ZHANG Run-yu, WANG Li-ying, CHEN Jing-an

(State Key Laboratory of Environment Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550002, China)

Abstract: Physical-chemical properties, contents and form distribution of phosphorus (P) in soils from the Lake Hongfeng Watershed were investigated during a drought period. The results showed that soil was acidic, with silt-dominating particle size composition. Water contents were slightly higher in soils from the water-level-fluctuating zone than those of abandoned land. Due to P deficiency in karst geological areas, total P and available P were below the national average level, ranging from 99.6 to 679.5 mg/kg and from 1.1 to 8.6mg/kg in top soils of the Lake Hongfeng Watershed. The highest values of total P and available P occurred in soils of management office and Houwu with heavy human activities, and gradually reduced with increasing soil depth. Soil P forms varied in the rank order of residual-P＞NaOH-P＞HCl-P＞NaHCO3-P＞H2O-P. The contents of organic carbon, total nitrogen, total P and available P, the proportions of H2O-P, NaHCO3-P and total extractable P were significantly higher than those of forest land and abandoned land, suggesting that the cultivation and fertilization processes have not only improved the contents of total and bio-available P, but also enhanced soil loss risk on the water environment.

Key words: Lake Hongfeng Watershed; soil; phosphorus; agricultural non-point pollution

EARTH AND ENVIRONMENT Vol. 42, No.6, Tot No.302, 2014, Page 719-725