Micromorphological Features Of The Cultivated Soils In The Middle Reaches Of The Jinghe River

At present the research about the micromorphological characters of tillage soil is mainly focus on the characters of the modern soil, and scholars work hard on the changes of the voids and microaggregates under the different tillage practices or years in order to provide science gist about the judgments of soil fertility. But the research about the characters of old-cultivated soil is little. Along with the increasing importance of the natural factors, scholars begin to focus on how to exactly judge the influence about the natural and artificial factors that both anfractuous complected together to change the characters of the soil micromorphology. And this research is the key to unscramble the information of the land use, land degradation and environmental changes that included in the soil micromorphology.Through the observing and describing under the microscope, this research also apply the software named Leica Qwin that one of the most advanced software to analysis the micromorphological features of the modern soil, the old-cultivated soil and the paleosol. And the coarse grains, voids, microstructure and the pedofeatures were observed, described, measured quantitatively and done the number simulation, so the information that included in the features of soil micromorphology was released intensively. Then this paper summed up the micromorphological features of the modern soil, the old-cultivated soil and the paleosol.The coarse gains of the three soils are all mostly consisting of quartzes, feldspars etc. that can't easily weathering, and the surface roundness are different. There are a few medium alterations biotitic and few hornblendes. The phenomenon of exists of cracked quartzes is usually in the modern soil. And there are some large compounded quartz grains and platy single crystal of quartz or feldspar in the old-cultivated soil.With regard to the microstructure, the modern soil is belonging to the vugh-channel complex microstructure, and there are a lot of bio-voids and well-development crannies. The other two soils are belonging to the spongy microstructure. The shapes of the voids chiefly are cylinder, arch or equidimension, and hollow butt and wormholes are smooth and very developed with few crannies in the paleosol. The voids are the mostdevelopment in the paleosol;the groundmass has been already developed to the porous crumbs.The pedofeatures are mainly excrements of earthworms, pedogenic calcites and clay pedofeatures in these soils. In the modern soil, the pedogenic calcites have poor and short development, this is the same with the clay pedofeatures which are impregnated by Fe weekly, and the pedogenic calcites and clay pedofeatures often mixed together and form the faintness limits compared to the groundmass. There is an especial feature in the modern soil, which is the crescent intercalations of pedogenic calcites, and also has not only one layer. The development of the pedogenic calcites is stronger, and a few large infillings of the pedogenic calcites exist in the old-cultivated soil, the clay pedofeatures consist of circular clay-aggregates impregnated by Fe with different degree and the optical directional clay which development weakly. Acicular pedogenic calcites in the paleosol are developed mostly in the three soils, and distributed along the rough surface of the crannies. There are two kinds of clay pedofeatures in the paleosol;one is the clay pedofeatures which is impregnated by Fe but without the directional opticity;and the other is the ones with directional opticity to form the crescent clay coatings. For the earthworm, it is the most in the modern soil which fill in the voids and mostly remain the origin elongate shapes. The excrements of earthworms are distributed as direction in the old-cultivated soil, but that isn't the same in the paleosol.This is the same about the types of the organic constituents in the three soils. The residues of plants exist in all, but with the different forms. In the modern soil, the organic constituents are many residues of plants which are brightness, red or wine and fresh. But the organic matters are few dark tissue residues of plants that are decomposed strongly in the other two soils.