Establishment Of Soil Nutrient Supply Capacity Index Of Wheat Field Soil On Dry Land Of Weibei

It has been more than 20 years since last soil survey in China, and the situation of soil fertility in China has greatly changed because of varys that occurred in soil management, crop yields and climate. It is of great significance to study the distribution of various kinds of nutrient elements in Changwu area to establish the soil nutrient supply capacity Index. The soil nutrient supply capacity Index plays a very important role to the produciton of wheat and the effect of NPK and trace elements(S, Cu, Zn, Fe, Mn, B, Mo)on the contents of microelement in wheat seed and yield of wheat in Loess Plateau.1)Nitrogen fertilizer has a significant effect on improving wheat quality and increasing wheat yield, moreover lack of N will significantly decrease the concentration of S, Ca, Fe, Mn, Cu and Zn content in wheat seed; applied P fertilizer will significantly increase the concentration of Mg content of wheat,while adding P will significantly decrease the concentration of Zn; applied K fertilizer has no significant effect on both wheat yield and microelement content.2)A plot trial showed that applied S, Cu and Mn into soil tended to increase the wheat yield and biomass, but the spike number and wheat yield decreased after applying B and Mo to soil. Besides application of N, P and K, addition of S to soil showed no significant effect on of nutrient contents of wheat grain, the application of microelements significantly increased the contents of nutrient elements in grain. Zinc fertilizer increased contents of N, P, K, Fe, Cu and B of wheat seed, Boron fertilizer application promoted the absorption and accumulation of P, K, Zn and Mn in wheat grain; While Molybdenum appling significantly increased contents of Zn in wheat grain and tened to increase Mn and B accumulation. Iron fertilization significantly reduced contents of Mn of wheat grain. B and Mo over dose showed toxic effects on winter wheat. Rational rate and combined application of different elements are the key for effective use of mid- and micro- element fertilizer in crop production.3)100 uniformly distributed wheat plots were selected to collect soil and wheat samples in September 2008 to July 2009, and both nutrient contents of soil sample and wheat grain yields and nutrient contents correspondingly to the soil sample were analyzed in order to evaluate the soil nutrient supply capacity. The results demonstrated that the shortage of nitrogen in soils was more serious than other elements in the study area. Nitrate N and ammonium N were recommaned as the key factors for evaluate the soil N supply capacity instead soil total nitrogen content About 30% of the soil in this area were lack of available P, but available K in soils are in the moderate level in most of the soil samples. The contents of available S, Ca and Mg were in high level, and exchangeable Mg were significantly positively correlated with wheat yields. Shortage of microelement Zn and Fe were more serious than Cu and Mn in soil. Base on above analysis, Soil nutrient supply index for soils in wheat field of Changwu county were established as the guide for soil nutrient management..