太湖典型地区蔬菜地土壤磷素淋失风险

Risk of phosphate leaching loss from soil of vegetable plot in the typical region of Taihu Lake

以太湖典型地区宜兴市大浦镇湖滨公路以东沿太湖50hm2老蔬菜基地为研究对象,采用网格法(50m×50m)采集表层(0～20cm)土壤样品156个.地统计学分析表明:土壤P(全P、Bray P、CaCl2浸提水溶P)呈明显空间变异,土壤高P区出现在朱渎港、林庄港两村庄附近.土壤Bray P低于60mg·kg-1,几乎没有检测到CaCl2浸提水溶P,而当土壤速效P大于60mg·kg-1后,CaCl2浸提水溶P随Bray P增加而直线增加.以土壤Bray P含量60mg·kg-1为研究地土壤发生P淋溶的临界值,研究范围内土壤发生P淋溶面积占总调查面积28%.针对目前土壤状况,提出控制蔬菜地P淋溶对策.

In this investigation, 156 top layer soil samples (0～20 cm) were taken in a regular grid of 50 m by 50 m at 50 hm^2 area of vegetable plot located at the east part of Taihu road in Dapu town, Yixing city. Geo-statistics analysis of these data demonstrated that spatial variability of soil total P, Bray-P, CaCl_2 extractable P were obvious, and the high-P fields appeared at the shores of Zhudu, and Linzhuang harbors. The CaCl_2 extractable P was very little from soils below 60mg·kg^(-1) Bray-P (termed the Change-Point), however, CaCl_2 extractable P was linearly related to the soil Bray-P. When above the Change-Point we therefore suggested that the Change-Point of around 60 mg·kg^(-1) Bray-P was a critical concentration at which leaching of P happened in vegetable soil. About 28% of the investigation area were at, or above, the Change-Point of 60mg·kg^(-1) Bray-P, and had a risk of P leaching loss from soil to water. Some controlling measures of leaching loss of P to water were also recommended.