The coordinated regulation of nutrients in intensive paddy field.

In the paddy fields of Southeast China,the non-equilibrium and superfluous inputs of nutrients resulted in several environmental problems such as soil quality degradation,water eutrophication and so on.In this study,the effects of different fertilizer levels on the SPAD values of rice leaves,rice yield,nutrient content and nutrient use efficiency in intensive paddy field were investigated.The results showed that the SPAD values of rice leaves increased with the increasing levels of nitrogen,and the SPAD values showed significant difference in different growth stages as tillering stageheading stagefilling stage.The yield of rice varied significantly under different levels of N and K fertilization,and the optimal N and K fertilizer levels were 225 and 180 kg·hm-2 respectively,but the rice yield did not significantly increase under the application of phosphate fertilizer,which might be due to the higher level of available P in the paddy field.