The Effect of Simulated Distribution of Soil Mineral Nitrogen and Root Traits on Wheat Yield and Grain Nitrogen Concentration

The effect of different distribution of available mineral N (Nmin) in a soil profile, in combination with increasing N fertilization rates, on grain N concentration and yield of winter wheat was studied with the model CERES-wheat. A great proportion of Nmin in a deep subsoil under 90 cm resulted in enhancement of grain N concentration but at the expense of grain yield. Under a high total Nmin supply in rooted soil volume the effect was less. High N fertilization rates almost eliminated the effect of different Nmin distributions. The enhancement of root growth rate and maximum depth by 30% decreased significantly residual Nmin in deep subsoil when total Nmin was high. The modification had no impact on simulated grain N concentration but it increased yields, most remarkably when a great proportion of total Nmin could be found under 90 cm.