LAUSR

Water and nitrogen (N) play an important role in closing the yield gap of crops by reducing associated stresses and yield variability. Field research data coupled to the CSM-CERES-Maize model of Decision Support System Agrotechnology Transfer were used to advance our understanding of the effect of water and N on silage corn growth and yield. The objectives of the study were to determine: (i) the best combination of irrigation water and N for optimum biomass yield, and (ii) the yield gap of silage corn grown at different locations in Wyoming, USA. Field experiments were conducted under sub-surface drip irrigation using a randomized complete block design in a split-plot arrangement with four replications. The main plot was irrigation and consisted of 100% crop evapotranspiration (100ETc), 80% (80ETc), and 60% (60ETc), and the sub-plot was N rates, including 0, 90, 180, 270, and 360 kg N ha −1 as urea-ammonium-nitrate. The simulated results indicated full irrigation and at least 150 kg N ha −1 as the best combination for silage corn production in Wyoming. Our observed and simulated results show the potential to increase the biomass and reduce the yield gap of silage corn in the region if irrigation water and N are properly managed.