施肥水平和刈割制度对鸭茅生产性能的影响

The Effect of Different Nitrogen Application and Cutting Systems on Productive Performance of Orchardgrass

对 1997、1998两年播种量为 2 0kg/hm2 的鸭茅进行播种试验 ,氮肥水平分别是 0 ,37,74,111,148,185kg/hm2 ;刈割频率每年为 2次、3次。氮肥水平增加到 74kg/hm2 时 ,干物质 (DM )产量最高 ,首次刈割推迟 ,刈割周期延长 ,DM产量提高。提早播种对于提高产量有显著影响 ,晚秋 (10月份 )收割会使冬季营养贮备贫乏 ,从而对安全越冬造成威胁。鸭茅总含氮量 2 .5 8% 4.40 % ,在氮肥水平低于111kg/hm2 时 ,含氮量受氮肥水平的影响不大。体外干物质消化率 (IVDMD)受刈割频率的影响较大 ,氮肥水平高于 74kg/hm2 时 ,硝态氮 (NO3 N)积累量超过 0 .15 % 。

The experiments were conducted on the orchardgrass sowed in 1997 and 1998 respectively, with sowing rate of 20 kg/hm 2. Applied nitrogen was 0,37,74,111,148,185 kg/hm 2.Cutting frequency was 2 and 3 times/year. The results show when nitrogen application is 74 kg/hm 2 , dry matter (DM) yield of the grass is highest. The extend first cutting and long cutting interval can improve the DM yield. Early sowing is imperative to get high DM yield. Harvest in late autumn (Oct.) can result in the shortage of nutrients stored and poor survival rate of the grass in winter. The total nitrogen content in orchardgrass range from 2.58% to 4.40%, which is less affected by the nitrogen application when below 111 kg/hm 2 . In vitro dry matter digestibility (IVDMD) is significantly affected by the cutting frequency. When applied nitrogen exceeds 74 kg/hm 2, the nitrate N content in orchardgrass will be above 0.15%, which might be potentially toxic to the livestock consuming this grass.