[Study on the main influencing factors of black soil spectral characteristics]

To develop soil properties quick measuring methods, promote the development of quantitatively remote sensing studies relating to terrestrial ecosystem, and deepen the application of remote sensing in agriculture, the hyperspectral reflectance of black soil in Songnen Plain, northeast China, was analyzed with spectral analysis methods (continuum removal, spectral angle match and spectral feature fitting) and statistic methods to discover the reflectance spectral characteristics and its influencing factors. The results are as follows: the soil parent material determines the basic characteristics of reflectance of the black soil, which is the mixture of montmorillonite and illite, and consistent with mineral analysis result. Organic matter is the main factor determining the curve shape of black soil reflectance in the region shorter than 1 000 nm, and indirectly influencing the reflectance in the region longer than 1 000 nm because of the correlation with soil moisture and mechanical composition. The varying process of soil reflectance with changing soil moisture can be quantitatively described with cubic equation, and moisture mainly changes the reflectance value but not the curve shape. Black soil reflectance is not influenced significantly by Fe, which is different from soils of south China. Roughness mainly impacts on the soil reflectance value but not the shape feature. The spectral feature of straw reflectance is remarkably different to that of black soil, and impacts on both the value and curve shape of black soil reflectance. Different soil tillage measurements result in different moisture holding ability and the amount of straw for different farm fields, and influence the reflectance further, with the order of soil reflectance from high to low is: no tillage, moldboard tillage, combination tillage, reduced tillage, and rotary tillage.