A Study On The Evaluation Of Grade Of Soil Fertility Of Cultivated Land Based On GIS In Korla County Of Xinjiang

Cultivated land is the most important resource of agricultural production and the prime of land, fertility of which has a direct influence on food security and sustainable development of agriculture. Therefore, it is fundamental work of improving quality of cultivated land and properly making use of it to evaluate farmland fertility grade and analysis the factor and their change conditions affecting on soil fertility.Taking Korla city as the study area, the cultivated land fertility and its spatial and temporal variation characteristics have been studied and explored by combining the traditional soil survey method with modern3S (GIS GPS RS) technology in the thesis. Adopting traditional method of soil survey and combination of geological information system(GIS), geological position system(GPS), and remote system(RS)techniques, cultivated land fertility and characteristics of spatial and temporal variation have been studied and investigated in the thesis. Using soil testing and fertilizer data and in the support of GIS, management system of Korla cultivated land resource information will be set up and evaluation of cultivated land fertility have been made on the basis of collection of relevant datum and attribute data.According to soil map and present landuse map of Korla city, it is ensured by the superposition division method that there will be9171evaluation units, and11terms including organic matter, rapidly-available potassium, effective phosphorus, effective zinc, etc., have been selected as of cultivated land fertility of Korla city. Fitting the membership function, combination weights of various evaluation indexes will be calculated using hierarchy analysis method. At last, by calculating composite index of farmland fertility with addition, farmland fertility of Korla city have been divided into five grades.At the same time, in the process of the cultivated land fertility evaluation research, the author also has made the preliminary evaluation of the main soil nutrient status.The main research results obtained as follows:1) First-grade cultivated land has an area of368.37hm2accounting for0.85%of the cultivated land area in the whole city; second-grade cultivated land12418.51hm2, accounting for28.50%; third-grade cultivated land26186.34hm2, accounting for60.10%; forth-grade cultivated land3487.76hm2, accounting for8.00%; fifth-grade cultivated land1112.02hm2, accounting for2.55%.2) The cultivated land in Korla city has an overall generally low soil fertility, lacking of organic matter and nitrogen, with effective phosphorus content in the medium level; Trace elements such as the effective zinc content is in a "lack" state in almost the whole city. Most of the effective copper and iron is within the scope of "rich". The general conditions of the cultivated land in the city are relatively poor, and fertilizers structure is not rational. There are obvious differences in the conditions of the soil, water, light and heat in different terrain parts. The natural ecological environment and advantages in production are also variant in different regions.In the course of the study, the author has preliminary explored a set of effective methods and technology process applying GIS farmland geographic evaluation, so as to offer scientific basis for the quality of cultivated land protection and construction, scientific fertilization, constructing productive farmland, improving the comprehensive productivity and cultivated land ecological environment in the future.