施氮肥对紫花苜蓿产量及饲用营养品质的影响

Yield and Forage Nutritive Quality Improvement of Alfalfa by Nitrogen Application

采用盆栽方法,研究了不同氮肥用量对紫花苜蓿鲜、干草产量及饲用营养品质的影响。结果表明:在相同磷钾肥条件下,施氮肥可同时提高鲜草与干草产量,除第一茬外,第二、三、四茬,中氮(0.18 g·株-1)比高氮(0.36 g·株-1)对生物量的影响显著,且随收获次数的增加,不施氮(0 g·株-1)处理的鲜、干草产量较施氮下降快;中氮水平较高氮水平更利于提高粗蛋白(CP)、粗脂肪(EE)与粗灰分(CA)含量及产量,降低粗纤维(CF)含量,改善适口性,提高消化率,并增加总能量(GE)的产量;不同氮肥用量对苜蓿饲用营养品质的影响时期不同,中氮水平可以降低收获中期纤维蛋白比,提高饲草饲料的营养品质,高氮水平则利于降低植株初期与收获后期纤维蛋白比,提高饲草营养品质。

The effects of different nitrogen application rate on the yield and forage nutritive quality of alfalfa were studied in an experiment of pot culture. The results showed that under the condition of the same level P and K, the fresh yield and dry yield were both increased by application of nitrogen fertilizer, and the second, the third, the forth harvest stage, the middle nitrogen level （0.18 g· pl-1 ）was more markedly responded than the highest nitrogen level （0.36 g· pl-1 ）except the first harvest stage, and the yield of the lower nitrogen level （0 g· pl-1 ）decreased quickly than the topdressing nitrogen fertilizer. With increasing of clipping times, the middle nitrogen level increased content of crude protein （CP）, ether extract （EE）, crude ashes （CA）, and decreased the crude fiber （CF） , than those of the highest nitrogen level, which improved the forage nutritive quality and the gross energy （GE） of alfalfa. Effects of the different nitrogen level on the forage nutritive quality of alfalfa were embodied in different harvest stage, the middle level reduced the ratio of the crude fiber （CF） and crude protein （CP）, it was reduced by the highest level, and both the middle level and the highest level improved the forage nutritive quality of alfalfa.