Abstract:

The arrangement of soil particles is a basic factor affecting soil pores.The characteristics of soil voids can be directly observed and quantitatively analyzed through the method of soil micromorphology.Liaocheng City is in the west part of Shandong Province,China and is located at the Yellow River alluvial plain.The fluvo-aquic soil accounts for 94% of the total soil area in Liaocheng City.In order to determine the effect of soil texture on soil voids of fluvo-aquic soil,the samples of loam,clay loam,and sandy loam were collected in Liaocheng City.The comparative analysis of soil voids was conducted using the method of soil micromorphology and the normal method of soil physical analysis.The results showed as follows:(1) based on the normal method of soil physical analysis,the average total soil porosity in the depth of 0-25 cm was 54.29% in clay loam,50.16% in sandy loam and 50.40% in loam,and the average soil noncapillary porosity in the depth of 0-25 cm was 43.79% in clay loam,42.00% in sandy loam and 41.11% in loam.(2) the total soil porosity of three types of soil decreased from surface to subsurface soil layer.With respect to sandy loam,the difference of soil porosity between surface and subsurface soil layer is attributed to the soil capillary pores,which decreases from 55.89% to 6.40%.As with loam and clay loam,the difference of soil porosity between surface and subsurface soil layer was ascribed to soil noncapillary porosity.The soil noncapillary porosity decreased from 15.86% in the surface soil layer to 7.22% in the subsurface layer in clay loam and decreased from 16.38% in the surface soil layer to 5.02% in the subsurface layer in loam.(3) according to the thin sections of soil,the main shape of soil void in the depth of 0-25 cm is simple packing voids in the sandy loam.With respect to clay loam and loam,the main shape of soil void is compound packing voids in the depth of 0-10 cm,and the number of compound packing voids decreased in the depth of 10-25 cm,and (4) the total soil porosity analyzed by the thin sections of soil only account for 44.22% to 59.72% of those analyzed by normal method,whereas the soil non-capillary porosity measured by the thin sections of soil account for 73.50% to 95.02%of those measured by normal method.Thus,the thin section of soil is suitable for analyzing the characteristics of non-capillary porosities.

Key words: soil texture')">

soil texture, soil micromorphology, soil porosity, soil void shape