DIFFERENCES ANALYSIS ON PHYSICOCHEMICAL PROPERTITES,MICROBIAL AND ENZYME ACTIVITIES OF CADMIUM CONTAMINATED PADDY

A field experiment was conducted in 2 hm² Cd contaminated paddy in Pingxiang, Jiangxi province, to study the spatial heterogeneity and correlation characteristics of soil physical and chemical properties, microbes and enzyme activities. The results showed that the variation coefficient of Cd in brown rice was larger than available Cd and total Cd in soil, and the variability of late rice was higher than that of early rice, which was with moderately variability. The coefficients of variation of pH and bulk density in soil was small, and the coefficients of variation of organic matter, cation exchange capacity, available potassium, available phosphorus and alkali nitrogen were in range of 22.82%~35.60%, with moderate variability. In addition to the variability of catalase was smaller, the variation coefficient of enzyme activity, mechanical composition and microaggregate in soil was 10.54%~38.21%, which was with moderate variability. The variability of microbes in soil was strong (in range of 52.59%~84.64%), in the sequence of bacteria > actinomycetes > fungi. Correlation analysis showed that pH, sand, invertase, acid phosphatase and catalase in soil had strong negative correlation with organic matter, cation exchange capacity, clay, available phosphorus, available potassium, fungi and urease in soil. While, there was a strong positive correlation between organic matter, cation exchange capacity, cosmid, available phosphorus, available potassium, fungi and urease. Principal component analysis results indicated that pH, organic matter, bulk density, available potassium and alkali nitrogen were key factors in soil physical and chemical properties.