What is a healthy soil for winegrape production? Grower perspectives differ from soil health paradigms

Authors: GONZALEZ-MALDONADO, NOELYMAR - University Of California, Davis; Steenwerth, Kerri; NOCCO, MALLIKA - University Of Wisconsin; YAO, ERIKA - University Of California, Davis; ROBLES ZARAGOZA, LUISA - Pennsylvania State University; MOONILALL, NALL - University Of California, Davis; LAZCANO, CRISTINA - University Of California, Davis

Submitted to: European Journal of Soil Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/15/2025
Publication Date: 1/4/2026
Citation: Gonzalez-Maldonado, N., Steenwerth, K.L., Nocco, M.A., Yao, E.H., Robles Zaragoza, L., Moonilall, N.I., Lazcano, C. 2026. What is a healthy soil for winegrape production? Grower perspectives differ from soil health paradigms. European Journal of Soil Science. 2026; 77:e70265. https://doi.org/10.1111/ejss.70265.
DOI: https://doi.org/10.1111/ejss.70265

Interpretive Summary: Soil health is important to agricultural sustainability, yet few studies link soil health assessments to specific outcomes needed by growers. This study integrates grower participation to align soil health indicators with outcomes of interest in winegrape production. We evaluated the variability of common soil health indicators in 32 vineyards with respect to grower ratings (16 ideal vs. 16 challenging soils), soil texture, vineyard zones, and management practices (till vs. no-till) in Napa Valley, California, USA. Soils were rated by growers based on their perceived influence on vine vigor control and grape quality and we measured a set of biological, physical, and chemical soil health indicators. Our findings suggest that total carbon (TC), permanganate oxidizable C (POXC), total nitrogen (TN), ammonium, and wet aggregate stability are relevant indicators of soil health for winegrape production in California's North Coast. However, grower perspectives were strongly guided by soil texture due to its strong association with soil water management and vigor control. Thus, higher values of TC, POXC, TN, ammonium, and wet aggregate stability were associated with poorer agronomic outcomes in finer soils, which contradicts the current soil health paradigm. Most soil health indicators were enhanced under the plant-covered and non-irrigated tractor rows compared to bare and irrigated vine rows. Soil TC, mineralizable C, and ammonium were higher under no-tillage. These results highlight the value of integrating growers’ views into soil health research and the need for crop-specific soil health research and outreach. Grower participation facilitated the identification of indicators linked to management decisions. Moreover, the study underscores the importance of soil sampling, texture and management as guides for interpreting soil health for winegrape production.

Technical Abstract: Soil health (SH) is linked to sustainable agriculture, yet few studies link SH assessments to specific crop-relevant outcomes needed. This study integrates grower participation to align SH indicators with relevant outcomes for winegrape production. We evaluated the variability of common SH indicators with respect to grower ratings of soils (ideal vs. challenging), soil texture, vineyard zones (vine vs. tractor rows), and tillage management (till vs. no-till). Soils were collected from 16 challenging and 16 ideal vineyard soils, rated by growers based on their perceived influence on vine vigor control and grape quality in Napa Valley (California, USA). Surface soil samples were collected at two depths (0–10, 10–20 cm). The indicators evaluated included total carbon (TC), perman-ganate oxidizable C (POXC), mineralizable C (Min C), microbial biomass C (MBC), dissolved organic C (DOC), total nitrogen (TN), NO-3 -N, NH+4 -N, potentially mineralizable N (PMN), electrical conductivity (EC), pH, bulk density, wet aggregate stability (WAS), penetration resistance, and infiltration rate. Our findings suggest that TC, POXC, DOC, TN, EC, pH, and WAS are relevant indicators of SH for wine grape production from growers' perspectives. However, grower perspectives were guided by soil texture due to its strong association with soil water availability and vigor control. Finer texture soils with higher TC, POXC, TN, and WAS were associated with poorer agronomic outcomes, contradicting current SH paradigms. Most indicators were higher in the 0–10 cm depth and in the plant-covered tractor rows compared to the 10–20 cm depth and the bare, irrigated vine rows. Bulk density was higher under tillage, especially at 10–20 cm, while POXC and Min C were higher in the 0–10 cm under no-till. These results high-light the value of integrating growers' views into SH assessments and the need for crop-specific SH research and outreach. Grower participation facilitated the identification of surface SH indicators linked to their current management decisions. This study under-scores the importance of texture and management as guides for interpreting surface SH indicators and provides insights on further considerations needed to make SH assessments more relevant for winegrape production.