Assessment On Cultivated Land Fertility Based On GIS

Soil not only is the material basis for the survival and development of human, but also is the most basic source of all material production. Cultivated land not only is the elite of soil, but also is the most important resource of agricultural production. Cultivated land resource plays an important role not only in the development of agricultural production but also in the improvement of material life level of human.China is a big agricultural country and faces a sharp contradiction between human and cultivated land due to more people but less cultivated land, its per capita cultivated land is only0.095hm2, lower than half of the average level in the world. With the rapid development of economy, particularly with the progresses of industrialization and urbanization, a large number of cultivated land has been occupied which has led to the gradual decrease of cultivated land area. Now the degradation of cultivated land in China is very severe, mainly including soil and water loss, salinization, desertification and soil pollution. Moreover, the relative poor or weak of irrigation conditions and infrastructure of cultivated land in China inevitably lead to the frequent occurrence of drought and flood and the larger proportion of the middle-and-low-yielding fields in cultivated land (about2/3of total cultivated land). Thus, it is imperative to make clearly the situation and strengthen the management and protection of cultivated land resource in China.This paper took Langxi County of Anhui Province as the study region and CLRMIS as the application platform, dealt with the attribute data with ACCESS and the spatial data with ArcGIS, integrated the databases with CLRMIS, obtained the evaluation unit by overlaying the soil map, land use map and administrative map, selected13soil attributes as the evaluation indexes including the contents of soil organic matter, rapid available phosphorus and available potassium, etc., established the Analytical Hierarchy Process and the Membership Function Model by using Delphi Method, Analytic Hierarchy Process and Fuzzy Math Method with the incorporation of Expert Experience Method, and then evaluated the cultivated land fertility of each unit qualitatively and quantitatively. The cultivated land area of Langxi County was58371hm2with2081defined evaluation unit of cultivated land. Cultivated land was classified into5grades according to the summation curve of the Cultivated Land Fertility Comprehensive Index (IFI). According to the obtained Cultivated Land Fertility Evaluation Result Diagram, the1st grade of cultivated land was of13321hm2,22.9%of the total cultivated land area, mainly were the paddy fields with high-stable yield and good irrigation and drainage conditions in the gentle region of towns of Nanfeng, MeiZhu etc; the2nd grade cultivated land was of19526hm2,33.4%of the total cultivated land area, mainly distributed in the central hill region of towns of Shizi, Taocheng etc; the3rd grade cultivated land is of17772hm2, mainly distributed in towns of Biqiao, Lingdan, Xinfa etc., these cultivated lands had a high ground water level, soso irrigation and drainage conditions and obvious barrier layers. The4th and5th cultivated land were of6663hm2and1089hm2,11.4%and1.9%of the total cultivated land, mainly distributed in the mountain and hill regions of towns of Lingdan, Shizi and Taocheng etc., these cultivated land had poor irrigation and drainage conditions, low nutrient contents. The5th grade of cultivated land usually located at the mountain slopes with high difficulty of tillage.Through this study, a preliminary evaluation system was established suitable for the cultivated land in Langxi County, the classified grades of cultivated land fertility and their spatial distribution were according with the actual situation of agricultural production, the resources of cultivated land in Langxi County was recognized clearly. These above results provide the scientific bases for the suitable utilization of cultivated land, the developments of regional advantages and the specialized agriculture. Besides, this evaluation system can be used to setup the information storages of cultivated land resources, which can provide the theoretical bases and scientific guarantee for the improvement of the quality of cultivated land, the structure adjustment of farm production, reasonable and scientific fertilization, the pollution decrease of soil environment, the sustainable utilization of cultivated land, etc.