深耕加秸秆还田下施氮量对土壤碳氮比、玉米产量及氮效率的影响

Effects of Nitrogen Application Rate on Soil C/N,Maize Yield and Nitrogen Efficiency under Condition of Deep Tillage and Straw Returning

为明确深耕加秸秆还田条件下的适宜施氮量,研究了深耕加秸秆还田条件下不同施氮量[0、240、270、300(当地生产平均施氮水平)、330、360 kg/hm2N]对土壤碳氮比、玉米产量及氮效率的影响。结果表明,深耕加秸秆还田下增施氮肥可以提高玉米植株干物质和氮素积累量,增加土壤有机质和全氮含量,调节土壤碳氮比,进而提高玉米籽粒产量和氮效率。深耕加秸秆还田条件下,随着施氮量的增加,土壤有机质和全氮含量增加,碳氮比降低;玉米植株干物质积累量、氮素积累量、籽粒产量及氮素农学效率、氮素表观利用率均先增加后降低,以330 kg/hm2处理最高,其籽粒产量、氮素农学效率、氮素表观利用率比当地生产平均施氮水平300 kg/hm2处理分别显著提高9.3%、23.6%、46.7%,但其产量与360 kg/hm2处理差异不显著。表明,深耕加秸秆还田条件下,玉米需适当增加氮肥施用量,试验区玉米适宜氮肥用量以330 kg/hm2(较当地平均施氮水平高10%)为宜。

In order to define the optimum application rate of nitrogen fertilizer,the effects of different nitrogen application rate（ 0,240,270,300,330,360 kg / ha） on soil C / N,maize yield,nitrogen efficiency under the condition of deep tillage and straw returning were investigated. The results showed that,the increase of the application rate of nitrogen fertilizer increased the accumulation amount of dry matter and nitrogen of maize,improved the contents of soil organic matter and total nitrogen,regulated the soil C / N,thus increased the maize grain yield and nitrogen efficiency. Under the condition of deep tillage and straw returning,with the increase of application rate of nitrogen,the contents of soil organic matter and total nitrogen increased,while soil C / N decreased; dry matter accumulation amount,nitrogen accumulation amount,grain yield of maize,nitrogen agronomic efficiency and nitrogen apparent utilization efficiency increased first and then decreased,the treatment with N 330 kg / ha reached the highest values,whichgrain yield,nitrogen agronomic efficiency and nitrogen apparent utilization efficiency increased by 9. 3%,23. 6% and 46. 7% compared with the treatment with the local average nitrogen application rate 300 kg / ha,respectively. However,there was no significant difference in grain yield between the treatment the treatment with N 330 kg / ha and the treatment with N 360 kg / ha. In conclusion,the application rate of nitrogen fertilizer need to be added appropriately under the condition of deep tillage and straw returning,and N 330 kg / ha（ 10% higher than the local average nitrogen application rate） was an optimum application rate of nitrogen for maize in the experimental area.