污水灌溉区土壤肥力及酶活性特征研究

通过野外调查和采样分析，研究了石家庄栾城县不同污水灌溉时间（0-52a）和不同层位（0-100cm）耕地土壤肥力及酶活性的分布特征。研究结果表明：与清灌对照点相比，污水灌溉区表层（0-20cm）土壤有机质含量、全氮含量、全磷含量、蔗糖酶活性、脲酶活性和磷酸酶活性、亚表层（20-40cm）蔗糖酶活性、磷酸酶活性和下层（40-60cm）蔗糖酶活性均相对较高，而下层有机质含量、全氮含量和底层（60-100cm）全氮含量均相对较低。4层土壤阳离子交换量和过氧化氢酶活性较对照点均无明显的变化规律。表层土壤全氮含量、蔗糖酶活性和磷酸酶活性、亚表层有机质含量、蔗糖酶活性和磷酸酶活性、下层蔗糖酶活性与污灌时间之间均存在显著相关性沪〈0．05）。上述特征反映了土壤肥力及酶活性对污灌的响应具有明显的层位效应和非同步性，而这些响应是由于污水中的营养物质输入土壤后引发微生物活性提高的“激发效应”所致。

Characteristics of fertility and enzyme activity of soils in sewage irrigated fields

Based on field investigation and sample analysis of soils irrigated with sewage for different irrigation periods （ranged between 0 and 52 years） in Luancheng Town Shijiazhuang City, characteristics of soil fertilities and enzyme activities in different layers with depth from 0 to 100 cm were studied. The results showed that the concentrations of organic matter, total nitrogen, total phosphorus, sucrase, urease and phosphatase in the surface layer （0-20 cm）, the concentrations of sucrase and phosphatase in the subsurface layer （20-40 cm） and the concentrations of sucrase in the lower layer （40-60 cm） in the soils irrigated with sewage were higher than those in the soils irrigated with groundwater, while the concentrations of organic matter and total nitrogen in the lower layer and the concentrations of total nitrogen in the bottom layer （60-100 cm） in the soils irrigated with sewage were lower than those in the soils irrigated with groundwater. The concentrations of cation exchange capacity and catalase in four layers of soils irrigated with sewage had no obvious regulation when compared with the soils irrigated with groundwater. The concentrations of total nitrogen, sucrase and phosphatase in the surface layer, the concentrations of organic matter, sucrase and phosphatase in the subsurface layer and the concentrations of sucrase in the lower layer were significantly correlated in a positive manner with irrigation time （P〈0.05）. The results indicated that the response of soil fertility and enzyme activity to sewage irrigation could have significantly vertical and non-synchronous effects, and this response was due to a ＂priming effect＂ that nutrients from sewage irrigation enhanced microbial activity in the soil.