Perenniality drives multifunctional forage–biomass filter strips’ ability to improve water quality

Abstract

Vegetative filter strip characteristics such as perenniality drive hydrology and subsequent ecosystem services. However, the extent and the potential for forage–biomass crops to improve water quality, provide fodder, and optimize nutrient cycling in multifunctional systems is unknown. We evaluated (a) how species, perenniality, and plant community composition are linked to water quality; and (b) the multiuse forage–biomass potential of filter strips. Whole plots were species [eastern gamagrass ( Tripsacum dactyloides), Kernza [or intermediate wheatgrass ( Thinopyrum intermedium)], silphium ( Silphium integrifolium), switchgrass ( Panicum virgatum), and winter wheat ( Triticum aestivum)], with split‐plots receiving 0 or 5.6 Mg ha ⁻¹ broiler litter. Rainfall simulations were conducted at 5 cm h ⁻¹ (until 30 min of continuous runoff) in summer and fall of 2019 and 2021 with dual forage and biomass harvests occurring 2019–2021. Kernza and silphium had the lowest biomass regrowth after forage harvests relative to native grasses, suggesting they would not be ideal multifunctional forage–bioenergy crops. Among all soil–plant–water variables, canonical correlations indicate poultry litter (.97), and soil phosphorus saturation (.77) were the most influential variables for water quality. Water quality score, F _WQ, which is inversely related to runoff water quality, was lowest for switchgrass (0.03) and greatest ( P ≥ .05) for eastern gamagrass and wheat (1.77 and 3.33, respectively), but not different from Kernza (0.98) and silphium (0.31). Therefore, switchgrass resulted in the best water quality scores and highest forage–biomass yields, with Kernza and silphium also showing promise for reducing sediment and nutrient loads following poultry litter applications in multifunctional filter strip systems.

Core Ideas

• Filter strip characteristics drive surface hydrology and subsequent ecosystem services.

• Greatest multiuse (forage–biomass filter strip) yields occurred for switchgrass.

• Poultry litter applications and soil P saturation were most correlated with water quality.

• Perennial crops (excluding eastern gamagrass) improved water quality.

• Switchgrass had the highest water quality and biomass yields, indicating greatest multiuse filter strip potential.