Multivariate evaluation of soil-water-plant health in multifunctional buffer-strip systems

Buffer strips are vegetated edge-of-field areas primarily designed to filter sediments and nutrients, and protect water quality. Their ability to provide multiple ecosystem services derives from complex relationships between soil, plant, and environmental factors modified by management. Here, Partial Least Squares-Path Modelling (PLS-PM) was applied to identify driving factors of environmental quality and productivity in multifunctional buffer strips with a history of poultry litter (PL) applications (20+ years). Treatments were species eastern gamagrass (Tripsacum dactyloides (L.), intermediate wheatgrass (Thinopyrum intermedium (Host) Barkworth & D.R. Dewey 'Kernza', silphium (Silphium integrifolium Michx.), switchgrass (Panicum virgatum L.), and winter wheat (Triticum aestivum L.) receiving PL (5.6 Mg ha^-1) or unamended control. Using the Soil Management Assessment Framework (SMAF), we showed PL increased soil quality for Kernza (71%) relative to the control (67%), owing to greater organic matter accumulation and nutrient availability. The PLS-PM showcased buffer-strips' health (i.e., biomass production and nutrient uptake) was directly impacted by soil quality and nutrient runoff, with indirect effects from forage management. Increased ground cover was linked to enhanced biomass production and nutrient removal, with a positive impact on soil quality and overall system's health, despite reducing soil water. Nutrient runoff was inversely linked to soil quality and whole systems' health, underscoring the negative effects of nutrient and sediment losses to environmental quality. These findings illustrate the benefits of best nutrient management (e.g., optimizing PL application rates) and enhanced ground cover to improve soil and water quality, and forage production and nutritional value in multifunctional buffer-strip systems.