Study On Spatial Variability Of Soil Properties And Its Relationship With Environmental Factors In Jiangzihe Watershed Of Dabie Mountainous Area

The soil is the basic resources for the survival of human beings, and, it also is a naturalhistory of complex whose form and evolution are very complex. The study of the spatialvariability of soil properties can not only reveal the spatial distribution pattern of soil propertiesand their variability, but also better to explain the impact of natural and human activities onspatial variability of soil properties, so as to provide a scientific basis for guiding humanagricultural production, improving soil nutrient availability, precision fertilization as well asthe implementation of regional management.The Jiangzihe watershed in Huoshan county of Anhui province is taken as the study area inthis paper.111surface soil samples are collected and9indexes of soil properties are analyzedin laboratory such as pH, soil particles, organic matter（OM）, total nutrients（TN）, totalphosphorus（TP）, available nutrients（AN） and available phosphorus（AP）. Then the spatialvariability properties of surface soil are analyzed and the spatial distribution pattern of soilproperties are revealed by using the geostatistics, GIS spatial analysis. At last the paperdescribes the various relationships of soil properties and their environmental factors throughusing environmental factors related method. The results show that:（1） The average of OM, TN and TP in the study area are35.14g/kg,1.65g/kg,0.51g/kg,and the average of AN and AP are84.18mg/kg and100.64mg/kg.（2） The variation coefficients of soil properties varies from16.46%to67.71%, of whichthe highest coefficient of variation of available phosphorus is67.71%, relatively strongvariability, and the lowest coefficient of variation of sand content is only16.46%, indicatingrelatively low variability of sand content. The indicators of soil properties of the coefficient ofvariation are in the following order: soil sand, soil powder, soil clay, organic matter, totalnutrients, total phosphorus,available nutrients and available phosphorus, and the variance is inthe rang of10%to100%, all belongs to moderate variability.（3） The spatial variability characteristic of some properties of soil in the basin shows agood spatial structure, random variation is the proportion of3.84%to29.39%in total variance,of which the soil silt and sand of the C₀/（C₀+C） are greater than25%, a medium degree ofspatial autocorrelation, and the remaining indicators of proportion of the C₀/（C₀+C） is less thane25%, belongs to the strong spatial autocorrelation. Clay, TN, TP, and OM have alarge-scale spatial autocorrelation and their autocorrelation distances are all over250m, but silt,sand and AN and AP have a relatively small-scale spatial autocorrelation and theirautocorrelation distances are all below200m, of which the autocorrelation distances of silt andTP are the smallest, only183m, and the autocorrelation distances of clay is the biggest,2040m.The autocorrelation distances of soil properties are in the following order: AP, silt, sand, AN,TN, TP, OM, and clay.（4）The content of clay mainly concentrates between4.0%and8.0%, with an area of9049115m², accounting for77.65%of the total area, which of silt mainly concentrates between45.0%and51.5%, with an area of8685145m², accounting for74.53%of the total area, and thatof sand mainly concentrates between44.5%and47.5%, with an area of9767496m²,accounting for83.82%of the total area. The content of OM mainly concentrates between20.0g/kg and50.0g/kg, with an area of11067425m², accounting for94.98%of the total area,which of TN mainly concentrates between1.19g/kg and1.91g/kg, with an area of7800880m²,accounting for66.94%of the total area, and that of TP mainly concentrates between5.90g/kgand11.38g/kg, with an area of7874848m², accounting for67.57%of the total area. Thecontent of AN mainly concentrates between7.80mg/kg and87.78mg/kg, with an area of8616712m², accounting for73.94%of the total area, and that of AP mainly concentratesbetween77.91mg/kg and126.79mg/kg, with an area of7104975m², accounting for60.97%ofthe total area.（5） The following are the relations of the spatial distribution pattern of soil properties andenvironmental factors:①Clay, TN, TP and AP mainly concentrates between400m and800m in differentelevations, which the elevation zones of600m⁷00m account for the largest area, andgradually reduce in upward, downward of this band. Silt also mainly concentrates between400m and800m in different elevations, but the elevation zones of500m⁶00m account for thelargest area, and gradually reduce in upward, downward of this band. Sand, OM, and ANmainly concentrates between500m and800m in different elevations, which the elevationzones of600m⁷00m account for the largest area, and gradually reduce in upward, downwardof this band.②Clay mainly distributes in the10°³0°on the slope, accounting for83.9%of the totalarea. Silt mainly distributes in the slope that less than30°, which is centralized in10°²0°and20°³0°. Sand mainly distributes in the10°²0°on the slope, accounting for37.70%of the totalarea. OM mainly distributes in the10°³0°on the slope, accounting for37.60%of the total,following by20°³0°slope belt, the sum of the two accounts for71.10%of the total area. TN mainly distributes in the10°³0°on the slope, and TP, AN, AP mainly distributes in the10°³0°on the slope.③In different aspects, the South Slope which accounting for21.03%in total area is largest,with an area of2.44km², and it is followed by the Southeast Slope which is2.40km²,accounting for21.03%in total area. The smallest is Level Slope, which is0.01km², accountingfor1.00%of the total area. The content of soil properties is higher in the Southern Slope andsouth direction, and it is lower in the Northern Slope and north direction with the Level Slope.④The area of water conservation forests is largest, with an area of8.88km², accountingfor76.33%of the total area in different types of land use, and it is followed by rained paddywhich is1.34km², accounting for11.50%in total area. Vegetable plot is smallest, which is0.03km², accounting for0.22%of the total area.⑤In different vegetation types, the content of clay is in the following order: Bambooforest, deciduous broadleaved forest, coniferous forest, the evergreen broad-leaved forest,needle mixed forest and shrubs grass, and the content of silt is in the following order: Bambooforest, deciduous broadleaved forest, coniferous forest, the evergreen broad-leaved forest,shrubs grass and needle mixed forest. The content of sand is in an order of needle mixed forest,shrubs grass, the evergreen broad-leaved forest, coniferous forest, deciduous broadleavedforest, and Bamboo forest. The content of OM is in the following order: coniferous forest,Bamboo forest, deciduous broadleaved forest, the evergreen broad-leaved forest, needle mixedforest and shrubs grass The content of TN is in the following order: coniferous forest, Bambooforest, deciduous broadleaved forest, shrubs grass, the evergreen broad-leaved forest andneedle mixed forest, and the content of TP is in the following order: coniferous forest,deciduous broadleaved forest, the evergreen broad-leaved forest, shrubs grass, needle mixedforest and Bamboo forest. The content of AN is in the following order: coniferous forest,deciduous broadleaved forest, the evergreen broad-leaved forest, needle mixed forest, Bambooforest and shrubs grass, and the content of AP is in the following order: shrubs grass, Bambooforest, coniferous forest, needle mixed forest, deciduous broadleaved forest and the evergreenbroad-leaved forest.⑥By the multivariate linear regression model analysis, we can see that clay content andelevation, slope, OM content, land use types have significant positive correlation, which is asignificant negative correlation between it and the plane curvature. Silt content and elevation,slope, OM content, land use types show significant positive correlation, but it is a significantnegative correlation with the plane curvature. Sand content and elevation, slope, OM contentare significantly positively correlated relationship, with a significant negative correlationbetween it and aspect, vegetation index. OM content and slope, elevation, clay content, landuses are closely related, showing a significant positive correlation, with a significant negative correlation between it and the plane curvature. TN and elevation, vegetation index, clay content,OM content have significantly positively correlated, and it is a significant negative correlationbetween it and slope, plan curvature. TP content and elevation, vegetation index, clay content,OM content have significantly positively correlation, with a significant negative correlationbetween it and slope, surface curvature. AN content and elevation, clay content, OM contentand land use types have significant positive correlation, which is a significant negativecorrelation between it and slope, aspect. AP content and elevation, plan curvature, OM contentand land use types have significant positive correlation, with a significant negative correlationbetween it and slope, aspect.