Reduced soil disturbance as a regenerative agriculture practice in organic winter squash production : short-term trade-offs in yield, soil health, and greenhouse gas emissions

A growing body of evidence shows that, over the long term, organic and regenerative agricultural practices, including reduced soil disturbance and cover cropping, can improve soil health, crop productivity, biodiversity, and climate change mitigation while lowering fuel and input use. Given these benefits, reduced-disturbance practices have been adopted widely in certain cropping systems but less so in organic vegetable systems, which rely on intensive tillage for weed control. Thus, despite reported long-term benefits, the short-term trade-offs remain unclear, impeding adoption in organic vegetable production. This study evaluated the short-term effects of three regenerative practices on organic winter squash relative to the current standard: Summer Cover Crop (SCC), No-Tillage + Tarp (NTT), Reduced Tillage + Tarp (RTT), and Standard Tillage (ST). Treatments were compared for crop yield, soil health indicators, and greenhouse gas emissions at the UBC Farm in Vancouver, British Columbia, over two field seasons (2024–2025). Across most indicators, NTT, RTT, and SCC did not differ significantly from ST. Yield showed no significant treatment effects, and no differences were observed in any of the soil health indicators measured, including nitrogen availability, aggregate stability, and earthworm abundance. Carbon dioxide (CO₂) and nitrous oxide (N₂O) fluxes were closely tied to the timing of physical disturbance events, but no significant treatment effects were detected on any individual sampling date. Cumulative CO₂ emissions and yield-scaled CO₂ emissions, however, were significantly higher in NTT than ST during the 2025 production season, reflecting a short-term trade-off consistent with the literature. Across treatments, CO₂ and N₂O emissions were substantially higher than values reported for comparable reduced-tillage vegetable systems, likely reflecting UBC Farm's baseline soil conditions. Although NTT showed elevated CO₂ emissions in the 2025 production season, findings across most indicators suggest that, over the short term, reduced-disturbance practices did not incur trade-offs that would prevent adoption, a necessary first step toward realizing their long-term benefits reported in the literature. Adoption decisions may be guided by practical factors like labour and site-specific goals, while longer-term, regionally grounded research is needed to establish these practices’ full agronomic and climate implications in the Pacific Northwest.