Study on soil fertility changes and fertilizer recommendation of maize in Dingzhou city,China

In this paper,based on the soil fertility monitoring data in 1986-1994 and 2007-2010 in Dingzhou city,Hebei province,soil fertility changes were made clear.The 3414 field experiments were applied to study contribution rate of soil to crop yield,nutrient supplying capacity of soil and the relations between yield and fertilizer application amounts of nitrogen,phosphorus and potassium on different soil fertility levels.The results indicated that the soil organic matter,available N and P were increased,but available K decreased in 1986-1994;and all of them increased in 2007-2010.Contribution rate of soil to crop yield and nutrient supplying capacity of soil were both declined with time.The regression analysis showed there were significant curve correlations of three-factor square and one-factor square between yield and fertilizer application amounts of nitrogen,phosphorus and potassium on different soil fertility levels.The simulated results of two models were combined to put forward the recommend range of fertilizer amounts of maximum yield and economic optimum yield in this area.