Jean-Luc Herman

Uptake and efficiency of split applications of nitrogen fertilizer in winter wheat

In Belgium, nitrogen fertilizer (140–220 kg N ha-1) is applied to winter wheat in split applications at growth stages GS25, 30 and 37. The aim of this work was to compare the efficiency of the last application (GS37) with that of the preceding ones (GS25 and 30) and to measure the uptake of applied N using 15N. Increasing the rate of the GS37 application from 20 to 100 kg ha-1 N raised grain yield by 1000 kg ha-1; efficiency remained almost unaffected (31 kg and 26 kg grain per kg N, respectively), while N recovery in whole plant was highest (77.5%) at 100 kg ha-1, as was grain quality. Conversely, increasing the rate of application at GS25 did not affect yield, and N efficiency plummeted (from 21 kg to 12 kg).