| Soil organic matter is an important part of soil. It is an important indicator to evaluate soil carbon pools and soil fertility. Revealing the spatial distribution and variation of soil organic matter can provide the basis for the cropland management measures and the reasonable agricultural planning. Using remote sensing image to research the soil organic matter has advantages in timeliness, accessibility, accuracy and wide area, which can get the distribution of soil organic matter quickly. This paper is to research the distribution and variation characteristics of soil organic matter in Shanxi Province by use of TM remote sensing image, which has great significance in strengthening the quality of cultivated land in Shanxi Province. Moreover, it can provide a basis to the soil fertility regulation and the study of soil organic matter in future in Shanxi Province.This study use the remote sensing image to analyse distribution of soil organic matter content in Shanxi Province from1987to2008. The pretreatment was carried on the TM remote sensing image, which including radiometric correction, geometry correcting and so on. Extract arable land and collect evaluation data of Shanxi Province in2008. Shanxi Province is divided into four regions according to the topography. then analyse organic matter content of the samples, spectral values of the corresponding remote sensing image and various transformation indicators of four regions in Shanxi Province by using SAS software. Inversion model of soil organic matter content in their respective regions are established and validated. These models are applied to TM image to form the cultivated land soil organic matter content of Shanxi Province in2008. On this basis, this article make TM images in1987at the same level as images in2008. Take images of1987into soil organic matter inversion model to form the cultivated land soil organic matter content of Shanxi Province in1987. Finally, combined with soil type to research the variations characteristics of soil organic matter in recent20years.The main results and conclusions are as follows: (1) Soil organic matter content inversion model of four regions in Shanxi Province are as follows:1) Inversion model of soil organic matter content in the south central Ln(SOM)=39.4×R1×R4-240.3×lnR4-106.6×lnR5-1.6/R4-534.9×log(1/R4)-241.9×log(1/R5)-5.6(R2=0.62)2) Inversion model of soil organic matter content in the eastLn(SOM)=244.9×R1-1911.3×R1×3+863.4×R32-3.2×log(1/R6)’-11(R2=0.59)3) Inversion model of soil organic matter content in the north Ln(SOM)=-52.3×R1×R7-116.9×ln R5-0.8/R2-3.7/R4+10.3/R5(R2=0.58)-334.8×log(1/R3)-373.5×log(1/R4)+18.34) Inversion model of soil organic matter content in the west Ln(SOM)=194.5×R1×R4-612.5×R2×R4+653.7×R2×R7-71.5×R72(R2-0.55)-182.7×lnR7+1.1/R1,-1.6/R4-399.4×log(1/R7)-17(2) The spatial distribution of soil organic matter content of Shanxi Province in2008showed that the soil organic matter content on northwest is low, and soil organic matter content on southeast is high. The soil organic matter content is mainly between3.42-29.62g/kg. Use geostatistics to compare and analyse the results, it showed that the accuracy of organic matter content by use of TM images is more consistent with the actual situation.(3) Analyse and compare the changes of the cultivated land soil organic matter content, we find that the most of the cultivated land soil organic matter content in1987are between7.39and12.18g/kg, and the most of the cultivated land soil organic matter content in2008are between8.66and13.91g/kg. Soil organic matter in Shanxi Province is basically an increasing trend. In addition, according to the soil types in Shanxi Province, we calculate the variation of the average organic matter content for various soil types in the past20years. The results showed that organic matter content of brown soil, loessal soil, paddy soil and meadow soil are decreased, and other soil organic matter content are increased. |
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