Spatial Variability Of Soil Nutrients And Evaluation Of Quality Grade In Vegetable Soils In Feidong County

With the continous development of the market economy,the vegetable industry has gradually become a pillar industry in agricultural production.The concepts of green vegetables,pollution-free vegetables and organic vegetables have become hot spots,and the quality of vegetables is also getting more and more attention.In recent years,because lack of scientific management of vegetable growers,the decline in the production capacity of vegetable land,and the blind fertilization driven by economic interests,a series of problems such as soil nutrient imbalance and soil acidification in vegetable fields have appeared frequently.Studying and analyzing the quality of vegetable arable land can provide a basis for guiding the production management of vegetable land,improving the yield and quality of local vegetables,and obtaining high-quality,high-yield vegetable products.The vegetable land of Feidong County in Hefei is used as the research area in this study,which is based on GIS and geostatistics to analyze the spatial variability of soil organic matter,available phosphorus,available potassium,alkali nitrogen,available sulfur and pH in the study area.And based on its own vegetable land's characteristics,a hierarchical model and a membership function model for the quality evaluation of vegetable land in Feidong County were established,and the quality evaluation of vegetable cultivated land was carried out.The main conclusions obtained are as follows:(1)The soil organic matter content of vegetable soil in Feidong County is 7.19-44.lOg/kg,the average content is 20.06g/kg,which is moderate;the effective phosphorus content is 1.40-346.95mg/kg,and the average content is 87.08mg/Kg,is a rich level.The available potassium content ranges from 30.42 to 547.00 mg/kg,and the average content is 183.61 mg/kg,which is a relatively high level.The effective sulfur content ranges from 11.62 mg/kg to 327.46 mg/kg,and the average content is 75.16 mg/kg,which is a rich level.The alkali nitrogen content ranges from 30.27 to 273.17 mg/kg,and the average content is 104.99 mg/kg,which is a medium level;the pH value is between 3.55 and 7.90,and the average value is 5.32,which is weakly acidic.The six soil nutrients in the vegetable soil of Feidong were moderate spatial variability,and the ES>AP>AK>OM>AN>pH,the spatial variability of available phosphorus and available sulfur was higher.(2)Choosing an interpolation model suitable for different soil attribute characteristics is of great significance to reveal its spatial distribution law.The optimal semi-variance function model of effective phosphorus in Feidong vegetable land is Gaussian model,and the other five soil nutrient optimal models are index model.The nugget coefficient is ranked from large to small:pH>AK>AN>OM>ES>AP,soil spatial autocorrelation is not much different,and effective phosphorus has strong spatial autocorrelation.The nugget coefficient is below 0.25,and the organic matter,available potassium,alkali nitrogen,available sulfur and pH nugget coefficient are all between 0.25 and 0.75,and the spatial autocorrelation is moderate.(3)The overall nutrient status of vegetable land in Feidong County is moderate,soil organic matter is high in the south and north,and the trend is lower in the east and central and western regions,mainly 20-30g/kg,and the content of vegetable soil in the soil available phosphorus is higher.It is slightly lower in the east and north,and the soil available potassium is higher in the middle and north,and lower in the eastern part,with a concentration of 150-200 mg/kg.The soil alkali nitrogen is higher in the central region and the western region is relatively lower.The alkali nitrogen content of vegetables in the county is concentrated 150-200mg/kg.The soil available sulfur content is relatively low in the south,relatively high in the middle and north,and the soil pH is moderate.The soil pH is moderate in the northern and southern parts of the country,and the soil in the central and eastern parts is too acid.(4)According to the particularity of vegetable land,Delphi method,analytic hierarchy process and other methods,ait determines the establishment of 19 indicators for the evaluation of vegetable lands in Feidong County by adding groundwater depth,soil salinization and soil nutrient index which has great influence on vegetable production,among which the weights of organic matter,topographical parts,plough layer texture,soil salinization and pH are high,forming a set of index system suitable for quality evaluation of vegetable land.(5)The first-class vegetable land to the third-class vegetable land in Feidong County accounted for 25.26%of the vegetable fields in the county,mainly concentrated in the central and southern Binhu Plain,distributed in some towns and towns in the north and east,The fourth-grade vegetable land to the seventh-class vegetable land is accounted for 55.16%of the county's vegetable land,which is evenly distributed,and the central region is densely distributed.The eighth-class vegetable land to the ten-class vegetable land accounts for 19.58%of the county's vegetable land,mainly distributed in the northern and eastern regions.The average quality level of vegetable land in the county is 5.27,and the quality of vegetable land is mainly concentrated in 2-7class,accounting for 80.42%of the total vegetable area of the county,of which the vegetable area with the largest proportion is five-class vegetable,accounting for 16.36%,followed by 4-class and 6-class,accounting for 14.09%and 13.94%,the lowest proportion of 1-class and 10-class,accounting for 3.06%and 2.79%.The distribution of vegetable areas in the county has a normal distribution trend.