Uptake and agronomic efficiency of nitrogen in winter barley and winter wheat.

Nitrogen (N) uptake and utilization efficiency (NUtE) of the high-yielding cultivars ‘Gemini’ of wheat and ‘Jaidor’of barley were tested with N rates of 0, 140 and 210 kg ha−1 and 0, 80 and 140 kg ha−1, respectively. The differentgrain yield response was linked to their difference in nitrogen uptake and utilization efficiency. The highest yield inbarley was recorded with 80 kg N ha−1 and in wheat with 210 kg N ha−1. Nitrogen application affected theaccumulation of biomass up to heading in wheat and barley. While N uptake during grain filling did not show anycorrelation to N applied in barley, it was markedly correlated in wheat. At N0 and N140 N applied, barley exhibiteda 32 and 8% higher NUtE than wheat. N agronomic efficiency, a parameter representing the ability of the plant toincrease yield in response to N applied, was similar in barley and wheat (8.7 and 9.2 kg kg−1 of N applied,respectively), suggesting that both species respond equally to nitrogen fertilization. Nevertheless, due to its lowerNUtE, wheat requires high N fertilization to optimize yields; by contrast, in barley the lower N rate needed to achievehighest yields enables this crop to perform better in low-input conditions. As a results, the reduced N requirementsfor barley highest yield associated with a better RF value (apparent N fertilizer recovery of 63% in barley and 49% inwheat at N140) makes barley crop a better choice to reduce ground-water pollution due to nitrate leaching in winterand early spring.