| The paper studied the soil micromorphology characteristics on different land uses pattems, trying to reveal the relationship between soil micromorphology and land use, and the information about land use and its. change recorded in the soil micromorphology. It is also a part of the National Nature Science Foundation (40471119). This paper chooses 3 profiles of different land use patterns in Nanniwan site, northern Shaanxi Prowince as study objects, such as Profile NNW1, land restored to forest; Profile NNW2, natural woodland; Profile NNW3, longtime cultivational land. Using Leica-DMRX polari-microscope and Sisc IAS V8.0 digital image processing system, observation and quantitative analysis about soil micromorphology of different land use pattems were carried out in laboratory, including thick grain, voids, micro-configuration, soil aggregate, organic matters and soil formation. The physical and chemical characters of soil, such as pH values, magnetic susceptibility and grain size, were measured and the relationship between the soil micromorphology and the land use pattern was discussed. Conclusions drawn in the study were as follows:1. While the quantitative analyses of soil micromorphology were carried out, digital images of different magnifying multiple have great infection on numerical value analysis. The most suitable multiple to Sisc IAS V8.0 digital image processing system is 10×10 multiples image. Normalization method can settle the problem of data dispersion degree when analysing the data.2. The soil micromorphologies of different land use patterns are distinct, mainly vughs-channels compound configuration in restored to forest land soil, mostly channels configuration in natural forest soil and spongy configuration in cultivational soil. The component of thick grain minerals is similar between different land use patterns, mostly quartz and feldspar, and also hornblende, mica, piedmontite and pyroxene. There are los of quartzose oddment in cultivational land and the shape of thick grain changes from semi-rotundity in BC layer to subangular blocky in Ap layer. The grain diameter changes greatly, and the grinding degree is high. The shape of thick grain changes from subangular blocky in BC layer to semi-rotundity in Ah layer of forest land soil, big diameter to 27.8μm. The shape of thick grain changes from subangular blocky in BC layer to semi-rotundity in Ah layer of the restored to forest land soil, small diameter, and high grinding degree. The grains have high grinding and thinning degree because of human's longtime cultivation. The packing voids are the most common voids types, channels and vughs in the second place, cranny, vesicles and chamber uncommonly. The wall of voids is rougher in cultivational land and slippier. The mostly component of soil formation is secondary calcites and clay. There are more speculate secondary calcites, less iron stained clays and optical directional clays in the restored to forest land soil. There are more iron stained clays, iron stained aggregate and secondary calcites. Secondary calcites filling matters are big in size in cultivational land, and the BC layer developed better than the Ap layer. Clay formation is common in the cultivational land profile and uncommon in the forest land. Ferruginous clay films and iron stained clay aggregate are not so common in the soils.3. The pH value of soil: Profiles of this study have high pH values because of their heavy alkali, pH values in the upper layers are obviously lower than the deeper layers in different land-use patterns, and lower in the cultivation profiles while higher in profiles belong to the natural woodland and the reclaimed land which has already been restored to forest. This implys that the pH values in land-use systems with strong human activities are lower than those with weaker human activities. The low pH values of the top soil in cultivational land profile due to the soil acidification which was caused by using acidification fertilizer on farming land. The distinction of pH values among deep soils of different land use patterns is unconspicuous, and won't change along with the depth increasing. This indicates the pH values of deep soil depend on the pedogenic conditions, and the land use patterns have less impact on it.4. The soil magnetic susceptibility: The low magnetic susceptibility among all the profiles implies that the airslake pedogenesis in this region was weak. In this study, the magnetic susceptibility of profiles under longtime cultivation is higher than the profiles of the natural woodland and the land restored to forest. This maybe relates to the enhancing pedogenesis caused by the human interference of longtime cultivation. And this is also the reason of the magnetic susceptibility doesn't change obviously in vertical direct of the farming profile. The magnetic susceptibility increases along with the depth increasing in restored to forest land soils and farming soils, but decreases in the natural forest.5. The grain size analysis: The forest soil which was disturbed least by human has the thickest grain size, the content of sand is the highest, about 21～25%. The grain size of farming land is thin because of longtime's farming, especially the heavy cultivated top soil (0～20cm), which has the highest clay, shows that the soil pedogenesis and improvement process of human's cultivation will thinning the soil mechanical composition.
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