Effects of 4R nitrogen management on corn silage production

Nitrogen (N) is one of the critical and costliest inputs for corn silage ( Zea mays ) production. Excessive N applications decrease profits for growers via increased cost of production and raise environmental concerns. The four core principles of the 4R nutrient stewardship framework—right source (S), right rate (R), right time (T), and right place (P)—aim to optimize N management. Most previous studies evaluating N management for corn silage only examined one or a few 4R practices. The objective of this study was to evaluate the effect of single‐, two‐, three‐, and four‐way combinations of 4R N treatments on corn silage yield and forage nutritive value in Kimberly, ID. Eighteen treatments (nonfertilized control [NFC], grower standard practice [GSP], low, and 15 combinations of 4R N practices) were arranged in a randomized complete block design and replicated four times over three growing seasons (2020, 2022, and 2023). The results showed that N treatments with lower rates produced statistically equivalent yields and crude protein (CP) concentrations as the high‐N GSP (247–353 kg N ha −1 ). Further, combinations of multiple 4Rs may not consistently improve performance over simpler strategies. Thus, growers can maintain comparable productivity while applying considerably less N. However, N rate was important for corn silage in 2022, as evidenced by a linear increase in yield and CP as N rate increased, highlighting substantial year‐to‐year variability. Thus, strategic 4R N management can sustain yield and CP concentration but needs year‐to‐year refinement in Idaho's irrigated corn silage production.