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一般认为,氮肥趋于降低苜蓿产量、植被组成和缩短寿命,并刺激杂草侵入。同时,苜蓿能通过共生根瘤菌进行固N_2,故此苜蓿一般不施用N肥。但近几年来也有研究表明,N肥能提高苜蓿的产量,改善其品质,并与苜蓿根瘤数和固N_2能力有关。另外,随着除草剂的应用和发展,似乎应该重新估价N肥对苜蓿的作用。
It is generally accepted that nitrogen fertilization tends to reduce alfalfa yield, vegetation composition, and shortened lifespan, and stimulate weed intrusion. At the same time, alfalfa can solidify N_2 by symbiotic rhizobia, so alfalfa generally does not use N fertilizer. However, studies have shown in recent years that nitrogen fertilizer can increase the yield of alfalfa and improve its quality, and is related to the number of nodules and the ability of fixing N_2. In addition, with the application and development of herbicides, it seems that the effect of N fertilizer on alfalfa should be re-evaluated.