Potential impact of precision nitrogen management on corn yield, protein content, and test weight

Precision crop management for optimizing yield and quality is important for developing a consistent product for different end uses of grain. This study was conducted to evaluate the potential impact of variable-rate N (VRN) application, hybrid selection, and hybrid-specific N management on corn (Zea mays L.) yield, protein content, and test weight. On-farm experiments were conducted during three site-years in eastern Illinois using a split-plot design, with the main plots consisting of five N rates and the subplots two corn hybrids (Pioneer 33G26 and 33J24). Nitrogen response curves of corn yield and quality were fitted at 19 and 16 within-field locations in Fields 1 and 2, respectively, and the potential impacts of different N management strategies were evaluated. Results indicated that within-field economically optimum N rates (EONR) ranged from 82 to 336 kg N ha^-1, while N rates that would maximize grain quality ranged from 0 to 336 kg N ha^-1. Compared with a uniform-rate N (URN) application of 168 kg N ha^-1, the VRN application at EONR would increase corn yield for hybrid 33J24 while having an inconsistent impact on yield of 33G26, without significantly improving grain quality of either hybrid. Hybrid 33J24 would have higher yield, quality, and economic returns than 33G26 under either URN or VRN application. Hybrid-specific N applications could have either negative or positive impacts on corn yield and protein content, without significantly affecting test weight. These results suggest that selecting the right hybrid(s) was more important and practical than the evaluated precision N management practices for optimizing both corn yield and grain quality during the study site-years.