Study on spatial heterogeneity of farmland spectrum based on TM data

The spatial structure of farmland spectrum extracted from 2 scenes of TM image was analyzed by means of the geostatistics．The results show that there is the obvious semi-variance structure for the pixel grey level of three bands in most section；and the semivariogram plots can be fitted by Spherical and Exponential models res pectively， while Power model can be used in saline soil region；the proportion of structural variance to sill is in a higher leve1．from 41％ to 96％ ．The limited distance of spatial correlation is 6～45 pixels．