Abstract:Combined with maize yield information, 13 indicators of soil micromorphology were selected as the evaluating indicators, soil thin section technique, Photoshop and Image-pro plus 6.0 software were used to qualitatively and quantitatively evaluate sandy soil fertility under different improvements based on a field test in Horzin of Tongliao city, Inner Mongolia, and then MDS of soil micromorphological indicators was setup to simplify the evaluation process. The results showed that characteristics of soil microstructure, soil aggregate, colour of soil matrix and skeleton grains were similar under different treatments. Clay particles in unit 10 (values of clay, organic fertilizer and humic acid were 3.00×105, 3.00×104, 7.50×103 kg/hm2, respectively) were higher than other units, and also its ratios of soil matrix and frequency of organic matter were the highest. The degree of porosity development in unit 8 (values of clay, organic fertilizer and humic acid were 1.50×105, 3.00×104, 1.125×104 kg/hm2, respectively) was higher than other units, but the capillary pores were better developed in unit 13 (values of clay, organic fertilizer and humic acid are 7.50×104, 3.00×104, 3.75×103 kg/hm2, respectively). The weights of soil matrix, soil pore, organic matter, soil structure and skeleton grains in the rule layer were 0.33, 0.253, 0.203, 0.124 and 0.084, respectively; There were 7 indicators in the established MDS of soil micromorphology, i.e. ratio of soil matrix, type of soil matrix, colour of soil matrix, percentage of capillary pore, type of pore, type of organic matter and average diameter of skeleton grains. The MDS evaluated result was highly correlated with the original evaluated result, which indicated that the established MDS can feasibly replace original 13 indicators in evaluating sandy soil fertility.