浇施沼液对狼尾草植株硝酸盐累积及其氮素利用效率研究

Efficiency of fertilizing biogas slurry on nitrate accumulation and N utilization of Pennisetum

采用土柱栽培法,通过不同氮素水平的沼液浇灌(设N0～N6共7个氮素水平,即每次浇灌折纯氮0,5,10,20,40,80,160kg/hm2,每45d刈割周期浇灌9次),研究浇施沼液对狼尾草植株硝酸盐累积及其氮素利用效率的影响。结果表明,狼尾草植株的硝酸盐含量受沼液中氮素水平的影响较大,二者之间呈正相关。但在高氮肥水平下,牧草各个刈割期的硝酸盐含量均低于硝酸盐有毒限量指标0.25%。另外,随着沼液中氮素水平的提高,牧草蛋白质含量和蛋白质产量逐渐上升,蛋白质含量和蛋白质产量最高值分别达到21.35%和44.09g/盆。对全年牧草生产的氮肥利用率、蛋白质生产效率、氮素生理利用率、氮素农学生产效率和氮肥偏生产力等5个氮素利用效率指标分别表明,随着沼液中氮素水平的提高,氮素利用效率也越低,损失率也越大。从土柱淋溶的氮量分析也表明,氮素淋溶的量随着氮素水平呈明显的加大趋势,其中N5和N6处理全年淋溶的氮量分别达到80.69和312.3mg。此外,N5和N6处理土柱40cm以下土层全氮含量也显著高于N0～N3处理(P<0.05)。综合考虑认为,在1个刈割周期,狼尾草草地消纳的沼液中氮量应低于纯氮360kg/hm2较为合理。

The experiment was conducted on the way of cultivated soil column,which was to study efficiency of fertilizing biogas slurry on nitrate accumulation and N utilization of Pennisetum according to fertilizing different levels N of biogas slurry（seven levels of N that was from N0 to N6 designed were 0,5,10,20,40,80,160 kg/ha of equivalent nitrogen fertilized,9 times for every 45 days of cutting period）.The result showed that N levels of biogas slurry had an effect on the content of Pennisetum nitrate,and the relations between them were positive correlation.In high levels of N fertilizer,however,the contents of Pennisetum nitrate in different cutting periods were all less than 0.25% of toxic limits for nitrate.In addition,content of Pennisetum crude protein and production of CP were going up with the increased levels of N,the maximums were 21.35% and 44.09 g/pot,respectively.Analyzing the efficiency of N utilization,protein,physiological N,agronomic nitrogen and nitrogen partial factor productivity showed that efficiency of N utilization would be lower,and the loss rate would also be larger with the increasing N levels in biogas slurry.N content of soil column leaching analyzed showed that the quantity of N leaching had the trend of going up with increasing N levels,treatment N5 and N6 in one year were 80.69,312.3 mg respectively.In addition,soil total nitrogen content of group N5 and N6 below 40 cm soil layer were also significantly higher than other groups（P0.05）.It was concluded that in one cutting period,the quantity of Pennisetum grassland absorbing N in biogas slurry was lower 360 kg/hm2 of pure nitrogen,which should be reasonable.