Difference Of Soil Fertility And Nitrogen Supply Capacity In Different Counties Of Hanzhong

Hanzhong region is an important grain and oil production area in Shaanxi province,and it is also one of water source area of middle route south-to-north water transferring project in Our country.The appropriate application of nitrogen fertilizer according to soil nitrogen supply capacity is one of the ways to improve the utilization efficiency of nitrogen fertilizer,increase grain yield and reduce the risk of environmental pollution.In order to understand the representative soil fertility and nitrogen supply ability of different counties in Hanzhong,Shaanxi Province,12 0-20cm farmland cultivated soil with representative and different fertility differences in Hanzhong of Shaanxi province was used as the test soil sample,and on the basis of analyzing the difference of soil fertility,different biological culture and chemical methods were used to study the nitrogen supply capacity of representative soils in different counties of Hanzhong.The main findings obtained were as follows:?1?The range of organic matter content varies between 20.5⁴4.7g·kg^-1,and the soil total nitrogen range is between 1.31².53 g·kg^-1,with the highest Chenggu County and the lowest Mian County.The mineral nitrogen range is 6.61²6.79mg·kg^-1and the average16.2mg·kg-¹.The variation range of soil effective phosphorus was between 9.59⁹7.96mg·kg^-1,and the average content was 27.55mg·kg^-1.The range of soil pH varies in5.58⁷.78,with an average of 6.21.Soil cation Exchange?CEC?in 10.76²4.1cmol/kg,the average value of 18.45cmol/kg,the ability to maintain cation nutrients in each soil sample is above medium.The content of soil sample CaCO₃ was in the first grade of the classification standard of nutrient content,and the average content was 0.2%.Most of the soil texture is loam,and a few are clay.The range of variation coefficients of each index is7.26%⁸4.5%,the largest coefficient of variation is soil effective phosphorus,and the pH coefficient of variation belongs to weak variation.?2?Compared with the NH₄⁺-N content in Submerged culture for 1 week in different counties and the method of Airlifted culture for 2 weeks,the amount of NH₄+-N(17.84?10.19?g·g^-1)in Submerged culture was significantly lower than the amount of NH₃^--N(33.04?11.49?g·g^-1)in Airlifted culture for 2 weeks.The ammonium nitrogen content of mineralization in Submerged culture for 1 week was from large to small in order:Hantai District>Mian County>Yang County>Nanzheng District>Chenggu County.The content of nitrate nitrogen in Airlifted culture for 2 weeks in different counties soil was from large to small in order:Chenggu County>Yang County>Nanzheng District>Hantai District.?3?According to the results of nitrogen extraction from chemical leaching in different counties,the correlation between soil organic matter and total nitrogen was very significant,the correlation coefficient was 0.929,and the correlation degree was high.Mineralized nitrogen is more closely correlated with total nitrogen.The results obtained from KCl reflux boiling were significantly correlated with 1 weeks of ammonium nitrogen in flooded culture at 0.05 level,and the correlation coefficient was 0.643.The soil nitrogen value obtained by acidic potassium permanganate was the size of different counties in Hanzhong:Nanzheng District>Yang County>Hantai District=Chenggu County>Mian County.