Early Planting and Optimized Nitrogen Rate Maximize Biomass Sorghum Yield and Profitability

ABSTRACT Nitrogen (N) rate, timing, and source can strongly influence biomass sorghum yield, profitability, and disease risk, yet these management effects remain insufficiently understood under early‐ and late‐planted systems in the Mid‐Atlantic U.S. Two field experiments were conducted from 2017 to 2019 across multiple site‐years to evaluate the effects of planting date, sidedress N rate, and fertilizer source on biomass sorghum yield and related traits. Experiment 1 evaluated sidedress N rates (0–224 kg N ha −1 ) under early planting (EP; a full‐season cropping system) and late planting (LP; mimicking a double‐crop system) and determined the most economic rate of N (MERN). Experiment 2 compared environmentally smart nitrogen (ESN) with upfront and sidedress N applications at 168 kg N ha −1 across planting dates. In experiment 1, EP produced 53% greater dry matter yield and 18% higher plant height than LP, while LP had 8% lower disease severity. A MERN of 57 kg N ha −1 provided the maximum yield, partial factor productivity and N use efficiency. In experiment 2, EP resulted in 66%, 19%, and 26%, higher dry matter, plant height and stem diameter, respectively, than LP. Upfront N and ESN produced similar biomass yield and stem diameter, but upfront N increased disease severity relative to ESN. Overall, EP and application of 57 kg N ha −1 was the most effective strategy for maximizing biomass yield and farm profitability. These findings suggest producers should prioritize planting date and N rate at MERN over fertilizer source, while ESN may offer added benefits under disease‐prone conditions.