top-dressing of nitrogen at the panicle formation stage, and zeolite application under standard nitrogen fertilizer application was equally palatable as that produced in Gray Lowland soil (GL) under the same weather conditions, where rice with good palatability is produced under standard nitrogen fertilizer applications. In AL soil, the rice protein content decreased, but the yield did not decrease as compared with that produced under standard nitrogen fertilizer applications. The results obtained lead to the conclusion that the production of highly palatable rice in AL paddy fields is possible by reducing the level of nitrogen absorption. To improve the eating-quality of rice grown in AL paddy fields without reducing the yield, it is recommended that the application of the second top-dressing nitrogen at panicle formation stage be omitted from the standard application method, or that 1kgm^-2 zeolite be applied under the standard fertilizer application method.