肥料运筹对杂交狼尾草氮素利用效率和硝酸盐含量的影响

Effects of Fertilizer Application on Nitrogen Utilization Efficiency and Nitrate Content in Hybrid Pennisetum

在江苏南京地区,研究了肥料运筹对杂交狼尾草氮素吸收利用效率和植株硝酸盐含量的影响。结果表明:施用有机肥67 500 kg/hm2+无机氮肥(纯氮)270.0 kg/hm2处理,杂交狼尾草干物质产量和氮素积累总量均达到最大值,氮素干物质生产效率较低,第3、第4、第5刈次植株硝酸盐含量均高于0.25%,单独饲喂家畜存在硝酸盐中毒的潜在危险;施用有机肥45 000 kg/hm2+无机氮肥(纯氮)270.0 kg/hm2和67 500 kg/hm2+无机氮肥(纯氮)67.5 kg/hm2处理,杂交狼尾草氮素干物质生产效率显著最高,总干物质产量也较高,分别为9 922.3 kg/hm2和9 219.6 kg/hm2,第2、第3、第4刈次植株硝酸盐含量均低于0.25%,饲喂家畜无任何硝酸盐中毒的危险。因此,综合考虑氮素吸收利用效率和植株硝酸盐含量,有机肥45 000 kg/hm2+无机氮肥(纯氮)270.0 kg/hm2和67 500 kg/hm2+无机氮肥(纯氮)67.5 kg/hm2均为杂交狼尾草较适宜的肥料运筹方案。

Effects of fertilizer application on nitrogen utilization efficiency and nitrate content in hybrid Pennisetum was studied in Nanjing, Jiangsu province. The results were showed as follows：dry matter yield and total nitrogen accumulation in hybrid Pennisetum reached the highest and dry matter production efficiency by nitrogen was relatively low as fertilization combination of 67 500 kg/hm^2 manure plus 270.0 kg/hm^2 chemical nitrogen was applied ; at the same time, nitrate content in forage was higher than 0. 25% in second, third and fourth defoliation, which could cause potential nitrate toxic danger when the forage was fed lonely. Nitrogen dry matter production efficiency and dry matter yield were higher than those in other fertilization combinations as 45 000 kg/hm^2 manure plus 270.0 kg/hm^2 chemical N or 67 500 kg/hm^2 manure plus 67. 5 kg/hm^2 chemical N was applied. In the above two treatment, nitrate contents in forage were lower than 0. 25% in the second, third and fourth defoliation which would cause no toxic danger for animal 45 000 kg/hm^2 manure plus 270. 0 kg/hm^2 chemical N and 67 500 kg/hm^2 manure plus 67.5 kg/hm^2 chemical N were regarded as two optimum fertilizer designs for hybrid Pennisetum if nitrogen uptake and utilization efficiency and nitrate content were considered synthetically.