Comparison of Micromorphological Features of Two Agricultural Cultivated Soils in Guanzhong Areas, Shaanxi Province, China

By comparing micromorphological features of irrigated and non-irrigated soils in Guanzhong areas, China, this paper tries to illustrate the influences of farming management methods on the soil-forming process. The micromorphology was observed under a petrographic microscope and its image was quantificationally measured by Nikon NISBR 2.2 software. Both irrigated and non-irrigated soils have the same soil profile pattern, Ap1- Ap2- BC, but the former has a more obvious profile dissimilation. The minerals assemblage of soil profiles A and B are very similar, which is mainly composed of Q and Pl. Compared with non-irrigated soil, grains of irrigated soil remarkably decrease in length, area, eqdiameter, perimeter, elongation, roundness, and C/F10μm ratio; voids are characterized by more regular void shape and more smooth void wall; there is more abundant residual clay and small amount of illuvial clay. All results in this study suggest that the farming management method has influences on soil profile dissimilation and micromorphology. Agricultural irrigation could strengthen the degree of weathering, make smaller and rounder soil grains, cause a significant increase of residual clay and appearance of illuvial clay. But no significant change has been observed in the minerals assemblage of coarse grains.