Study On The Characteristic Of Purple Soil Electric Conductivity In The Hilly Region Of Sichuan Basin

By using correlation coefficient and Fuzzy, the paper basically discussed the characters of main purple soil electric conductivity (the black purple soil, the grey-brown purple soil, the brown purple soil, the red-brown purple soil) in the hilly region in Sichuan, discovered the variation feature of the purple soil electric conductivity under different conditions, established the correlation coefficient of purple soil electric conductivity( EC) and soil fertility.The analysis of the characters of EC showed that the purple soil EC was low in the whole area, the maximum was only 334.00μScm~-1,the minimum was 70.00μScm~-1,the was far blow the critical point of salinized and non-salinized soil.By studying the changing of EC under different conditions, the result showed that the purple soil EC was obvious difference. The variant trend of EC in the different stratum was: the EC of the brown purple soil was highest, the EC of the red-brown purple soil was lowest, the EC of the black purple soil was higher than that of the grey-brown purple soil. The changing trend of EC in the different hill was: the EC of the high hilly region was highest, the EC of the low hilly region was lowest. The changing trend of EC in the different slope place was: the EC of the foot of hill was highest; the EC of top of hill was lowest.The salt ion of purple soil was composed mainly of Ca+ and HCO3-,it was significant positive correlation between four main purple soil EC(the black purple soil, the grey-brown purple soil, the brown purple soil, the red-brown purple soil)and the total salt.The regression equation of black purple soil was y = 700.33x + 76.77 (n=12 , r=0.797**),the regression equation of grey-brown purple soil was y = 816.75x+ 87.84 (n=18 , r=0.842 *),the regression equation of the brown purple soil was y = 750.28x + 82.46 (n=60, r=0.774**), the regression equation of the red-brown purplesoil was y = 911.51x +18.59 (n=12, r=0.757**)o (y represented EC and x represent totalsalt).The result of correlation showed the purple soil EC was related mainly topH ,CEC ,organic material and bulk density ,which effect the purple soil EC.The results of soil quality evaluation showed that: the integrated Fertility index of the purple soil and purple soil EC was significant positive correlation in hilly regionSichuan, and the regression equation was y = 0.43x2 +2.62x + 0.11 (n=60, r=0.978)(The y was the integrated Fertility index and the x was electric conductivity.),so estimating unsaline purple soil fertility , the soil EC could be used to act a reference quantity index as evaluating soil fertility.