Spatial variability of soil properties in relation to land use and topography in a typical small watershed of the black soil region,northeastern China |
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| Authors: | Jian-Bing Wei Du-Ning Xiao Hui Zeng Yi-Kun Fu |
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| Institution: | (1) The Key Laboratory for Environmental and Urban Sciences, Shenzhen Graudate School, Peking University, Shenzhen, Guangdong, 518055, China;(2) Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang, Liaoning, 110016, China;(3) Gansu Agricultural University, Gansu, Lanzhou, 730070, China |
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| Abstract: | Soil degradation resulted from unreasonable land use and erosion has been a serious problem in the black soil region of northeastern
China. This paper seeks to understand the relationships between topsoil properties and topography and land use for land management
targeting at improving soil quality in this region. A total of 292 soil samples and 81 volumetric rings were taken from a
typical small watershed of the region in June 2005 for examining total carbon (TC), total nitrogen (TN), soil texture (classified
into gravel, sand, silt, and clay), and bulk density (ρ
b), respectively. Spatial variability of these soil properties was evaluated with classical statistics and geostatistics methods.
The results of classical statistics indicated that TC, TN, sand, silt, clay content, and ρ
b were moderate variables while gravel had great variability. Soil properties were mainly correlated to slope position, elevation
and land types. Geostatistical analyses showed that the spatial autocorrelation for TC, TN, and silt was weak, strong for
clay and moderate for and ρ
b sand, respectively. The spatial variations of soil properties are affected comprehensively by topographic factors, land use,
erosion, and erosion control in this watershed. Past erosion, however, is the most important component to induce change of
soil properties. In this small watershed, current soil and water conservation measures play an important role in controlling
soil loss. But the restoration of soil properties was unsatisfactory. Comparing with untilled soil of this region, TC, TN,
silt content are excessively low; whereas ρ
b, sand and clay content are excessively high; gravel appears at most sampling locations. It is necessary for improving soil
properties to protect forest and grassland and change cultivation system of farmlands. |
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| Keywords: | Soil properties Spatial variability Geostatistics GIS Northeastern China |
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