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采用PVC管原位培养法,研究了苹果园行间生草,肇东苜蓿(Medicago sativa‘Zhaodong’)和老芒麦(Elymus sibiricus)对土壤氮素净矿化作用及物候期间的变化特征,并进一步分析净硝化作用和净氨化作用特征及其与土壤因素之间的关系。结果表明:土壤氮素矿化作用主要以硝化作用为主,氨化作用比重很小。测试期间,0~15 cm土层中,自然生草土壤的氮素净硝化速率为0.30 mg·kg-1·d-1,老芒麦土壤为0.68 mg·kg-1·d-1,苜蓿土壤最低,为0.28 mg·kg-1·d-1。不同草种的氮素矿化主要在开花期完成,苜蓿土壤中开花期的土壤氮素净矿化速率分别为营养期和果实期的3.4倍和1.6倍,老芒麦则分别为1.8倍和3.0倍。老芒麦土壤中C/N比影响着氮素硝化能力,15~30 cm土层土壤的氮素矿化相对较弱。种植老芒麦后土壤氮素矿化能力明显提高,而苜蓿土壤中硝化速率降低。
In this study, the net nitrogen mineralization of alfalfa or Medicago sativa’Zhaodong ’and Elymus sibiricus in apple orchard during the phenological period was studied by in situ culture of PVC tube. And further analysis of net nitrification and net ammonification characteristics and its relationship with soil factors. The results showed that the main mineralization of soil nitrogen was nitrification, and the proportion of ammoniation was small. In the 0-15 cm soil layer, the net nitrification rate of N. mongolica was 0.30 mg · kg-1 · d-1 and the soil was 0.68 mg · kg-1 · d-1, The lowest soil concentration was 0.28 mg · kg-1 · d-1. Nitrogen mineralization of different grass species was mainly completed in the flowering stage. Net nitrogen mineralization rates of flowering stage in alfalfa soil were 3.4 times and 1.6 times higher than those in vegetative stage and fruit stage, respectively, 3.0 times. The C / N ratio of Simenngmao sativa affects the ability of nitrogen nitrification, and the nitrogen mineralization in the soil of 15-30 cm soil layer is relatively weaker. The soil nitrogen mineralization ability of S. mongolica increased significantly after planting S. millet, while the nitrification rate of alfalfa soil decreased.