Runoff nutrient export and peanut yield under partial biogas slurry substitution with vetiver hedgerows on red soil slopes

Partial replacement of chemical fertilizer with biogas slurry can recycle nutrients, but its production benefit must be considered alongside runoff export. We compared chemical fertilizer alone (CF100), 50% substitution of chemical-fertilizer nitrogen with slurry (CF50BS50), and the same mixed-fertilizer regime with vetiver (CF50BS50VG) in the same nine 40-m 2 plots on a 5° red-soil slope in Jiangxi, China, in 2022 and 2023. Nitrogen inputs were intended to be equal, whereas phosphorus and potassium were not balanced. Relative to CF50BS50, recorded runoff under CF50BS50VG was 58.3% lower in 2022 and 45.4% lower in 2023 (Holm-adjusted P = 0.016 and 0.053). Higher phosphorus concentrations in the vetiver treatment in 2022 coincided with lower mean runoff exports than under CF100, illustrating the distinction between concentration and load. In 2023, its recorded total nitrogen and phosphorus exports were 114.63 and 9.75 g ha -1 , compared with 346.38 and 24.74 g ha -1 under CF50BS50; however, none of the primary nutrient-export contrasts met the 0.05 threshold after multiplicity adjustment. Adding vetiver was associated with 12.9% lower grain yield in 2022 and 24.7% higher yield in 2023 (adjusted P = 0.084 and 0.036). The runoff pattern thus contrasted with a reversal in the yield contrast. These findings concern monitored surface-runoff water and the tested mixed-fertilizer regime; they do not establish a slurry-by-vetiver interaction or complete erosion-related nutrient retention.