Study on Available Copper Content in Cultivated Soils and Its Affecting Factors in Zhuhai

The Zhuhai city in Pearl River Delta was chosen as a study area. The soil samples were recollected according to the sampling points of Second National Soil Survey. Based on application of geographical information system (GIS) and SPSS software, the content, distribution and its influence factors of available Cu in cultivated soils were analyzed. The results showed that: the average available copper content in soil depth of 0-40cm of cultivated land in Zhuhai is 3.13mg¡¤kg-1, variation range is 0.02-99.96mg¡¤kg-1. When the soil depth of cultivated land increased, available copper content ranges rapid decreased. The rank of content range, average, standard deviation, variance, skewness and peakness of different land use types in decreasing order is vegetable soil > paddy field > dry land. Regression analysis using line equation, power function and exponential function between available copper content and affecting factors shows that: a positive correlation exits between pH and the available copper content in some soil depth. There is a remarkable positive correlation exit between the available copper content and organic matte. The available copper content and clay content also has a remarkable positive correlation. In soil depth of 12-27cm, the correlation coefficient of line equitation between pH and the available copper content is the biggest. In soil depth of 27-40cm, the correlation coefficient of exponential function between clay content and the available copper content is the biggest. In other soil depth, the correlation coefficient of power function between the available copper content and its affecting factors are the biggest. There are significant differences among nature affecting factors of available copper content in different depth of cultivated land. When pH ¡Ü 7.0 and pH £¾ 7.0, affecting factors of available copper content in soil depth of 0-12cm in decreasing order is organic matter > pH > clay content and clay content > organic matter > pH, while affecting factors of available copper content in soil depth of 12-27cm¡¢27-40 cm in decreasing order is clay content > organic matter > pH and organic matter > clay content > pH.