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Inner Mongolia Agricultural University (2010)

Spatial Variability Characteristics of Som and Total Nitrogen in Stipa Breviflora Desert Steppe under Different Grazing Intensity

Yu Na

Titre : Spatial Variability Characteristics of Som and Total Nitrogen in Stipa Breviflora Desert Steppe under Different Grazing Intensity

Auteur : Yu Na

Grade : Master’s Theses 2010

Université : Inner Mongolia Agricultural University

Résumé
Soil is not a homogeneous body while it has a high degree of spatial heterogenicity, which not only embodied in time but also in space. Traditional methods of description of soil spatial variability are essentially qualitative study of soil classification rather than quantitative study of soil spatial variability. This paper takes the light chestnut soil of Siziwang banner (Inner Mongolia) stipa breviflora desert steppe for example, using the basic principles of agrology, studying the organic compounds in meteorite and the total nitrogen on the grassland by applying the combination of classical statistics and goestatistics, it reveals the influencing regularities caused by the grazing intensity on characteristics of spatial variability in the organic compounds in meteorite and total nitrogen , the results show the following :(1) In the study area from 2007 to 2009, the annual average of the content of each grazing intensity of the organic compounds in meteorite and total nitrogen takes on an increasing trend, changes in the same year under the different treatments are : with the increase of the grazing intensity, the organic compounds in meteorite and total nitrogen took on a descending trend while dropping a little, only the content of organic compounds in meteorite in the heavy grazing pasture was significantly reduced compared with the no grazing area. The soil C / N changed little under different grazing intensities, the distribution types of the organic compounds in meteorite and total nitrogen were close to normal distribution, corresponded to the prerequisite based on the geostatistical study of soil spatial variability.(2)From the analysis of variogram, the organic compounds in meteorite and total nitrogen in certain field of study exists the spatial correlation between observations—the structural properties of spatial variability. This shows that in the range of A0 sample spacing, the observation of the sampling points is space-related.(3) The analysis of variogram model showed that the model fitting of the organic compounds in meteorite and total nitrogen is mainly consistent with the spherical and exponential model ; the isotropic analysis showed that the distribution of organic compounds in meteorite and total nitrogen in different directions is regulated. Grazing intensity affects the spatial heterogeneity of the organic compounds in meteorite and total nitrogen as well as their self-relevance, but did not show a change in law.(4)The graphic interpolation of organic compounds in meteorite and total nitrogen and nitrogen drawn by ordinary Kriging in the study area reflects the spatial variability. The trend of spatial variability of organic compounds in meteorite and total nitrogen was almost the same, the block with higher content of organic compounds in meteorite is much the same as the total nitrogen, which indicates that there is a clear correlation between the organic compounds in meteorite and total nitrogen.

Mots clés : Spatial pattern Som Total nitrogen Grazing intensity Stipa breviflora desert steppe

Présentation (Dissertationtopic)

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