磷肥和钾肥对老龄多叶老芒麦牧草生物量和品质的影响

对8龄多叶老芒麦人工草地进行施磷、钾试验。结果显示，施磷肥对抽穗期、开花期和乳熟期老芒麦的地上生物量分别增重16.25%~50.32%、5.86%~35.74%和10.72~44.37%，施钾肥增重16.96%~51.56%、9.63%~58.32%和12.70%~46.91%。在氮钾或氮磷施量适中时，配施磷肥112.5 kg/hm2或配施钾肥75 kg/hm2时，老芒麦的地上生物量最大。配施磷和钾能显著增加老芒麦025 cm根重（P＜0.05）。配施磷或钾75 kg/hm2时，老芒麦05和025 cm根重最大，分别为8.97 g/m2、9.06 g/m2和21.39 g/m2、23.84 g/m2。配施磷和配施钾时，老芒麦茎秆中粗蛋白（CP）和粗脂肪（CF）含量呈先增后降变化，施磷75 kg/hm2或施钾112.5 kg/hm2时，老芒麦茎杆中CP和CF的含量最大。配施等量磷、钾肥，施磷茎秆中CP和CF含量高于施钾，二者最大值差分别是0.53%和0.38%。三个生育期内，老芒麦地上部分与地下根系增重不总是与施肥量呈正相关，相同施肥量下钾肥的增重略高于磷肥。

Effect of fertilization on the forage biomass and quality of aged leafy Elymus sibiricus

Under the conditions of sufficient N, P and K fertilization, growth index including aboveground biomass, dry root weight at different growing period and forage nutritional indexes, such as DM, CP, CF and CF at milky maturity stage of 8a Elymus sibiricus were measured in an artificial grassland on May in 2003 at well-bred site in Qinghai Province. The results showed that P and K fertilization increased the aboveground biomass of E. Sibiricus by 16.25 % -50.32%, 5.86%-35.74%, 10.72%-44.37%, and 16.96%-51.56%, 9.63%-58.32%, 12.70%-46.91% at heading date,flowering period and milky maturity stage, respectively. At the rational level of NK or NP, the maximum aboveground biomass was observed when additional P 112.5 kg/ha or K 75 kg/ha was applied. Applying both P and K could increased the roots weight in 0-25 cm significant ( P < 0.05). The root weight in depth of 0-5 cm and 0-25 cm of E. Sibiricus was maximum when additionally applying P or K 75 kg/ha. The con.tent of CP and CF increased first then decreased after application of P and K. Applying P 75 kg/ha or K 112.5 kg/ha resulted in the highest the content of CP and CF in the stem. The weight increased of biomass of aboveground and roots did not consistently positive correlation to the quantity of fertilizer application. The weight increased with potassium fertilizer was higher than phosphorus fertilizer at the same fertilizer level.