Cropping Systems Influence Yield, Protein Concentration and Nitrogen Use Efficiency of Wheat.

Appropriate cropping systems is not only required but also commendable to contribute to system sustainability. We evaluated different cropping systems containing crop rotation, tillage and nitrogen sources and rates on gran yield, protein concentration and nitrogen use efficiency of winter wheat (Triticum aestivum L.). The experiment was carried out at central Montana in split-split-split plot design. Main plots were crop rotation, sub-plots treatments were tillage and sub-subplots treatments were factorial combination of N sources and rates. Crop rotation includes fallow-wheat, dry pea-wheat and camelina-wheat. Conventional and sweep till were two tillage treatments. The nitrogen sources were regular urea and SuperU® at 0, 45 and 90 kg N ha^-1. Both phases of the rotations were present in each year to avoid confounding effect. Statistical analysis results from GLM of SAS revealed that precursor crops and N-rates significantly affect grain yield, protein concentration and protein harvest of wheat. The grain yield of wheat following fallow, dry pea and camelina were 2657, 2401 and 2283 kg ha^-1, respectively. Application of 45 kg N ha^-1increased grain yield by 25% compared with the unfertilized treatment. The agronomic N use efficiency was higher for no-till compared to sweep till to the extent of 46% particularly at lower N rate. The N sources and most of the interaction effects were not significant.