Evaluating the soils in your vineyard requires, generally, several steps:
- Research the geologic parent material of your soils, which can be found in the Natural Conservation Service and Geologic Survey source: The Soil Survey. This will give you broad, baseline information about your soils and is a good place to start when assessing your site for farming potential.
NEW!! Toby O'Geen, UC CE Soil Resource Specialist, has updated the soil survey information online, so that it is easier to use and works with iphone, ipad or desktop. Choose "Soil Web" for the newest app. Then click on the menu button in the upper left corner to navigate. Check it out!
Toby's 2009 Grape Day presentation: "Understanding foothill vineyard soils: implications for nutrition and terroir" is available here as a PDF.
- Dig several soil pits on your property to assess soil depth and soil properties. A backhoe is best, but even a shovel will do. This is an excellent time to sample your soils and get them analyzed for basic properties:
- Soil texture
- Water holding capacity
- Cation exchange capacity
- Phosphorus, which is often low in foothill soils because it becomes tied up or "fixed". Since P is not highly soluble, you may want to add it pre-plant.
- Boron. Deficiency or toxicity.
- Organic matter content.
- Other parameters (nitrate-N, K, Zn, Mn, Cu, Fe,and Mo), if desired.
- IF desired, lime requirement (tons/acre) for soils with a pH of less than 6.5. Most foothill soils are indeed acidic (pH less than 6.5), and many growers do not add lime nor try to adjust the soil pH. Instead, they consider the acidic soil pH part of foothill "terroir".
Check our list of labs that do soils and tissue testing to determine where to send your sample.
A single vineyard site can vary greatly with respect to soil depths. These 2 soils pits, one shallow, and one so deep we couldn't reach bottom, were both dug in the same vineyard. What are the implications for vine management?