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： 采用适宜的氮肥追施时期等最优肥料管理措施，可通过抑制氮素挥发损失提升氮肥回收率与玉米籽粒产量。为评估玉米尿素追施时期对氨态氮（N-NH3）损失、氮肥回收率及籽粒产量的影响，本研究于2011-2012及2012-2013生长季开展田间试验，采用完全随机区组设计，设置4次重复。试验处理包含施氮量为140 kg N ha⁻¹的尿素追施时期处理，分别设置于玉米V4、V6、V8、V10及V12生育期，另设不追施氮肥的对照组。结果表明，当尿素于V10或V12生育期施用时，N-NH3挥发造成的氮素损失最高，分别达总施氮量的35%与41%。尽管气候因素会影响N-NH3挥发过程，但作物冠层发育等性状似乎也会对氮素挥发损失产生作用。在V4或V6生育期施氮可获得更高的尿素追施氮肥回收率，最高可达53%。在本研究评估的两个生长季中，不同生育期施氮均未使玉米籽粒产量出现提升，这极有可能是由于土壤具有较高的氮矿化速率所致。