氮肥后移对春玉米产量、氮素吸收利用及土壤氮素供应的影响

采用田间试验,研究氮肥后移对春玉米产量、氮素吸收利用、土壤无机氮含量动态变化和氮素平衡的影响。结果表明,氮肥后移各处理两年玉米产量均显著高于100%基肥处理,提高幅度分别为27.0%～51.8%和37.9%～69.4%,其中30%基肥+50%拔节肥+20%开花肥处理玉米产量最高。与100%基肥处理相比,氮肥后移各处理氮素吸收利用率、农学利用率、偏生产力和生理利用率两年依次提高35.8%～49.6%、46.1%～92.2%、9.8%～19.5%、9.4%～24.8%和42.8%～64.2%、51.1%～83.0%、14.3%～22.9%、6.8%～11.7%,差异均达显著水平,且均以30%基肥+50%拔节肥+20%开花肥处理效果最佳。与100%基肥处理相比,氮肥后移各处理在提高玉米开花期至成熟期0～40 cm土壤无机氮含量的同时,降低玉米收获后41～100 cm土壤无机氮含量。

Effect of Postponing Nitrogen Application on the Yield,Nitrogen Absorption and Utilization and Soil Nitrogen Supply in Spring Maize

To explore the reasonable fertilizer application method for spring maize, field experiment was con-ducted to study the effects of postponing nitrogen application, with 100% nitrogen being basal fertilizer as control. The yield, nitrogen absorption and utilization, the dynamic changes of soil inorganic nitrogen and nitrogen balance were evaluated. Results showed that postponing nitrogen application significantly increased maize yield by 27.0%-51.8% in 2105 and 37.9%-69.4% in 2016 compared with control, and the highest maize yield was obtained when 30% of total application nitrogen as basal fertilizer, 50% applied at jointing stage and 20% at flowering stage. Com-pared with control, nitrogen absorption utilization, agronomic efficiency, partial factor productivity and physiological efficiency were respectively increased by 35.8%-49.6%, 46.1%-92.2%, 9.8%-19.5%, 9.4%-24.8% in 2015 and 42.8%-64.2%, 51.1%-83.0%, 14.3%-22.9%, 6.8%-11.7% in 2016 under the management of postponing nitrogen application, and these evaluation indices reached up to the highest levels with 30, 50 and 20% nitrogen applied at sowing, jointing and flowering stages respectively. Using postponing nitrogen application, the inorganic nitrogen con-tent(nitrate nitrogen and ammonium nitrogen) in 0-40 cm soil layer was increased from flowering to maturing stage, while the inorganic nitrogen content in 41-100 cm soil layer was decreased after crop had been harvested.