The MacLeod field trial is located in Kenwood, California within the Sonoma Valley American Viticultural Area (AVA).
Tillage is one of the most common vineyard practices in California, varying in frequency and area. While tilling is largely considered beneficial, supporting soil moisture and controlling weeds, the practice also comes with possible tradeoffs in soil health, labor and costs, and erosion risk. In order to better inform farmer decision-making and investment in Sonoma, this demonstration project investigates the impacts of tillage practices in vineyards on overall soil health and soil moisture.
Tillage: Three common vineyard tillage systems (all-row till, alternate year tillage, no-till).
MacLeod Family Vineyards tended to 30 acres of vineyards used to produce zinfandel, merlot, and sauvignon blanc grape varieties. MacLeod Family Vineyard was the realization of a more than 50-year-old family dream. They strove to grow top quality premium grapes that would make award-winning wines and learn and work together as a family, all the wine creating a resource and opportunity for future generations. Their goal was to grow quality grapes that displayed strong varietal character and expressed the unique terroir of the Sonoma Valley vineyard. As of 2020, the property has changed hands.
Prior to the field trial establishment, a cereal-legume cover crop mix – OSB Plowdown – was planted in tilled rows each fall. The greater vineyard was managed with alternate tractor row tillage, with rows alternating every 4-6 years.
Map Unit | Slope | Soil Texture | Organic Matter (%) | AWHC (cm/cm) | Depth to Root Restrictive Layer (cm) |
Laniger Loam | 15-30% | Loam | 3.0 | 0.16 | 74 cm |
Grape Varietals: Zinfandel
Irrigation system: Drip
The field trial was initiated in 2016 and continued until 2019. Monitoring concluded in 2019.
The trial was conducted on approximately 1,414 linear feet across 9 vineyard rows (~1 acre). A zinfandel block was chosen for the trial because of its relatively uniform slope and soil. The trial included 9 total plots, each 100 feet long. A plot included the vine row and adjacent tractor rows on each side. The 9 plots included 3 repetitions of each tillage management system: no till, alternate tilled rows, and full till.
In fall 2017, the tillage treatments were implemented in the tractor rows using a standard wheel disc. A cereal-legume cover crop (OSB plowdown) was planted at 50 lbs per acre rate each fall, and resident vegetation was allowed to grow in untilled areas. Each plot was managed in its designated tillage regime for the duration of the trial through October 2019, with standard mowing in winter and spring, and tillage in spring and fall. Alternate tilled rows were flipped each spring.
Variable(s) | Sampling Method | Sampling Equipment Used | Timing/Frequency | Analysis Method | Sampler |
Soil texture, organic carbon content, soil organic matter, active carbon, bulk density | Composite samples (3-4) taken in the middle of tractor rows at 0-10cm and 10-20cm. | Spring 2017, Fall 2019 | |||
Soil moisture | Probe in center of vine row to track relative moisture levels at 8” intervals down to 30-48” depth. | Aquachek Probe, data logger | Measurements recorded every 30 mins year-round | Aquachek web software |
Keith Abeles
Sonoma RCD
Anya Starovoytov
Sonoma RCD
The Gamble Ranch Field Trial, located in the Oakville AVA in the middle of Napa Valley, incorporates the Mainardi plow with compost application and green manure cover cropping, and monitors the effects on soil properties and vineyard productivity.
Napa County RCD’s Huichica Creek Vineyard trial sought to demonstrate conservation practices including those to promote soil health, carbon sequestration, erosion control, water conservation, and irrigation scheduling.
This Sonoma County Vineyard trial seeks to investigate the economic and soil health tradeoffs of compost application in combination with common tillage practices.
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