Nitrogen（N） is one of the macronutrients required for plant growth, and reasonable application of N fertilizers can increase crop yields and improve their quality. However, excessive application of N fertilizers will decrease N use efficiency and also lead to increases in N2O emissions from agricultural soils and many other environmental issues. Research on the effects of different N fertilizer management practices on wheat yields and N2O emissions will assist the selection of effective N management measures which enable achieving high wheat yields while reducing N2O emissions. To investigate the effects of different N management practices on wheat yields and soil N2O emissions, we conducted field trials with 5 treatments of no N fertilizer（CK）, farmers common N rate（AN）, optimal N rate（ON）, 20% reduction in optimal rate＋dicyandiamide（ON80%＋DCD）, 20% reduction in optimal rate＋nano-carbon（ON80%＋NC）. The static closed chamber gas chromatography method was used to monitor N2O emissions during the wheat growing season. The results showed that there were obvious seasonal characteristics of N2O emissions under each treatment and N2O emissions were mainly concentrated in the sowing-greening stage, accounting for 54.6–68.2% of the overall emissions. Compared with AN, N2O emissions were decreased by 23.1, 45.4 and 33.7%, respectively, under ON, ON80%＋DCD and ON80%＋NC, and emission factors were declined by 22.2, 66.7 and 33.3%, respectively. Wheat yield was increased significantly under ON80%＋DCD and ON80%＋NC by 12.3 and 11.9%, respectively, relative to AN while there was no significant change in yield in the ON treatment. Compared with ON, overall N2O emissions were decreased by 29.1 and 13.9% while wheat yields improved by 18.3 and 17.9% under ON80%＋DCD and ON80%＋NC, respectively. We therefore recommend that ON80%＋DCD and ON80%＋NC be referred as effective N management practices increasing yields while mitigating emissions.
LIU Ya-nanLI Ying-chunPENG Zheng-pingWANG Yan-qunMA Shao-yunGUO Li-pingLIN Er-daHAN Xue
为减少土壤N_2O排放,提高作物氮素利用,采用田间试验法研究了不同氮肥用量喷涂一定比例的吡啶(0、180、270、360 kg N·hm^(-2))对夏玉米生育期内土壤N_2O排放和氮素表观损失、籽粒产量及氮素利用的影响.结果表明:不同氮肥用量下喷涂吡啶的土壤N_2O排放主要集中在播种-苗期和拔节-抽雄期,基肥和追肥后均会出现显著的土壤N_2O排放通量高峰.随氮肥用量增加,玉米产量不断增加,但270和360 kg N·hm^(-2)间无显著差异,2种施氮量下的玉米分别净增收5209和5426元·hm^(-2).与不施氮肥比,各施氮处理下的玉米籽粒吸氮量提高幅度为109.6%~134.1%.各处理间的氮肥农学效率和氮肥利用率均以氮肥喷涂吡啶270 kg N·hm^(-2)较大,而土壤氮素表观损失较小.氮肥喷涂吡啶在270 kg N·hm^(-2)时玉米增产增收,氮肥利用效率较高,土壤N_2O排放和氮素表观损失较少,是一种较为合理的氮肥调控施用技术.
