Organic annual vegetable farming systems often rely on intensive tillage for weed management due to the prohibition of synthetic herbicides. Regenerative organic agriculture aims to improve soil health and reduce the frequency and intensity of soil tillage by using cover crops as high-residue mulches to suppress weeds. In southern coastal California, the moderate climate supports year-round vegetable production, discouraging many growers from integrating cover crops into their operation and leaving sustainability-minded growers with few strategies to produce organic vegetables outside of reliance on tillage. This study evaluates standard organic tillage practices versus high-residue cover-crop mulch system on squash, peppers, and eggplant over two seasons. We assessed treatment effects on soil health indicators, weed pressure, and crop production. Soil under the cover-crop system improved soil organic matter, organic carbon and nitrogen, microbially active carbon, and water infiltration compared to bare soil. Weed biomass was substantially lower under the high-residue mulch due to persistent surface cover. Crop yield was 82%, 169%, and 189% higher in the cover-crop plots for squash, pepper, and eggplant, respectively. These findings demonstrate that high-residue cover-crop systems can enhance soil health, reduce weed pressure, and substantially increase yields, providing evidence-based strategies for implementing regenerative organic practices in vegetable systems.

Plastic mulch is widely used in organic strawberry production but raises sustainability concerns due to its persistence, disposal challenges, and contribution to microplastic pollution. This study evaluated the potential of high-residue cover crops and living mulches as alternatives to plastic mulch in coastal California. Over two seasons (2022–2024), we compared five mulching treatments: black polyethylene mulch (Plastic); a white clover (Trifolium repens) living mulch (Clover); two roller-crimped sorghum–sudangrass and field pea mixtures (Sorghum 1, Sorghum 2); and a roller-crimped buckwheat–pea mixture (Buckwheat). The objectives were to evaluate the effectiveness of these treatments on (i) soil properties and biological indicators, (ii) weed suppression, and (iii) strawberry yield in organic systems. A schematic timeline was developed to depict cover-crop growth, termination, and strawberry production across both years. Compost (10 t·ha⁻¹) and fish emulsion (5–1–1 NPK, 4 L·ha⁻¹ biweekly) were applied to all treatments during fruiting. Sorghum residues produced the highest biomass (up to 23 t·ha⁻¹) and supported yields comparable to plastic mulch in 2023. Under lower-yield conditions in 2024, sorghum-based treatments outperformed plastic. Soil responses were modest and time-point specific: Sorghum 1 showed higher organic C and organic N pre-harvest in 2023, and both sorghum treatments increased soil organic matter pre-harvest in 2024. Biological indicators such as CO₂–C and microbially active carbon declined seasonally across all treatments, indicating strong temporal control. Weed outcomes diverged by system—Clover suppressed weeds effectively but reduced yield by >50% due to competition, while Buckwheat decomposed rapidly and provided limited late-season suppression. These results demonstrate that rolled high-residue cover crops, particularly sorghum-based systems, can reduce dependence on plastic mulch while maintaining yields and enhancing soil cover. Living mulches and short-lived covers may complement residue systems when managed to minimize competition and extend ground cover.

Climate change–driven increases in drought and rainfall variability present new challenges for grape production, even in regions with historically high precipitation. Rootstock selection and irrigation management are important tools for optimizing vine performance and fruit and wine composition, yet their combined effects remain poorly understood in hybrid grape cultivars grown in humid regions. We evaluated own-rooted Chambourcin and vines grafted to 1103 Paulsen (1103P), 3309 Couderc (3309C), and SO4 under three irrigation regimes (none, 50% ET replacement, and full irrigation) over three growing seasons in Missouri, USA. Across 105 trait-by-year combinations, including vine physiology, yield components, berry chemistry, and berry and wine volatiles, we partitioned variance explained by irrigation, rootstock, their interaction, and vineyard block. Irrigation exerted year-dependent effects on vine water status, gas exchange, organic acids, and selected volatiles, with the strongest physiological responses in 2014, when precipitation was lowest and water-balance deficit was greatest. However, irrigation effects were not limited to this dry year, as selected berry chemistry, vine growth, and wine volatile traits also differed among irrigation treatments in years with less pronounced water stress. Rootstock consistently influenced vine size and vine balance, with 1103P and 3309C increasing pruning weight and generally lowering Ravaz indices, while yield responses were more vintage dependent. Berry volatile composition was only modestly affected, whereas wine volatile profiles were more strongly shaped by rootstock, particularly for norisoprenoids, esters, and terpenes. Grafted-versus-own-rooted contrasts identified 24 affected variables, but these responses reflect grafting to the evaluated rootstocks rather than graft-union effects alone. Overall, irrigation and rootstock exerted partially distinct but complementary influences, highlighting the importance of integrated water and rootstock management for optimizing hybrid grapevine performance and wine style in humid environments.