LAUSR

Information on how forage species influence sediment and nutrient transport in runoff is required for limiting non-point source pollution from broiler litter applications. In this study, we examined effects of five forage species [eastern gamagrass (Tripsacum dactyloides), Kernza (Thinopyrum intermedium), silphium (Silphium integrifolium), switchgrass (Panicum virgatum), and winter wheat Triticum aestivum)] on runoff nutrient losses from broiler litter amended (5.6 Mg ha-1 ) and non-amended plots (control) following four simulated rainfall (5 cm h-1 ) events that were applied to these plots in late Spring and early Fall of 2019 and 2021. Runoff collected for 30 min was analyzed for total suspended solids (TSS) and nutrients [total organic carbon (TOC), soluble reactive phosphorus (SRP), total dissolved phosphorus (TDP), total phosphorus (TP), total nitrogen (TN), ammonium-nitrogen (NH4 -N), and nitrate-nitrogen (NO3 -N)]. Total sediment and nutrient losses increased 5 - 19-fold following litter application for all species, which reduced to background levels during fall rainfall events. Across the four simulated rainfall events, switchgrass resulted in lower cumulative losses of TSS, TOC, SRP, TDP, TP, and NO3 -N than gamagrass and wheat, but did not differ from Kernza and silphium for litter amended treatments. The performance of newly introduced perennial crops, Kernza and silphium, were similar or better than that of gamagrass in terms of cumulative runoff sediment and nutrient losses. Results show high potential for Kernza and silphium to improve water quality when used in forage-vegetative filter strip systems. Nutrient concentrations in runoff from forage species are largely affected by runoff rates. Greatest runoff cumulative losses of nutrients and sediment occurred under litter-amended wheat. Following litter additions, switchgrass, Kernza, and silphium had lowest nutrient losses relative to wheat. Newly introduced perennial crops have high potential to provide water quality benefits. This article is protected by copyright. All rights reserved.