13种土壤硝化过程中亚硝态氮的累积与土壤性质的关系

通过室内培养（土壤水分60％WHC，温度25℃）方法对不同土壤（13种）硝化过程中亚硝态氮的累积进行了研究，并用通径分析方法探讨了土壤亚硝态氮峰值浓度和累积总量与土壤性质的关系，为加强氮素管理、减少亚硝态氮的累积提供理论依据。结果表明，在培养过程中，各供试土壤亚硝态氮的峰值浓度相差较大，且均出现在施肥5-7d，以褐土最高为146．09mg·kg^-1，其次是淤灌土为114．03mg·kg^-1；黑土、黄壤和棕壤在培养过程中几乎未检测到亚硝态氮。亚硝态氮累积总量以褐土、淤灌土最大，分别为350．82和334．51mg·kg^-1；水稻土和砖红壤最小，分别为7．58和13．06mg·k^-1。土壤pH、粘粒、无定形铁通过直接和间接效应成为影响土壤亚硝态氮峰值浓度、累积总量的主要因素，而土壤脲酶活性对这两个因变量的作用均很微弱；就通径分析的直接效应而言，有机质和全氮对土壤亚硝态氮峰值浓度、累积总量的影响最为显著，但其直接效应在很大程度上被其他因素的间接效应所抵消；土壤CEC对土壤亚硝态氮峰值浓度的作用也非常显著。此外，土壤络合态铝、络合态铁虽然对这两个因变量的直接效应不明显，但通过其他因素的综合作用也对这两个因变量起到了一定的影响作用。

Soil Nitrite Accumulation During Nitrification and Its Relationship with Soil Properties in Thirteen Soils of China

The changes of soil nitrite concentration with time were determined during the process of nitrification under urea rate 0.2 g N.kg^-1, moisture content 60 % WHC, and temperature 25 ℃ in the laboratory incubation experiment. The relationship between nitrite peak concentration and nitrite cumulative amount in 13 soils of China and soil properties were calculated by using path analysis. It is necessary to understand mechanisms of soil nitrite accumulation for nitrogen management in ecosystem and environment protection. The result reveled that there were significant difference among nitrite peak concentration from different soils, and it appeared 5 -7 days after urea application in the incubation. Among 13 tested soils, the biggest nitrite peak concentration was from drab soil（ 146.09 mg·kg^-1）, the next one was colmatage soil （114.03 mg·kg^-1）, there was nearly no any nitrite was found in black soil, yellow soil and brown soil. Total nitrite cumulative amount were 350.82 mg·kg^-1 and 334.51 mg·kg^-1 for drab soil and colmatage soil, respectively; and the smallest cumulative amount were paddy soil and lateritic soil. Statistics showed that soil pH, clay grain and amorphous iron content were the major factors influencing the maximum and total nitrite amount in soil due to their effects on soil nitrification, while the urease activities had the least influence on them. With respect to direct affect in the path analysis, soil organic matter and total nitrogen content had most significantly influence on peak and total cumulative nitrite amount. But the direct effects of soil organic matter and total nitrogen content on peak nitrite concentration, total cumulative nitrite amount were to a large extent counteracted by the indirect effects of other factors on them. Soil CEC also significantly influenced on nitrite peak concentration, while coordinative aluminum and coordinative iron were also played an important role on it.