Spatial-temporal variation of soil available P and K in Taihu Lake region of Jiangsu province，China

Better understanding of soil nutrient spatial．temporal variability is the basis for rational soil management and fertilization．In this paper，spatial and temporal variability of soil available nutrients was analyzed in the studv area surrounding Taihu lake in Jiangsu province，taking available phosphorus(AP)and available potassium(AK)as two indicators，with the data from the Second National Soil Survey in 1982 and field sampling in 2004．bv traditional statistic and geostatistical technologies．The results showed that the average content of soil AP and AK went up from 1 982 to 2004．and the former increased more significantly．The area with levelⅡAP and AK content increased by 12.5% and 13.0%． respectively，and the area of levelⅢAP and AK content increased by 8.9％and decreased bv 13.4％．respectivelv．The area of level IVAP content decreased by 21．3％，and the area of levelⅣand I AK content，and level I AP content changed less than 1％．The largest increasing region of soil AP content was in the east of Changshu and around Taihu lake area of Yixing，and the largest decreasing area was in the east of Wujin．The content of soil AK increased obviouslv in the south of Yixing and the northwest of Wuxi，and decreased in mid-north of Yixing，Taicang and Zhangjiagang．These results provide a theoretical foundation for integrating research and management of soil quality in the studv area．