石灰性土壤中NH_4^+—N的硝化与NH_4^+—N的粘土矿物固定

Ammonium Nitrification and Fixation by Clay Minerals in Calcareous Soil

用杨陵地区红油土的耕层及粘化层(混入1/4耕层土壤)作为2种供试土壤,各设不施,施N,施K,施NK4个处理,在30℃下恒温培养。培养期间分期测定NH^+_4—N,NO^-_3—N及非代换性铵,旨在探讨石灰性土壤中NH^+_4—N的硝化与粘土矿物晶层固定的关系。结果表明,硝化形成的NO^-_3—N以指数曲线递增,NH^+_4—N则以幂函数曲线及反S型曲线递减,最终都达到一个比较稳定的水平。耕层土壤中的NH^+_4—N的硝化作用强烈,被土壤固定量少,粘化层则恰好相反。施入氮肥能显著地增加NO^-_3—N,NH^+_4—N及非代换铵的含量。耕层土壤易固定也易释放固定的NH^+_4—N;粘化层固定后不易释放。施K对减少粘化层NH^+_4—N的固定无明显效果。

Agric horizon and argillitic horizon (with 1/4 agric horizon in it) were used as two soils forincubation experiments at 30℃ withot and with N,K, and NK applications. During the periodsof incubation, NH_4^+ - N,NO_3^- - N and non - exchangeable ammonium were determined atcertain intervals in orderto study the relatioships between ammonium nitrification and fixation byclay ninerals. The results show that NO_3^- - N formed by nitrification was increased byexponential curves, while NH_4^+ -N decreased by power function curves or opposite S curves andfinally reached stable levels. The nitrification in agric horizon was strong, and ammoniumfixation by soil wasless as compared with argillitic horizon. Application of N fertilizers couldsignificantly increase the contents of NO_3^- - N, NH_4^+ - N and nonexchangeable ammonium.Agric horizon could easily fix ammonium and release the fixed, while argillitic horizon could noteasily release the ammonium after fixation. There was no obvious effects on reducing NH_4^+ -Nfixation in argillitic horizonby applying K.