氮肥水平对豆禾混播草地产量和营养品质的影响

Effects of Nitrogen Fertilizer Levels on Yield and Quality of Legume-Grass Mixtures

【目的】探讨四川湿热地区豆禾混播草地的适宜施氮水平,为该区豆禾混播草地施用氮肥提供理论依据。【方法】以该区建植的紫花苜蓿(Mediccago sativa L.)、白三叶(Trifolium repens L.)、鸭茅(Dactylis glomerata L.)和苇状羊茅(Festuca arundinacea Schreb.)混播草地为材料,设N_(1)(低氮,150 kg/hm^(2)纯氮)、N_(2)(中氮,300 kg/hm^(2)纯氮)和N_(3)(高氮,450 kg/hm^(2)纯氮)3个氮素水平,研究不同氮素水平下混播草地产量和营养品质。【结果】豆禾混播草地年平均干草产量随施氮量增加而增加,N_(3)处理干草产量最高,达13.80 t/hm^(2),较N_(1)和N_(2)处理分别高37.45%和9.18%(P<0.05)。牧草粗蛋白(CP)含量和相对饲喂价值(RFV)随施氮量的增加而增加,4茬刈割中N_(3)处理CP含量较N_(1)处理分别高3.64%、8.36%、10.67%和12.08%(P<0.05);N_(3)处理的相对饲喂价值最大,为157.35;酸性洗涤纤维(ADF)和中性洗涤纤维(NDF)平均含量随施氮量增加而降低,处理间差异显著(P<0.05)。【结论】氮肥显著提高了豆禾混播草地产量并改善营养品质,采用隶属函数值法综合评价进一步得出,450 kg/hm^(2)纯氮处理时豆禾混播草地产量和营养品质最佳。

【Objective】To investigate the appropriate nitrogen level of legume-grass mixtures in the hot and humid areas of Sichuan province,and to provide a theoretical basis for the application of nitrogen fertilizer to legume-grass mixed grassland in this region.【Method】In the mixtures of alfalfa,white clover,orchardgrass,and tall fescue,3 nitrogen levels:N_(1)(low nitrogen,150 kg N/hm^(2) pure nitrogen),N_(2)(medium nitrogen,300 kg N/hm^(2) pure nitrogen),and N_(3)(high nitrogen,450 kg N/hm^(2) pure nitrogen)were applied to study the effect of nitrogen level on the biomass yield and nutritional quality.【Result】The results showed that hay yield was increased with the increase of nitrogen,N_(3) had the highest yield(13.80 t/hm^(2)),which was 37.45%and 9.18%higher than those of N_(1) and N_(2),respectively(P<0.05).The content of crude protein(CP)and relative feeding value(RFV)was increased with the increase of nitrogen level.The CP of N_(3) was 3.64%,8.36%,10.67%and 12.08%higher than that of N_(1) in the four times of mowing,respectively(P<0.05),while the content of RFV was the highest(157.35).The average of acid detergent fiber(ADF)and neutral detergent fiber(NDF)was decreased with the increase in nitrogen level,respectively(P<0.05).【Conclusion】Nitrogen fertilizer can significantly increase the yield of legume-grass mixtures and improve the nutritional quality.Through comprehensive analysis by the membership function method,the 450 kg N/hm^(2) was the optimal in both yield and nutritional quality.