Soil Health Assessment Of Typical Agricultural Land In Zigui County

Soil health of agricultural land is the important guarantee for maintaining food security in China.To explore the soil health level of different agricultural lands,we take citrus orchards,dry lands,and paddy fields in Zigui County as the research objects.This study combines the physical,chemical,biological,and environmental properties of soil to develop an evaluation system for soil health of different types of agricultural land.On this basis,the spatial distribution of soil health in agricultural land assessed and its limiting factors are discussed.Meanwhile,a soil health evaluation software based on VS.NET is developed to realize automation.The main research conclusions are as follows:(1)According to the existing evaluation systems of soil health,this study develops a similar approach for citrus orchards,dry lands and paddy fields in Zigui County.The citrus orchards and dry lands include various evaluation indicators,namely,physical(bulk density,texture),chemical(p H,organic matter,total nitrogen,available phosphorus,available potassium,available zinc,available boron),biological(biodiversity),and environmental(arsenic,cadmium,chromium,lead,mercury).By comparison,the evaluation indicators of paddy fields differ by replacing available boron with available silicon among the chemical indicators.The weight of evaluation indicators is the weighted average score obtained from95 survey questionnaires answered by government departments,researchers,technicians,and frontline farmers.The membership degrees of numerical indicators are determined by using the membership function,and that of conceptual indicators are determined by using the standard values of the National Cultivated Land Quality Grade Evaluation Indicator System.The soil health index is obtained by multiplying and then accumulating the weights and membership degrees of each indicator.(2)The results of spatial analysis show that the overall agricultural soils in Zigui County have high bulk density,small p H,high content of organic matter,available phosphorus,available potassium,available zinc,available boron and available silicon,medium content of total nitrogen and high richness of biodiversity;the soil texture is mainly medium loam and sandy loam.In addition,the content of soil arsenic,cadmium,chromium,lead and mercury are low,and none of them exceed the screening values.In addition,soil bulk density and organic matter,p H and available phosphorus show significantly negative correlations,while a positive correlation is observed between organic matter,total nitrogen,available phosphorus,and available potassium.(3)The soil health indexes of agricultural land in Zigui County are calculated and results show an overall high level,with the average values of soil health in the order of dry lands > citrus orchards > paddy fields.Most soils in the citrus orchards are healthy;soil health in Shazhenxi Town,Guojiaba Town,and Yanglinqiao Town are relatively good;and that in Maoping Town is relatively poor.Most soils in dry lands are extremely healthy,and those in the southern area have better health than those in the north.The health of most soils in paddy fields are healthy,and the healthiest and poorest soils are in Yanglinqiao Town and Maoping Town,respectively.The main factors affecting soil health in citrus orchards,dry lands,and paddy fields are physical and chemical indicators.Overall,the poorest soils have too high or too low bulk density,excess clay or sandy soils,extreme soil alkalinity or acidity,and low content of organic matter and nutrient elements(nitrogen,phosphorus,boron,zinc).In Zigui County,the soils with sub-health are concentrated in the central and southern parts of Xietan Town and the central and northern parts of Maoping Town.The soil health in the abovementioned regions can be improved by increasing the input of potassium and boron fertilizers,planting green manure,and strengthening the treatment of industrial wastewater waste near agricultural land.(4)Based on VS.NET platform and C# language,this study develops a soil health evaluation software by using object-oriented technology.The evaluation system includes four functional modules,namely,creating an evaluation indicators system,editing indicator parameters,creating/importing soil data,and calculating soil health indexes.The software provides a platform for the universal application of soil health evaluation systems.