三峡水库新政小流域土壤无机磷的有效性及流失风险研究

Assessment for Soil Inorganic Phosphorus Effectiveness and Phosphorus Loss Risks in Xinzheng Watershed in Three Gorges Reservoir Area

采用蒋-顾土壤无机磷形态分级方法,研究了新政小流域典型作物利用背景下无机磷的空间分布状况及其有效性,并对该区域进行了磷素流失风险评估。结果表明:(1)新政小流域土壤磷素以无机磷为主,占土壤全磷的37%～92%,平均值为69.4%,Ca-P含量占无机磷含量的66.73%～94.09%,平均80.80%。(2)比较了各组无机磷对有效磷的相对重要性,Ca2-P>Al-P>Ca8-P>Fe-P>Ca10-P>O-P。说明Ca2-P是该小流域有效磷的主要来源;(3)以土壤有效磷临界值(60.87mg/kg)为界,不同类型土壤磷素流失风险为:果林地>旱田>消落带>水田。果林地流失风险最高,旱田部分样品超过临界值,而水稻田流失风险最小。

Using Jiang-Gu inorganic phosphorus classification method for soils,this paper investigates distribution of inorganic phosphorus and available phosphorus amount in the soils ,further more, the author assesses the phospho- rus loss risk in the typical agriculture lands in small watershed area of Xinzheng. The results show that： （1） the phosphorus in soils took the form of inorganic P, which accounted for 37% to 92%, and 69.4% on average, the composition of Ca-P accounted for 66.73 %~ 94.09 % in inorganic phosphorus, averaged 80. 800/00; （2） comparing the groups Inorganic phosphorus on the relative importance of phosphorus, Ca2-P〉Al-P〉Ca8-P〉Fe-P〉Ca10-P〉O-P presented predominant source of available P ; （3） taking the sector of soil available phosphorus （60.87 mg/kg） as a limit, different types of soil phosphorus loss risks registered as follows： the fruit forest〉 drought tin〉 fluctuating zone〉 paddy fields. While the fruit forest proved to pose the highest loss risk , and some samples test from dry field exceeded the critical value, while rice fields appeared to have least loss risk.