Spring Wheat Yield and Quality Related to Soil Texture and Nitrogen Fertilization

Efficient N fertilization is crucial for economic wheat (Triticum aestivum L.) production and is of great agronomical and environmental significance. A study was conducted at 12 site-years in eastern Canada to evaluate the effect of soil surface textural groups, N rate (0-200 kg N ha(-1)) and application timing on grain yield (GY), N uptake, nitrogen uptake efficiency (NUE), grain protein content (GPC), test weight, and thousand kernel weight (TKW). Chlorophyll meter readings (CMR) were taken at tillering and at flowering to assess in-season wheat N nutrition. Fertilization and soil textural group effects were significant on all measured parameters and their interaction was significant on GPC, TKW, test weight, and CMR. Total N uptake and GPC ranged from 39 to 96 kg N ha(-1) and from 13 to 18 g kg(-1), respectively, and total N uptake increased proportionally to N rates. Applying N levels >120 kg N ha(-1) did not increase total yield, test weight, TKW, or CMR values. The variation in GY, N uptake, and GPC explained by the relative CMR taken at flowering was 87, 88, and 73%, respectively. This study demonstrates that in-season wheat N nutrition can be monitored by CMR and that surface soil texture is an important parameter that influences wheat N response and wheat quality parameters. Applying half of the recommended rate (120 kg ha(-1)) at planting and the rest at tillering resulted in a high total yield, high grain N uptake, and the highest GPC price premium.