Ecological Effects of Different Fertilizations on Red Earth Paddy Soil with K-deficiency

【Objective】 To study the ecological effects of different fertilizations on paddy soil with K-deficiency, a pot-experiment by cropping rice had been conducted for 3.5 years. 【Method】 The experiment was carried out with cropping rice in pot and treated with balanced application of N, P and K fertilizer adding befitting quantity of Si, K and organic manure which close related to rice growth. 【Result】 The rice growing healthily by balanced application of N, P and K fertilizer enhanced internal nutrient use efficiency and the rice yield, which increased up to an extent from 27.7% (NPK treatment) to 51.5% (NPKSi treatment), and produced large amounts of secretion and oxygen from rice root, which increased the quantity of bacteria, the microbial activity, and the content of MBC, MBN, and MBP significantly, in which the content of MBC increased up to a range from 33.9% (NPK) to 47.3% (NPKSi). So the capacity of delivery nutrient in microbial ecosystem was strengthened, and the function of paddy soil ecosystem was enhanced. However, although excessive application of potassium fertilizer (NPhK) for long time promoted the content of available potassium largely in paddy soil, its rice yield wasn not increased markedly compared to application no potassium fertilizer (NP). As a result, microbe community grew unhealthy, and the improvement of quality of paddy soil ecosystem wasn not significant. Accordingly, the treatment of NPKSi had the best ecological effects among all the treatments, followed by NPKM, NPhKM, and NPK. NPhK produced a negative effect. 【Conclusion】 Balanced fertilization of N, P, and K fertilizer is the effective method to improve the quality of paddy soil with K-deficiency, and the treatments of adding Si fertilizer or organic manure based on balanced application of inorganic N, P and K fertilizer have a significant effect.