Cultivated Land Quality Assessment Based On SPOT Multispectral Remote Sensing Image And GIS

Land is the important resource basis for human and social survival and development and also is the most important unsubstitutable production substance for agricultural production .The situation of land quality affect agricultural production efficiency greatly and has familiar relationship with agriculture and social sustainable development.Especially in the population-resource-environment sustainable land use system, land resource stay at the basic status. Following with the further promotion of the socialism modernism, the land resource status, especially the cultivated land fertility and arable land environmental quality is changing step by step. Human-induced cultivated land change and the effects to eco-environment and human life had attracted people's abroad attention. So in order to satisfy the demand for sustainable development and resource–environment sustainable use, it is necessary to carry out the land quality assessment, analysis the cultivated land quality change.At present, the studies on cultivated land quality assessment are mainly based on GIS technology and combination of GIS and RS, with RS mainly used to obtain and update the basic data. Few studies based on RS technology directly to implement land quality assessment. In the study, the outline of the studies on cultivated land quality assessment in home and abroad and the applications of RS and GIS technology to cultivated land evaluation were firstly introduced, then by virtue of all the data from the program National Cultivated Land Fertility Survey and Land Quality Evaluation, take Jimo City as a case study, which was the experimental unit in Shandong Province for cultivated land quality program, with support of the RS technology, the cultivated land information data was obtained and cultivated land quality indicator were extracted, the indicator system and evaluation model were build up. Thirdly, the result was compared with the evaluation based on GIS technology and the advantage and disadvantage in evaluation method, evaluation model and their application were discussed. At last, the characters in different ranks of cultivated land were discussed and measures for sustainable land use were recommended.SPOT Multispectrum was the data source in this study. According to the consistency of land spatial configuration, the characters of vegetation cover and image itself, the cultivated land information was interpreted by supervised classification. The result showed that the cultivated land area in 2004 is 101967.3 ha,with crop land 95800.18 ha,establishment vegetable land 1171.2 ha,the hypaethral vegetable land 4995.91 ha.Based on RS technology, cultivated land quality assessment factors were extracted from SPOT multispectrum image, with different vegetation index NDVI ,DVI, RVI, slope and land use to reflect soil fertility status, water information and land degradation information. Supported with ERDAS moder maker module, the evaluation model was set up and cultivated land quality evaluation was carried up. The research separated the cultivated land into rank 6.The proportion of ClassⅠis 17.2%,it has the best quality and mainly distribute in middle and west with the establishment vegetable land and perfect crop land as the main land types. ClassⅡwhich proportion is 24.9%,mainly distribute in northwest wash east hill area , plain at the foot of the hill and terrace land along the river. ClassⅢmainly distribute in terrace and the rank land near the mountain and the proportion is 26.5%. ClassⅣ,14.3%, mainly distribute in terrace and the rank land near the mountain, with the general quality. Most ClassⅤwhich proportion is 15.6%,distribute in the terrace in east ill area, with the worse quality. ClassⅥ,1.5%,mainly distribute in the wild slope land in east hill area, with the worst land quality.Comparing with two kinds of assessment methods based on RS and GIS, the result showed that evaluation based on RS had a perfect precision, the percent of all ranks and the spatial distribution keeps consistent. It showed that in cultivated land quality assessment, the RS technology not only could supply basic information, but also be as a direct method to get indicator information and build up assessment model. Then many of advantage of RS technology would be realized. However, GIS software keep superiority in spatial analysis, so if the advantage coming from GIS and RS combined, the better result would be available in cultivated land quality assessment.The study carried out the cultivated land quality in Jimo City and some policy and suggestions on regional arable land sustainable use are brought forward. Especially, the cultivated land quality assessment basing on RS technology supplied a new route for quantity assessment.