摘要
本文报道利用^(15)N同位素稀释法研究供给少量化合态氮素对单、混作苜蓿同氮贡献之影响和牧草对土壤氮素的吸收利用和贡献。合理施入化合态氮肥能提高苜蓿固氮能力,延长固氮高峰的持续时间。特别是对初建或低供氮能力的草塌,施入化合态氮肥尤为必要。混播情况下,发生明显的固氮产物转移。豆科牧草的固氮产物似乎比土壤氮素更易为禾本蓿牧草吸收利用。种植苜蓿能明显提高土壤氮肥力。牛尾草可能具有固氮能力。少量化合态氮素的施入对种植苜蓿牛尾草的土壤氮素肥力的提高有明显的促进作用。
This paper reported the study on the effect of combined N applied at low level on the nitrogen fixation by alfalfa in monoculture and mixed culture with meadow rescue, and the effect on the absorption and utilization of indigenous soil nitrogen and nitrogen fertilizer. Amount of nitrogen fixed by alfalfa could be raised and duration of high peak of symbiotic nitrogen fixation activity could be extended when nitrogen fertilizer was applied reasonably. It was especially important for the early pastures or pastures with low supporting nitrogen capacity. Transfer of nitrogen fixed by alfalfa to meadow rescue occured in mixed culture. Nitrogen fixed from alfalfa was uptaken more easily than indigenous nitrogen in soil. planting alfalfa could raise soil fertility significantly. Meadow rescue may be able to fix nitrogen from the air in some way. When combined N was appropriately applied to soil, on which alfalfa and meadow fescue had been planted, it could promote increasing nitrogen fertility in soil.
出处
《同位素》
CAS
北大核心
1990年第2期79-85,共7页
Journal of Isotopes
