Characters of untrient cycles and ways for regulating their balance in south Jiangsu Province

The dynamics of farmland untrient cycles and balance in the southern part of Jiangsu Province were analysed based on macro-calculation and field tests. The results show that the main nutrient input is changing from organic fertilizer to inorganic fertilizer;farmland internal cycling is being weakened;Nbalance is changing from deficiency to surplus,P from deficiency to equilibrium, while K is becoming more and more deficient. So dnhancing P and K input and limiting N input as well as increasing the return of organic matter to farmland by mechanization are important ways to regulate farmland nutrient balance in this region.