Research On The GIS-based Fertility Evaluation System Of The Farmland In Nong'an County

Fertility of farmland is the potential productivity of the natural factor of the farmland in the production of agriculture products,for farmland is the basic capital foods in the agricultural production.Fertility of farmland is a new concept raised by the agriculturists according to the quality of farmland.The crops can grow and have large output on the condition of good fertility; whereas the crops grow poorly and have low output.The direct standard to judge the fertility of farmland is that of the soil.We use the organic content,soil nutrient,physical property of soil to judge the fertility of soil,and yield index as well in the practical production.In fact,based on the nature of farmland and directed towards the fertility construction and improvement of soil,fertility means to make sure the sum of all the factors of fertility of fixed type of soil in the fixed area.It is a concept of reflecting the inner and basic nature of farmland,since carrying out the reform and opening-up policy,the quality of farmland and the fertility of soil in China has changed a lot with the change of rural economic management system,forming policy,types of crops,planting structure,output level,application amount of organic manures and fertilizer, variety structure,and application of the pesticide,etc.With Chinese agriculture entering into a new stage since the 21^st century,carrying out the fertility evaluation has become an important and urgent foundation task.In the stage of continuous improvement,the theoretical system and methods of Chinese land resources evaluation still need further research. Therefore,it has great significance to finding out the fertility condition,fertility level,nutrient status,soil degradation condition,and the comprehensive capacity of the farmland in China,raising the comprehensive capacity of farmland,realizing the high productivity of agriculture,increasing the income of farmers,improving the sustainable development of agriculture by the new GIS-based farmland fertility evaluation methods.GIS is a new technology developed internationally since 1960s.It is a kind of computer system making use of the modern computer graphics and database technology to deal with the geographical space and related data.GIS is a comprehensive new and high technology involving geography,surveying, geometry,computer science and applied object.The greatest feature of GIS is that it can organically combine the geographical position of the matter at the earth's surface with its characters and display the result visually and intuitively through the screen of computer.This feature makes it more versatile. Choosing Nong'an County in Jilin Province as the object of study,this assay puts forward a method of fertility evaluation of the farmland in a county based on the Fuzzy Mathematics Model by using GIS,RS,GPS,AHP,and method of expert's evaluation.The main content of this assay is the research on the fertility evaluation system of the farmland.According to the actual need,we developed a small drawing program during the research by using Visual Basic in the process of research including opening the based drawing in the form of JPG,digitization of point,line and face,and the property setting.In the process of digitization, we can do some operations such as zooming up or zooming down the pictures. It is simple and convenient to operate the interface in Chinese.Then the digitized diagram will be laid in evaluation system.In Chapter One,it introduces the background of the paper,purpose and the significance of the research,and the basic condition of the object area.In Chapter Two,it introduces how to collect and sort out the related data, diagrams,and information;according to the stationing principles and methods fix the location of the sampling points with the distribution condition of the practical soil types,current application of the land,and the types of farmland; sample with GPS outdoors and record simultaneously the profile characteristics and site condition,etc;analyze the nutrient content of the sampling soil indoors.In Chapter Three,it introduces how to scan and digitalize the soil diagram,the current land utilization diagram,and administration division map of Nong'an County;how to vectorize all the diagrams including the setting of diagram of sampling point's position,judge the correctness of the position of the sampling points;do the interpolation by the analysis data of the sampling points and make the nutrient content diagram in the whole county(including organic substance,total nitrogen,available phosphorus,potassium,copper,zinc,iron,and manganese);it introduces three common methods and principles of interpolation,and we use Kriging here;how to make the slope gradient and aspect map by contour diagram; how to form the evaluating unit by the digitalized diagrams and add up the research data and the interpolation data.In Chapter Four,it introduces the AHP including how to fix the evaluating factors.As for Nong'an County,we select 19 factors in five respects,i.e.cross section and physicochemical character,site condition,meteorological factors,soil nutrient,and soil management,etc,as the basis for evaluation;how to calculate the membership function of the digital evaluating factors by SPSS;how to judge the importance of the evaluating factors by the method of expert's evaluation; how to construct the multistage model of farmland fertility evaluation;how to do the level analysis of the farmland fertility evaluation in Nong'an County;at last, calculate the comprehensive index of farmland fertility and divide the fertility level.In Chapter Five,it introduces the calculating method of comprehensive index of the farmland fertility;ascertains the classification plans for comprehensive index,and classifies the levels;falls into the national farmland fertility level system according to the national index;how to do the makeup of the results.In Chapter Six,it makes a conclusion of the project;displays some of the achievements;briefly introduces the application of the achievements in some respects.Using the 3S technology,the method of fertility evaluation of the farmland raised by the research has a great realistic significance to the analysis of the temporal and spatial variation of farmland-fertility and factor of soil fertility, obtaining the amount,quality,and distribution of the farmland resources, rational utilization of the farmland in Nong'an County,protection and improvement of the fertility of the farmland,set-up of the agricultural projects, and development of modern science and technology in agriculture.