| The distribution of karst landform is to centralized the west part of South China, where there is large of mountain area, the karst soil formation rate is slow, soil is thin, the tolerance of soil loss amount is low, the risk of degree of soil erosion is high, stony desertification is serious, the loss of soil nutrient and vegetation restoration difficulties become vicious spiral. To have a thorough understanding of soil nutrient distribution in this area, which is useful to establish right evaluation system of soil nutrient of Karst plateau.In this study, combined with field investigation and indoor analysis, soil samples were collected from the typical site of Karst hilly plain in Wangjiazhai, Qingzhen county, Guizhou province, China.,with the soil developed under the carbonate rock.combined with GIS and GPS,using80×80m grid layout point of0-150cm topsoil to take soil samples248, which include97of dry land,19of paddy and132of shrub land. The content of SOC, TN, TP, TK, AN, AP, AK and pH value were analysed. The research discussed the spatial distribution character and the disciplinarian variance. Simultaneously, the soil nutrient indexes were used as the evaluation factors, with the application of Fuzzy comprehensive evaluation method, to make a comprehensive evaluation of soil fertility quality, the main research results are as follows:(1) Moran's I coefficient method was used to eliminate the abnormal value from testing data, and the normal test of the indexs were made at the same time. The soil nutrients are the medium-degree variabilities., the coefpilient of variationof AP was90.93%, which is close to strong variability, and the coefpilient of variation of pH was10.09%, close to the weak variation. The coefficient of kurtosis of TK was high up to5.0057, while the coefficient of kurtosis of AN is2.4088, the the coefficient of kurtosis of the other indexs are keep float among2.5～3.5, which are closed to the coefficient of3, all the coefficient of skewwnee low.(2)The semivariogram of SOC, TN, TP and pH were best described by Exponential, The coefficient of determination are0.977,0.972,0.962and0.843; The semivariogram of AN and AK were also best described by Exponential, the coefficient of determination are0.687and0.717;and the TK and AP were best described by Spherical, the coefficient of determination are0.684and0.917; The ratios of nugget to sill indicated that the spatial autocorrelation of SOC, TN, TK and AP inches were moderately dependent, and the nugget to sill of TP, AN, AK and pH are similar, which are floating among9%～13%. and showed a strong spatial autocorrelation.(3)Land use is significantly affect the content of soil nutirnets, under different land use, the content of SOC in shrub land was the highest, and the content of TN were exhibited a consistent trend. In paddy, the content of TP is significantly lower than that of dry land and shrub land, and the average is0.68g/kg, for TK, the content of dry land is significantly higher than that of shrub land, between dry land and paddy field, paddy and shrub land, there are no significantly difference. In paddy,the content of AN and AP were significantly higher than that of dry land and shrub land; The content of AK is significantly lower than that of dry land and shrub land; Under different land use the pH value in shrub land pH the highest, but thelowest in paddy(4) The soil fertility quality are the same under different land use, all the soil fertility o belonging to grade Illand the composite index of soil fertility are0.68,0.69and0.72. |
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