You might look at the lush ground covering in our orchards and see weeds. But we see cover crops. “Cover crops” are plants that cover the ground so we don’t have bare dirt. Bare dirt brings two problems: dust erosion and water erosion. Basically, when the ground is uncovered, the sun and air take carbon out of the soil and up into the atmosphere. When you cover the ground with something alive and growing, you’re sequestering carbon in the soil and preventing erosion. Topsoil is the layer in soil where you’ll find the most nutrients, minerals, and organic matter needed to grow food. It’s the first layer to go when the ground is uncovered or when farms till. And it takes about 500 years for nature to make one inch of topsoil.* It takes just minutes to lose that much with tilling.
One of the biggest parts of regenerative farming (as opposed to conventional) is a focus on dirt and carbon. When you hear the word “carbon” it’s probably most often in the context of our warming planet. That’s carbon dioxide, which in too high quantities in the atmosphere creates a lot of problems. But carbon itself isn’t “bad.” It’s the building block of all living things. Plants need it to make nutrients and to grow. The more carbon that soil can absorb and hold onto, the more nutrients it can give to the plants and the more water it can hold during a drought.* Carbon sustains life.
In addition to sequestering carbon in the soil, cover crops also provide habitat for native pollinators and beneficial insects, who then help protect and fortify the orchards, counteracting the insects that pose threats. The list of benefits goes on and on.
There are literally hundreds, if not thousands, of plant species that are used as cover crops. Choosing the right mix of cover crops is a whole science unto itself, and requires careful management on the part of the farmer and their crews. Not all “weeds” harmonize with the trees. And we measure the nutrients in the soil periodically to make sure they’re doing their job. Farm Assistant Rachel Sullivan collects samples of the soil every year in consistent locations around the farm and sends them to a lab to be tested. She returns to the same spots to test both the surface soil and the deeper soil. That way, she can compare the data from previous years and help Farmer Al make decisions for the next.
Walking around the orchard, you’ll see that the understory is covered in either local grasses or plant mixes of legumes, barley, and oats. The legumes “fix” nitrogen into the soil, meaning they take nitrogen from the atmosphere and convert it into nitrogen that can be used by microbes and plants. The grains have roots that reach really deep, which creates better soil structure and increases the soil's water holding capacity. These deep roots (called “taproots”) also feed the microbes that live in the soil AND bring up nutrients from deeper soils into the plant. Sour clover (Melilotus indicus) is another “nitrogen-fixing” cover crop we grow on the farm. It helps ward off gophers, who are repelled by the coumarin in its roots. That in turn keeps the orchard healthy, since gophers chew and kill a lot of our trees every year.
So why isn’t every farm doing this? Most farms don’t want what they call “weeds” competing with their target crop, which is what they plan to sell. Weeds do compete a little for water and nutrients in the soil, but what we do at the farm is we manage the weeds so we’re still getting the benefit of the cover crop covering the soil, but we’re not losing out to them. We’re also fortunate to grow perennial crops (trees, rather than an annual crop like tomatoes), which are well established in the soil. The cover crops don’t gain control of the soil environment to the detriment of our crop.
They’re a lot of work to maintain, though. When the grass gets tall, our ground team cruises through with weed whackers. Weed whacking creates a thick layer of mulch (or dead organic matter on top of the soil), that keeps the soil cool, keeps moisture in, keeps it from eroding, and it provides habitat for critters. Once we mow those grasses, those minerals will decompose and fertilize the top levels of the soil. This is nature’s beautiful circle of nurturing itself with a little help from us.
We try to leave our soil better than we found it. We take great care to nurture its microbial life. It’s all about trying to cooperate with nature, rather than control it. It’s like being out in a park here. There’s a vitality above and below the soil. And that ultimately makes the fruit sweeter. It’s better for the environment and it’s better for those of us that eat the food.