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

Authors: Ashworth, Amanda; KATUWAL, SHEELA - University Of Arkansas; Moore, Philip; Adams, Taylor; Anderson, Kelsey; Owens, Phillip

Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/1/2022
Publication Date: 11/17/2022
Citation: Ashworth, A.J., Katuwal, S., Moore Jr, P.A., Adams, T.C., Anderson, K.R., Owens, P.R. 2022. Perenniality drives multifunctional forage-biomass filter strips’ ability to improve water quality. Crop Science. 63:336–348. https://doi.org/10.1002/csc2.20878.
DOI: https://doi.org/10.1002/csc2.20878

Interpretive Summary: Beyond selecting pasture crops solely on yield, evaluating their ability to serve as multi-use filter strip (provide forage and biomass) to allow producers flexibility to respond to market variations, as well as prevent nutrient losses should be considered to enhance ecosystem services in the largest land-use category in the U., or grasslands. In this study, researchers tested five species [two native perennial grasses (switchgrass and eastern gamagrass), two newly released perennial species (kernza or perennial wheat and silphium), an an annual, wheat) either receiving annual poultry litter or a no-litter control. Evaluations were made based on forage and biomass yield, composition, and subsequent nutrient runoff and removal. Overall, forage harvests were greatest for silphium, but yields were starkly reduced during fall biomass harvests for silphium and Kernza, suggesting these perennial species are not ideal multi-use forage-biomass candidates. Conversely, both native perennial grasses (switchgrass and eastern gamagrass) had high forage and biomass yields indicating their ability to serve as multifunctional filter strip-fodder-biomass crops. Therefore, to alleviate anthropogenic pressure on soil and water conservation in grassland systems, while allowing producers flexibility to respond to forage and biomass markets, switchgrass would serve as a superior multi-use filter strip species, with the perennialized species Kernza and silphium, as well as eastern gamagrass providing superior ecosystem services to that of the annual crop, wheat.

Technical Abstract: Vegetative characteristics such as perenniality drive hydrology and subsequent ecosystem services. However, this extent is unknown for newly released perennialized species, as is the potential for grazable filter strips to improve water quality, provide fodder, and optimize nutrient cycling in multifunctional systems. This study evaluated i) how species, perenniality, and community composition are linked to nutrient runoff; and ii) the multiuse forage-biomass potential of filter strips. Main effects were five species [eastern gamagrass (Tripsacum dactyloides), Kernza (Thinopyrum intermedium), silphium (Silphium integrifolium), switchgrass (Panicum virgatum), and winter wheat (Triticum aestivum)] either receiving broiler litter (5.6 Mg ha-1) or a control. Rainfall simulations were conducted at 5 cm hr-1 (until 30 min of continuous runoff) in summer and fall of 2019 and 2021. Kernza and silphium resulted in the lowest biomass regrowth, relative to native grasses, indicating perennialized species would not be ideal multifunctional forage-bioenergy crops. When evaluating the multivariate relationship between filter strip management and water quality, there was an association between soil and runoff variables, including soil electrical conductivity, NO3-N, water extractable phosphorus (P), and P saturation being positively correlated with runoff loads of total carbon and nitrogen (N), NH4-N, soluble reactive, total dissolved, and total P. Among all soil-plant-water variables, canonical correlation results suggest poultry litter applications (0.97) and soil P saturation (0.77) were the most influential variables for runoff water quality. Among all filter strips, switchgrass resulted in the highest runoff water quality and forage-biomass yields, thus improving water quality in multifunctional grazable filter strip systems.