Soybean flour as an alternative plant‐based fertilizer for perennial ryegrass ( Lolium perenne L.) and tall fescue [ Schedonorus arundinaceus (Schreb.) Dumort] lawns

Demand for organic fertilizers has prompted the exploration of different sources of sustainable, plant‐based alternatives for turfgrass lawns. This study evaluated defatted soybean flour as a potential plant‐based fertilizer option for high‐cut turfgrass systems such as lawns, parks, recreational facilities, and commercial landscapes when applied as a powder, drench, or spray to perennial ryegrass ( Lolium perenne L.) and tall fescue [ Schedonorus arundinaceus (Schreb.) Dumort]. The fertilizer response of soybean flour was compared to corn gluten meal (CGM) and untreated controls in greenhouse and field experiments in Wooster and Columbus, OH, and West Lafayette, IN. In a greenhouse, soybean flour was applied as a powder in a proof‐of‐concept experiment, which resulted in positive dose‐dependent turfgrass responses, with an optimal nitrogen rate between 19.5 and 29.3 kg N ha − 1 . Staged‐up proof‐of‐concept field trials in which soybean flour was drenched on turfgrass plots confirmed these greenhouse findings. Unlike CGM, which showed a gradual improvement in turfgrass quality when applied to field plots, soybean flour produced more rapid initial growth responses from 7 to 14 days post application. Following initial proof‐of‐concept experiments, soybean flour was sprayed on turfgrass plots, in which turfgrass growth and other parameters increased with soybean flour application compared to untreated controls. The results suggest that soybean flour could be a viable plant‐based fertilizer for high‐cut cool‐season lawns, offering comparable performance to CGM, with potential for broader adoption in environmentally conscious turfgrass management. Future work should focus on refining application methods and nutrient release profiles to improve practicality and consistency for industry and homeowner use.