|CAVADINI, JASON - University Of Wisconsin|
Submitted to: Forage Focus
Publication Type: Popular Publication
Publication Acceptance Date: 3/1/2023
Publication Date: 3/15/2023
Citation: Cavadini, J., Akins, M.S. 2023. The feasibility of managing Italian ryegrass as a replacement for alfalfa. Forage Focus. March 2023.
Technical Abstract: Italian ryegrass use by Wisconsin dairy farms is increasing due to its high forage quality, good yield potential, and ability to grow in cool/wet conditions. A main issue observed in managing Italian ryegrass is nitrogen fertilization and the potential to overapply fertilizer to gain yield and protein value. Work was conducted at the University of Wisconsin Marshfield Agricultural Research Station (Stratford, WI) to evaluate seven rates of nitrogen fertilizer (0, 30, 60 (as urea or urea ammonium nitrate), 90, 120 lb N/acre and surface applied liquid manure (40 lb N/acre); 4-5 applications/year) on Italian ryegrass yield and quality over three years. Yield increased with additional nitrogen fertilizer but had reduced responsiveness at rates above 60 lb N/acre (300 lb N/acre/year). Fiber and fiber digestibility was not affected by additional nitrogen, however crude protein was increased with additional nitrogen fertilizer but only from 15% at 0 lb N to 19% at 60 lb N to 22% at 120 lb N/acre. The 90 and 120 lb N/acre rates resulted in severely decrease nitrogen use efficiency and thus increased soil nitrate levels which can result in leaching and groundwater contamination. Use of liquid manure provided yields and quality similar to 30 lb N/acre/harvest and could be used as a sole nitrogen source, however injecting the manure likely would improve its nutrient use efficiency. Based on this work, nitrogen fertilizer rates of 30-60 lb N/acre for each harvest appears to optimize forage yield and protein value but additional economic analysis is needed to determine the optimal rate.