Viticulture - Regenerative Viticulture and Soil Health Session

Lauren Picone | Corinne Butler | Cristina Lazcano | Charlotte Decock*

On-Farm Assessment of Long-Term Effects of Regenerative Management on Vineyard Soil Health

Lauren Picone, Corinne Butler, Cristina Lazcano and Charlotte Decock*

*Grimm Family Center for Organic Production and Research, California Polytechnic State University, San Luis Obispo, CA, 1 Grand Avenue, San Luis Obispo, CA, 93407, cdecock@calpoly.edu

This study assessed the effects of long-term, stacked regenerative management practices on soil health across 87 vineyard blocks in California with diverse management histories, microclimates, and soil types. Soil health indicators including aggregate stability, mineralizable carbon, and soil organic carbon were analyzed to develop region-specific rating curves. Soil health indicator average values trended lower than established framework values, emphasizing the need for commodity- and region-specific rating systems. Long-term cover cropping (≥10 yr), particularly when combined with other practices, significantly improved soil health scores. The integration of livestock emerged as a practice capable of accelerating soil health improvements, yielding benefits in less than 10 yr. Findings highlight the importance of tailoring practice combinations to specific soil types and climactic conditions to achieve soil health goals. These results contribute to the growing body of evidence supporting the need for comprehensive, yet adaptable, soil health rating systems.

Funding Support: Foundation of Food and Agriculture Research California Department of Food and Agriculture Specialty Crops Block Grant

Effects of Stacking Regenerative Management Practices on Soil Health, Vine Quality, and Yield in a Sonoma, California Vineyard

Paige Davis,* Axel Herrera, Connie Wong, Amanda Rodriguez, Kerri Steenwerth and Cristina Lazcano

*UC Davis, 1 Shields Ave, Davis, CA, 95616, pedavis@ucdavis.edu

Regenerative management practices in vineyards are gaining traction as we shift to building self-regulating systems that need fewer synthetic inputs and disturbances to soil and vines. While regenerative practices have been studied individually, this study looks at the effects of stacking these practices in a vineyard in Sonoma, California. The 17-yr-old vineyard is planted with Cabernet Sauvignon on a 101-14 rootstock with a Positas Gravelly Loam soil type. The regenerative practices included a reference with conventional management (RF) and combinations of compost (C), no-till (N), and grazing (G): C, N, GC, NC, and GNC, with three replicates for each treatment. Treatments were applied for two growing seasons from 2022 to 2024. We hypothesized that stacking of practices would increase soil and vine health. Vine row and tractor row soil samples were collected in 2024 at two depths (0 to 15 cm and 15 to 30 cm). Soils were analyzed for bulk density, aggregate stability, gravimetric water content, EC, pH, water holding capacity, total carbon and nitrogen content, microbial respiration, permanganate oxidizable carbon, microbial biomass carbon, potentially mineralizable nitrogen, ammonium and nitrate levels, and phosphorus. Leaf samples were collected at veraison and analyzed for macronutrient (N, P, and K) and micronutrient (Zn, Fe, B, and Cu) content. Grape yield was recorded and grape quality was analyzed for juice and berry phenolics and a range of basic chemistry properties (glucose, fructose, total soluble solids, etc.). We will use analysis of variance to compare soil health indicators across treatments, providing evidence of how regenerative management affects different aspects of vineyard soil function. A correlation analysis will evaluate the relationships between soil health indicators and leaf nutrients to better understand the effects of regenerative agriculture. Integrating soil, vine, and yield analyses will provide insight into potential benefits or tradeoffs of regenerative management, such as changes in grape quality.

Funding Support: Foundation for Food and Agriculture Research California Department of Food and Agriculture

Noelymar Gonzalez-Maldonado* | Kerri Steenwerth | Mallika Nocco | Erika Yao | Luisa Robles

Ideal Vineyard Soils from Grower Perspectives Ddiverge from Traditional Soil Health Paradigms

Noelymar Gonzalez-Maldonado,* Kerri Steenwerth, Mallika Nocco, Erika Yao and Luisa Robles

*USDA-ARS and UC Davis, 1110 Plant & Environmental Sciences Building, LAWR Department, One Shields Ave, Davis, CA, 95616-8627, ngonzalezmaldonado@ucdavis.edu

Soil health is essential for sustainable winegrape production. However, soil health metrics and guides designed from annual cropping systems may not correspond to needs and goals for winegrape production. The traditional soil health paradigm promotes organic matter accumulation and turnover to enhance nutrient cycling and maximize crop yield, while vineyard management focuses on balancing vine vigor and optimizing grape quality. This study aimed to identify soil health indicators associated with growers’ desired vineyard outcomes, while accounting for soil properties, management, and sampling variability. Soil samples were collected from 16 grower-identified ideal and 16 challenging vineyard soils. Soils were rated based on their ability to regulate vine vigor and produce high grape quality in Napa Valley. Samples from vine rows and tractor rows (0 to 20 cm depth) were analyzed for total carbon (TC), permanganate oxidizable carbon (POXC), mineralizable C (Min C), microbial biomass C (MBC), dissolved organic C, total N, plant-available N (NO₃^–-N, NH₄⁺-N), potentially mineralizable N (PMN), pH, EC, bulk density, wet aggregate stability (WAS), penetration resistance, and infiltration rate. Soil texture was a key factor influencing soil health indicators and growers’ differentiation between ideal and challenging soils. Ideal soils had slightly lower levels of clay and silt content and lower TC, POXC, TN, EC, and WAS indicators. Higher soil health levels were observed in tractor rows with vegetative cover compared to bare vine rows, suggesting that soil samples should be taken from both zones. No-till practices enhanced TC, Min C, and NH₄⁺-N. Enhancing these properties could support soil structure and resilience to extreme weather conditions. These findings emphasize the value of integrating growers’ perspectives into defining soil health with respect to distinctive winegrape production goals, highlighting the need to adapt traditional soil health frameworks to better serve perennial vineyard systems.

Funding Support: American Vineyard Foundation Western SARE USDA ARS

10:00 am – 10:20 am	On-farm Assessment of Long-term Impacts of Regenerative Management on Vineyard Soil Health Lauren Picone, California Polytechnic State University, San Luis
10:20 am – 10:40 am	Effects of Stacking Regenerative Management Practices on Soil Health, Vine Quality, and Yield in a Sonoma, California Vineyard Paige Davis, University of California, Davis
10:40 am – 11:00 am	Ideal Vineyard Soils from Grower Perspectives Diverge from Traditional Soil Health Paradigms Noelymar Gonzalez-Maldonado, USDA-ARS, California

Viticulture – Regenerative Viticulture and Soil Health Session

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