Grapes - Soils & Cover Crops

Soils in the Vineyard

Soil is an amazing hidden ecosystem beneath our feet. While the average person may think of soil as just static dirt, it is amazingly complex and teeming with life. A single teaspoon of productive soil contains between 100 million and 1 billion bacteria. Maintaining healthy soil is key not only to the longevity of any farming operation, but

to our continued ability to feed ourselves.

“Man — despite his artistic pretensions, his sophistication, and his many accomplishments — owes his existence to a six inch layer of topsoil and the fact that it rains.” – Paul Harvey

Soil is a complex mixture of things that you can’t change, and things that you can. Soil depth, texture and mineral composition are largely unaffected by land use practices. You can however influence water infiltration rates, amount of organic matter in the soil, structure, compaction and more through management decisions. Modern farming often relies on tilling and chemical fertilizers, however these can be damaging to the long-term health of your soils.

The Importance of Soil

Best Management Practices Promoting Soil Health

Minimize Bare Soil

Bare soil dries out quickly, can erode with rain, develop a hard crust that prevents water from penetrating, and even blow away in the wind. Reducing the amount of bare soil in your orchard can go a long way to improving your soil health. Soil can be covered with an organic mulch, a cover crop, or even plant residue (cut weeds, prunings and thinned leaves etc.)

Add Organic Matter

Organic matter is a portion of your soil that consists mainly of dead, decomposing or decomposed plant matter. Organic matter has many benefits in soils including increasing water infiltration and water holding capacity, improving soil aeration, improving the ability of the soil to hold on to nutrients, and enhancing the diversity of disease-suppressing soil microbes and invertebrates Organic matter can be added to the soil by growing cover crops, top dressing with compost, mulching cuttings & clippings on site, or even adding an organic mulch.

Cover Crops

Cover crops can help build organic matter in soils, fix atmospheric nitrogen, increase water infiltration rate, and even act as a fumigant to reduce populations of harmful nematodes. Different cover crops are needed for different desired outcomes. Cover crops may provide habitat for vertebrate pests like voles, mice and moles so use caution in sites with rodent problems or ensure frequent mowing to reduce habitat desirability. If you have drip irrigation, some other form of overhead or under canopy irrigation will likely be required to grow cover crops in our hot, dry climate.

Increase Soil Biodiversity

Increasing the diversity in microbes in your soil will help to cycle nutrients, break down organic matter, provide better plant growth and nutrition, and may even help to suppress pests, and disease. Soil biodiversity can be increased by increasing above-ground diversity. Growing different cover crops or a mixture of plants in your cover crops in your drive rows can increase soil biodiversity. Adding livestock can also increase nutrient cycling and soil biodiversity. Matching the type of livestock and grazing timing is important or they may damage trees or eat fruit.

Limit Tillage

Tilling can be necessary when breaking new ground or when soils are compacted. Tilling can also be and effective method to control certain weeds, however frequent repeated tilling can lead to increased erosion, decreases in nutrients and organic matter, below-ground compaction, and reduced microbes and beneficial invertebrates.

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Soils in the Vineyard