Viticulture – Breeding & Cultivar Evaluation Session

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

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

Noelymar Gonzalez-Maldonado,* Kerri Steenwerth, Mallika Nocco, Erika Yao, Cristina Lazcano
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