Analysis Of Soil Fertility In Shaanxi And Different Measures Increasing Soil Fertility

In order to have a better understanding of soil fertility of the wheat and maize fields in Shaanxi province, the study analyzed the data from the project of soil testing and formulated fertilization and farmer surveys. The results from soil fertility in Shaanxi province were used to build up different measures increasing soil fertility. The main results are listed as follows:In order to provide technical reference for shaanxi wheat production, Weibei plateau, Guanzhong irrigation area and Qin-ba mountain area were selected to determine the properties of the soil and wheat yield and investigate the fertilizer inputs of farmers. The results showed that soil organic matter, available nitrogen, available phosphorus and available potassium in Shaanxi were 14.3 g kg-1,69.0 mg kg-1, 18.5 mg kg-1 and 148.4 mg kg-1; Compared with the 1980 s, the soil fertility were improved, in which soil organic matter increased 33.6%, available nitrogen increased 40.8%, available phosphorus increased 176.1%, available potassium increased 6.8%. The amount of nitrogen fertilizer, phosphorus fertilizer and potassium fertilizer were 183 kg hm-2,109.5 kg hm-2 and 21 kg hm-2 in 2000 s. In order to have a better understanding of soil fertility and fertilizer efficiency of the maize fields in Shaanxi Province after the extension of the technology of soil testing-based formulated fertilization in 2005 ~ 2009 in Weibei Plateau, Guanzhong Irrigation Zone and Qinba Mountainous Area of Shaanxi, collected for analysis were data of 7 416 soil samples and 913 samples of the “3414” fertilizer tests and from sampling surveys of 23 492 households in 75 counties involved in the extension. Results show that the content of soil organic matter, alkali-hydrolyzable nitrogen, available phosphorus and readily available potassium in the maize fields of Shaanxi was 15.2 g kg-1, 72.7 mg kg-1, 19.7 mg kg-1 and 153.9 mg kg-1, respectively, on average. Among the areas surveyed, the Qinba Mountainous Area was the highest in content of soil organic matter and soil alkali-hydrolyzable nitrogen and the Guanzhong Irrigation Zone was in content of soil available phosphorus and soil readily available potassium. In 2000, the inputs of nitrogen(N), phosphorus(P2O5) and potassium(K2O) reached 225.00 kg hm-2, 63.00 kg hm-2and 19.65 kg hm-2, being 114%, 500% and 1 300% higher than that in the 1980 s respectively.Two field experiments located at the Weibei were used to study the effect of different fertilization on the yield and nutrient uptake of wheat/maize and soil fertility in rainfed field. Results showed that fertilizer increased wheat and maize yield, treatment of NP+M had a more pronounced effect. Rational use of chemical fertilizer increased N, P and K uptake in wheat and maize to some extent. NP+M increased by 52.42%, 37.45%, 37.02% and 38.31%, 10.18%, 12.46% in N, P and K uptake in wheat and maize seeds, respectively. Manure decreased soil bulk density and increased soil organic matter. The combined application of N, P and manure made the wheat and maize soil available nitrogen, available phosphorus, available potassium increased by 19.30%, 15.46%, 7.34% and 96.21%, 40.22%, 48.16%, respectively.This research is based on the implement of rainfed farming with straw mulching, plastic film mulching, furrow-ridge tillage, straw and plastic film mulching under furrow-ridge culture, green manure and without mulching to study the changes of spring maize and winter wheat yield, nutrient uptake and soil fertility. The results showed that without mulching winter wheat and spring maize yield was 4882.09 kg hm-2 and 7577.47 kg hm-2, straw mulching increased by 11.98% and 31.75%,plastic film increased by 22.39% and 3.05%, furrow-ridge tillage increased by 16.44% and 0.95%, straw and plastic film mulching under furrow-ridge culture increased by 26.49% and 22.05%, respectively. Straw mulching decreased winter wheat and spring maize soil bulk density by 5.65% and 4.48%, respectively. Straw mulching also can increased soil organic matter. The content of soil organic matter and available potassium in spring maize field under plastic film decreased by 0.07% and 66.89% compare with no mulching.Results show that 3 principal components that could reflect 81% of the original information quantity without losing any original variables were extracted from the initial 8 indices. Within the primary group of principal components OM was the major contributors,while among the secondary group of principal components total potassium was the major ones. Hierarchical cluster analysis of the new indices extracted based on scores of the three principal components revealed the effects of different patterns of long- term fertilization displayed NP+straw mulching is the best fertilizing model.