Study On The Evaluation Of Regional Soil's Major Functions

Soil is the source of material foundation and precious wealth for people existence,and play an important action for human civilization and social development.But,with economy develop,industrialization and urbanization cause earth's surface permanent obturation,and cause the soil function largely lose and even completely lose such as yield function,buffering and purifing function,view function etc.This is not only relate a nation's continuable develop of social economy,but also deep influence ecosystem environment and globe change.Therefore,study on classification and evaluation of soil function is necessary.This paper consult foreign existing classification result of soil function, offer a groping classification project of soil function that accord with domestic.With each soil function's meaning,we definite the each soil function,and take it as foundation,select some indicators that can reflect the each soil function to evaluate it.Due to the restriction of data and time,we take Zhengzhou surburbs as an example,only evaluate the soil yield function,buffering and filtration function,and it can provide some basis and reference for classfing and studing evaluation of soil function ,and establish reasonable utiliztion and manage policy of soil resources.Main research contents as follows:1.Soil function classification:To make off a groping classification of soil functions from various functions such as resources, environment, economy, society and cultural etc.its'result sunch as yield function,buffering and filtration function,carring function,habitat and gene pool function, source of raw material function,archival function for natural history. we definite the each soil function,and describe some indicators that can reflect the each soil function.2.Set up analysis frame of activity-property-function,take soil property as a bridge,let various natural and artificial activity to contact to each soil function,and provide theories foundation for the follow-up research of soil function.3.Methods of soil function evaluation: Adopt two kinds of methods such as single factor evaluation and comprehensive evaluation.First,establish a referenced grade standard for single factor evaluation,evaluate the single factor's grading with the grade standard, in virtue of Mapgis to put a space value analysis for sample data,and form grade distribute chart of the single factor; Secondly, adopt the method of AHP and weighted aggregative index number for comprehensive evalutation of soil function.When fix the evaluation index,we evaluate I grade to 50,II grade to 30, and III grade to 20,so that can get the each factor's initial evaluation index;Finally,adopt frequency chart method to plot the grade of comprehensive evaluation,and show the result by figure.4.Evaluation of soil yield function: Take five areas of Zhengzhou surburbs as a case,and combine soil fact in Zhengzhou,we select seven indicators such as soil texture,pH,organic content,total nitrogen, available phosphorus, available potassium,and CEC to establish evaluation system of yield function and evaluate it,we plot three grade,and show the result by figure.The result show that,the best grade is only distribute in Huiji area,the east of city centre and a little of Zhongyuan area,because these area plant vegetable for long time,and plough fertilizer is more;the worst grade is largely distribute in the southwest and northwest of city centre,and Erqi area is most,soil type in this area is Cinnamon soil,the terrain is hill,and this area is dry,organic decompose quickly,the soil texture is light,and also the weights of organic and texture is higher than the others. Compared with achivement of agricultural land natural classification,we find that their distribution rule are similar,and explain that agricultural land natural classification is main decided by soil propertity.Study soil yield function is good or bad are very important to exchanging plant structure,improving crop output and how to use the soil resource rationally.5. Evaluation of soil buffering and filtration function: Take five areas of Zhengzhou surburbs as a case, according to the definition of soil buffering and filtration function,we select six indicators such as soil organic content,pH,CEC,bulk density,admissible environmental capacity,section plane texture type to establish evaluation system of soil buffering and filtration function, and use groundwater table distribution to correct the evaluation result, we plot three grade,and show the result by figure.The result show that,the best grade is mainly distribute in the southeast and part of west of city centre; the worst grade is main distribute in south of Yellow rive,Jialu river,and south of city centre. Compared with soil environmet evaluation result,we find that their distribution rule are similar,at the same time,it explain that soil is not pollution easily if soil's buffering and filtration function ability is strong, whereas,too.