施肥及刈割对干旱地区紫花苜蓿产量和品质的影响

在黄土高原中部干旱区采用随机区组试验,研究3个施氮水平(0、51.75、103.5 kg·hm^-2)和3个磷水平(0、126、252 kg·hm^-2)下不同刈割次数(3、4次)对“甘农3号”紫花苜蓿种植当年和第2年产量、株高、再生速度及品质的影响,并对紫花苜蓿生长两年中各指标进行比较.结果表明:干旱地区“甘农3号”紫花苜蓿在具备灌溉条件下,种植当年施肥可显著提高产量、株高和再生速度,且4次刈割下显著高于3次刈割;施肥也能增加紫花苜蓿粗蛋白含量,降低中性洗涤纤维和酸性洗涤纤维含量,4次刈割下品质更好;高氮低磷处理(N 103.5 kg·hm^-2+P₂O₅ 126 kg·hm^-2)下效果最好,单施氮肥较单施磷肥效果好.同时,第2年紫花苜蓿产量显著高于第1年,第1年增幅较第2年明显,说明在试验地区,“甘农3号”紫花苜蓿种植当年施肥更有效,第2年施肥仍有益;在灌溉和配施N103.5 kg·hm^-2+P₂O₅ 126 kg·hm^-2条件下,种植当年即可实现4次刈割.

Effects of Nitrogen and Phosphorus Addition and Cuttings on Yield and Quality of Alfalfa in Dry Region of Gansu,China

A randomized block experiment was carried out in the central arid region of the Loess Plateau to explore the effects of nitrogen (0,51.75,103.5 kg·hm^-2), phosphorus (0,126,252 kg·hm^-2) and cutting times (3,4 mowing) on the yield, plant height and quality of " Gannong No.3" alfalfa. The results showed that: in arid areas, under irrigation, application of nitrogen-phosphorus fertilizer could significantly improve the yield, regeneration rate and quality of the "Gannong No.3" alfalfa in the planting year; and cutting 4 times were better than 3 times. The nitrogenous fertilizer and phosphate fertilizer had increased the content of crude protein, decreased in the detergent fiber and acid fiber content of alfalfa. mow cut four times had better quality. They all had better effect on the treatment of low phosphorus, high nitrogen (N 103.5 kg·hm^-2+P₂O₅ 126 kg·hm^-2). The effects on nitrogen fertilizer were stronger than that of phosphate fertilizer. Meanwhile, the yield of alfalfa in second year was significantly higher than that of the first year, and the amplitude of first annual increase significantly over the second year. So, in the test area, it was more effective to apply fertilizer on "Gannong 3" alfalfa in planting year, and the second year was still valuable. It can mowing four times in the planting year under fertilizer combination N 103.50 kg·hm^-2+P₂O₅ 126 kg·hm^-2.