Building Soil Health in our Vineyards

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Did you know the ground we stand on is alive? One teaspoon of soil is home to over a billion individual microbes from more than 10,000 species. The types of microorganisms include bacteria, fungi, beneficial nematodes, and many others. This vibrant community of organisms is crucial to the healthy functioning of the soil that provides water and nutrients to the vines.

what makes healthy soils:

  • A living matrix of plant residues, plant roots, animal residue and microorganisms.
  • Open spaces in a range of sizes to allow a balance between water and air in the soil and space for a complex network of microorganisms (bacteria, fungi, etc.), microarthropods and roots to establish.
  • A natural balance of substances to allow for nutrient cycling and conducive to the environmental needs of different types of soil organisms in the soil food web and vine roots.
  • Sufficient organic matter to provide nutrients for microbes.

What do these microbes do for the vines?

  • Efficiency and efficacy of nutrient cycling
  • Capacity to hold and release plant available water
  • Promote root growth

How do soil microbes do this?


Different soil microorganisms play different roles from preying on pathogenic microbes, breaking down dead material, converting compounds containing nitrogen and carbon into forms vines can utilize readily. Some soil microbes play an important role in nutrient cycling by breaking down organic matter, making it available as an energy and nutrient source for other organisms.

Some nutrients like potassium and phosphorus, which are often immobile in soil, are made available to the vine. Bacteria secrete sticky substances that hold the soil together and improve the capacity of the soil to hold water instead of letting it drain away making this water available to the vines later.

Our cover crop mix; a blend of oats, barley, peas and beans

Craig’s Fun Facts!

  1. A mature sheep eats 3-4% of their body weight (120-200 lbs.) every day and can produce up to 8 lbs. of manure per day!
  2. We plant multiple species of cover crops for different purposes. Barley and oats prevent erosion because they have very fibrous root systems. The also sequester carbon in the soil.
  3. Peas, beans, and clover convert nitrogen from the air into plant available forms as a natural fertilizer.
  4. Good quality compost is loaded with beneficial microbes to augment the microbial community in the soil.

How We Help our Soil Thrive

Building and maintaining the health of our soil is an ongoing process. Changes in soil are slow requiring constant encouragement of our microscopic friends. At Niner Wine Estates we use a range of methods to build and maintain the health of our soil, including:

1. Spread compost

The benefits of spreading compost under the vines are improved soil structure, inoculating the soil with beneficial microbes, and increasing the amount of water the soil can hold. We bring in some organic compost from a local producer, but we also produce a lot of our own with skins and stems from wine production plus material from the garden, kitchen, and landscaping.

2. Plant cover crops.

We plant two types of cover crops in alternating rows at 80 pounds per acre. Barley has a very fibrous root system that prevents soil erosion and increases the carbon in the soil to improve structure and water holding capacity. The type of barley we plant is Arivat barley which germinates at a high rate and in cooler winter temperatures. The other type of cover crop we plant is a mix of beans, peas, crimson clover, and oats. The oats provide many of the same benefits as barley. The beans, peas, and clover capture nitrogen from the air and turn it into natural fertilizer and food for soil microbes. They are also flowering plants that attract pollinators.

3. Graze sheep and goats

If there is enough rain and the cover crops  grow big enough to provide adequate forage value we graze sheep and goats. Grazing eliminates the need for a mowing pass in the spring. When sheep digest the plants they eat the nutrients in those crops are more available to the plants and beneficial microbes. Any breed of sheep or goats will get the job done. A shepherd brings their flock to us. This is called contract grazing. The shepherd gets free forage for their flock and we get the soil benefits. A true win-win situation.

ABOUT THE AUTHOR

Craig Macmillan is our Critical Resource Manager. He tracks our sustainability efforts, leads staff and public education and is the mastermind behind our private tour program. He holds three degrees: a B.S. in Philosophy, an M.S. in Plant Protection Science and a Ph.D. in Sociology. His extensive education is paired with thirty years of hands-on experience, including growing grapes, making wine, teaching, conducting research and podcasting. With this blog series we’re helping you learn from (truly) the best!