Research On Spatial Variability And Impact Factors Of Soil Organic Matters In Beichuan River Basin

This study at exploring the spatial variability and impact factors of soil organic matters in Beichuan River basin by using different methods including GIS(Geographic Information System)technique, geostatistics, Person correlation analysis,variance analysis etc. It is indicated by the descriptive statistical analysis that the variation of the soil organic matter in this drainage basin ranges 77.58 ±36.19 g/kg,and the coefficient of variation is 72.31%, which is moderate degree of variation.The model of variation function is an exponential model, and the coefficient of nugget is 57.24% which is moderate spatial autocorrelation. It is indicated that the spatial heterogeneity caused by random factor is greater than that caused by structural factor(climate, parent material, biology and terrain etc.). The random factor is the principal factor that effects on spatial variability of soil organic matter in Beichuan River basin. The conclusion is drawn with the ordinary Kriging interpolation method that there are no significant spatial distribution regularities of the organic matter content in Beichuan River basin.It is indicated by the soil organic matter and Person correlation analysis and variance analysis of every impact factor: It appears that the organic matter content in soil has a significant positive correlation with altitude factor and the correlation coefficient is 0.375(p=0.022<0.05); a negative but not significant correlation with different slope gradients, the simple correlation coefficient is-0.088(p=0.605>0.05);a positive but not significant correlation with slope aspect, the simple correlation coefficient is 0.178(p=0.293>0.05); a significantly negative correlation with annual temperature, the simple correlation coefficient is-0.395*(p=0.016<0.05); a positive but not significant correlation with annual precipitation. the simple correlation coefficient is 0.035( p=0.835>0.05); a significantly negative correlation with PH value, the simple correlation coefficient is-0.596(p=0.000<0.01); a significant correlation with clay content, the simple correlation coefficient is 0.350(p=0.034<0.05); a positive correlation with silt content, the correlation coefficient is0.181(p= 0.284>0.05); a negative but not significant correlation with sand grain content in soil, the correlation coefficient is-0.25(p= 0.135>0.05).It is founded from the soil organic matter and variance analysis of every impact factor: the organic matter content in soil is not significantly different at different altitudes, the values of F is 2.185(p=0.093>0.05); not significantly different with different slopes, the value of F is 0.616(p=0.654>0.05);not significantly different between shady slope and sunny slope, the value of F is 0.003(p=0.957>0.05);significantly different at different annual temperatures, the value of F is 2.88(p=0.038<0.05);not significantly different with annual precipitation; p H values of soils in different ranges are extremely different with organic contents in the soil in Beichuan River basin, the value of F is 6.207(p=0.002<0.01);significantly different with different land-use methods, the value of F is3.52(p=0.017<0.05).The above analysis shows that altitude, annual average temperature, p H value,clay content and land-use type are the major factors effecting organic matter content in soil in Beichuan River basin.