Reduction of Phosphate Application in Paddy Rice Cultivation for More Sustainable and Environmentally Sound Agriculture

Proceedings of Shinshu University International Symposium 2007 “Sustainable Agriculture and Environment:Asian Network”
Heavy application of phosphate （P2O5） in paddy rice production has been continued since 1960s in Japan. Although yield was increased and stabilized during that period, recent environmental concerns require minimization of P2O5 application. Six-year experiment on the effect of reduced P2O5 application on growth and yield of paddy rice was carried out in Andosols area, where heavy P2O5 application had been continued. The experiment showed that growth and yield were not significantly influenced by reduced P2O5 application and that reduction by 25-50% compared to the present recommended application amount was safely practicable. Input and loss of available P2O5 in the soil was estimated to balance when P2O5 application is 4.6 kg/10 a. Since available P2O5 has been accumulated in the soil, drastic reduction of P2O5 application over the long term is possible without causing significant decline in yield and its stability by making most of the accumulated P2O5 stock.
Article
信州大学農学部紀要. 44(1-2): 53-56 (2008)