Spatial Variability Of Soil Nutrients And Evaluation Of Cultivated Land Quality In Farmland Of Shaanxi Province

This study takes the cultivated land in Shaanxi Province as the object,analyzes and evaluates the nutrient status and cultivated land quality of cultivated soil in Shaanxi Province based on the survey data and other relevant data of 5019 samples,and uses the GIS technology and fuzzy evaluation method to obtain the following results.The average content of organic matter and available phosphorus in cultivated soil in Shaanxi Province was 15.6 g/kg and 25.3 mg/kg,respectively.The content of organic matter was low,only reached grade 4,effective phosphorus content was grade 3;soil available potassium average The content is 187 mg/kg,reaching level 2.The average content of total nitrogen is 0.91 g/kg,which is the lowest of the four nutrients.The soil pH was 7.92 and was alkaline.Each nutrient has a very significant spatial correlation.The order of the global Moran's I index is as follows: effective phosphorus>pH>all nitrogen>quick potassium>organic matter,and the spatial aggregation characteristics of all nutrients are obvious;The optimal semi-variance function model of nitrogen and available potassium is an exponential model.The available phosphorus,organic matter and pH are spherical models.The nugget coefficient of soil organic matter and available potassium is between 0.25 and 0.75,with moderate spatial correlation.The nugget coefficients of nitrogen,available phosphorus and pH are all less than 0.25,and the spatial correlation is strong.Both topographical factors such as altitude and slope have an effect on the spatial variability of soil nutrients to some extent.The correlation between altitude and soil nutrients is higher than the correlation between slope and nutrients.(4)The total cultivated land area of Shaanxi Province is 3.87 million hectares,of which the second-level and seventh-level areas account for the largest proportion,reaching 11.86%and 11.91% respectively;the first-level land is the least,with an area of only 235,000 hectares,accounting for 6.08%.Among the three natural areas,the Guanzhong Plain mainly distributes Grade 1 land,Grade 2 land and Grade 3 land.This part of the cultivated land has high nutrient content,low altitude and abundant hydrothermal resources;the cultivated land of each city in Qinba Mountain Area is mainly grade 5-8.The land is mainly because the altitude is relatively high in the plain area,and the imperfect infrastructure limits the production capacity of cultivated land in these areas.However,the quality of cultivated landin the Loess Plateau in northern Shaanxi is the worst,and it is necessary to strengthen infrastructure construction and geo-fertilization work to carry out soil and water conservation.Ecological environment construction.