北京低山区森林土壤硝化和反硝化作用的研究

应用土壤培养法和硝酸盐消失法对北京低山区森林土壤的硝化和反硝化作用分别进行了研究．结果表明：①森林土壤有较强的硝化活性，且表土层比底层土强，同时根际土利于硝化作用进行，根际效应Ｒ／Ｓ在４５左右；②淹水厌气培养２４ｈ，ＮＯ－３ Ｎ的消失率为５２％～５８％，占第１０天的５５％～７１％，且表土层ＮＯ－３ Ｎ的消失率比底层土大；③参与同化反硝化作用的还原酶活性较强，在培养２４ｈ后，被还原的基质数量占加入基质数量的７０％～９０％．

Nitrification and Denitrification of Forest Soil in Lower Mountains in Beijing

The soil incubation method and nitrate lossen method were applied respectively to study the nitrification and denitrification of the forest soil in lower mountain regions in Beijing. The results show that: ①The forest soils have the stronger nitrification, but also the nitrification in surface horizon is stronger than the undersoil's. At the same time, the rhizosphere is favourable to the nitrification, the rhizosphere effect R/S is about 4.5; ②The loss rate of NO - 3 N in 24h in flooded and anaerobic incubation is 52%～58%, that is 55%～71% of the tenth day, but also the loss rate of NO - 3 N in surface horizon is larger than the undersoil's; ③The reductase activity that related to the assimilative denitrification is stronger. After 24h incubation ,the reduced matrix is 70%～90% of the adding matrix.