Corn grain yield and 15N-fertilizer recovery as a function of urea sidedress timing

Abstract Best fertilizer management practices such as adopting the right N sidedress timing can reduce N losses by volatilization, thus, raising N-fertilizer recovery and grain yield. To evaluate ammonia (N-NH3 ) losses, N-fertilizer recovery and grain yield as a function of urea sidedress timing in corn, a field study was conducted during the 2011-2012 and 2012-2013 growing seasons, adopting a complete randomized block design with four replications. Treatments consisted of urea sidedress timing (140 kg N ha-1) at V4, V6, V8, V10, and V12 growth stages, plus a control without sidedress N. The largest N losses by N-NH3 volatilization occurred when urea was applied at V10 or V12 growth stages, reaching losses of 35 and 41 % of the total applied N. Although climatic factors influences N-NH3 volatilization process, crop characteristics such as canopy development also seems to affect N-NH3 losses. Nitrogen application at V4 or V6 growth stages resulted in greater N-fertilizer recovery from urea sidedress, reaching values of 53 %. No increase in corn grain yield was observed with N application at different corn growth stages during the two growing seasons evaluated, most likely due to high N mineralization rates from the soil.

摘要：最优施肥管理措施（如选择合适的氮肥追施时期）可通过减少挥发途径的氮素损失，提升氮肥回收率与玉米籽粒产量。为探究玉米尿素追施时期对氨（N-NH₃）挥发损失、氮肥回收率及籽粒产量的影响，本研究于2011-2012与2012-2013年生长季开展田间试验，采用完全随机区组设计并设置4次重复。试验处理涵盖于玉米V4、V6、V8、V10、V12生育期追施尿素（施氮量140 kg·ha⁻¹）的不同时期处理，另设不追施氮肥的空白对照。当尿素于V10或V12生育期追施时，N-NH₃挥发导致的氮素损失最大，分别达到总施氮量的35%与41%。尽管气候因素会影响N-NH₃挥发过程，但作物冠层发育等农艺性状同样会对氮挥发损失产生影响。于V4或V6生育期追施氮肥时，尿素的氮肥回收率最高，可达53%。在本研究评估的两个生长季中，于不同玉米生育期追施氮肥均未观测到玉米籽粒产量的提升，这一结果大概率归因于土壤较高的氮素矿化速率。