This article originally ran in the fall 2017 issue of New Farm Magazine, the magazine of Organic Farmers Association. All OFA members receive a complimentary issue of New Farm twice per year. Click here to sign up!
Organic farmers share strategies that reduce weeds without herbicides while protecting the soil’s health.
by Christopher Bond
Organic farmers invest so much in their most valuable resource, healthy soil, yet they often undermine their investment by tilling it too frequently. “We spend a great deal of time, energy, and resources working to improve the health of our soils,” says Jeff Moyer, executive director of Rodale Institute and author of the definitive book Organic No-Till Farming. “Much of that work is destroyed by tillage,” which breaks down soil’s structure and disrupts its ecosystem of beneficial organisms. Many conventional field-crop growers have reduced or eliminated tilling, but they typically plant genetically modified varieties that have been created to survive the application of herbicides used to kill weeds. Organic no-till systems put cover crops, such as rye and vetch, to work suppressing weeds while also building better soil. No-till farmers often roll over the crops to create a dense mat that prevents weeds from sprouting, but each farm adapts the basic principles of the process to its own conditions, crops, and resources. Here’s how three different certified-organic growers are using no-till techniques in their operations.
MULCH ON MULCH
“We use a variety of techniques to prepare our planting beds, and they change with the seasons and the crops,” says Dan Pratt, manager of Astarte Farm in Hadley, Massachusetts. “Bolstering soil microbiology so that root, or mycorrhizal, fungi can thrive is our primary focus. We are currently in the process of creating various cropping systems that do not require any (or require only minimal) tillage and rely exclusively on compost and bio- char blends for fertility.”
In 2014, Pratt began trying no-till methods in the garlic field of the 6-acre vegetable farm, and he is continuing to work out a strategy for all of the crops. He uses multiple layers of mulch to suppress weeds. For up to three months before planting, he covers the soil with strips of black woven polyester (ground cloth) that are held in place with ground staples or weights. “We prefer to use them on top of rolled-and-crimped cover crops, but we will also use them immediately after a crop harvest, particularly if there was high weed pressure in that bed,” he explains.
At planting time, Pratt applies an inch or two of compost and plants directly into the bed or rolls out WeedGuardPlus paper mulch. “The paper is OMRI listed, and it comes in a variety of choices with prepunched planting holes or in solid rolls,” he says. “In 2017, we tried laying out round bales of straw and planting through that mulch.” To turn cover crops into a layer of mulch on top of the soil, Pratt attaches a roller-crimper to his tractor. The tool was made by Pennsylvania’s I & J Manufacturing based on a design developed at Rodale Institute.
Organic no-till methods require patience by farmers, Pratt warns. “It takes several seasons [without tillage] to begin building up sufficient mycorrhizal activity in your soils, and several more to reap the benefits of increased soil aggregation and biological activity.”
In 1995, Jay Armour of Four Winds Farm in Gardiner, New York, stopped tilling his vegetable rows and formed permanent beds using a back blade mounted on a tractor. Instead of planting cover crops, he spreads a thick layer of compost on the beds each year. The first year after he stopped tilling, he noticed a remarkable decrease in weed pressure and started to see the soil’s organic matter rise quickly.
“Today, with our soil organic matter at between 8 and 10 percent, we understand the other benefits of not tilling: better absorption of water during heavy downpours, better retention of water during dry periods, and maintaining a soil environment rich in microbial life,” Armour says. “Plus we can produce crops closer together because we don’t need to get cultivating equipment in, so we grow a lot of food in a small space.”
Armour makes the compost using a forced-air system that he designed several years ago. “I mix manure from our cows with horse manure trucked in from a nearby farm, lay it out on pipes, blow air through the pipes, and wait for the pile to heat up,” he explains. “Since I came up with this design, I now have more compost than I need and am actually starting to sell it. The key to our approach is lots of compost. Unscreened compost is better because it stays longer in the field.”
Small grains, legumes, and other types of “green manure” outcompete weeds, increase organic matter, stimulate microbial action, and provide stability and structure to the soil while helping to prevent erosion. For farmers using no-till methods, these cover crops can also serve as weed-suppressing mulch.
Winter annuals work well for no-till farming because they grow when the cash crop is out of season. Legumes increase fertility by fixing nitrogen in the soil. Cover crops that have a high carbon-to-nitrogen ratio break down slowly, allowing them to work as mulch for the whole season. And those that produce a bounty of biomass—roots, shoots, and leaves—build soil structure and its organic matter content. Here are a few options to consider.
Source: Organic No-Till Farming, by Jeff Moyer (available at acresusa.com, amazon.com, and other booksellers)
Like many farmers transitioning into organic production, Tom Ryan of Ryan’s Rose Organic Farm in Batavia, New York, had to embark on some preparation of the land. His parcel had been under a conservation easement—that meant there were no agricultural chemical residues in the soil, but there had been uncontrolled vegetative growth for the previous 10 years. He used his tractor’s disc to break up the hard roots, and then he planted rye and field pea crops. With help from Cornell University researchers, the retired biophysicist determined that this combination was best because rye contains compounds that inhibit weed growth, while field pea adds nitrogen to the soil.
In spring, Ryan knocks down the cover crop with an I & J Manufacturing roller-crimper. In his experience, it is often necessary to roll the crop twice to ensure it is killed com- pletely and forms a thick mat. He then plants soybeans through the layer of dead cover crops.
Ryan has been sharing his experience with organic no-till methods and advising neighboring farms that grow such diverse crops as cut flowers and grains. Despite the initial expenses in equipment, he believes that reducing or eliminating tillage pays dividends like less time spent in the field, lower fuel costs, better weed control, and no pesticide residue in the soil.
Christopher Bond is the manager of the McKay Farm and Research Station at Unity College in Maine. He has previously written for Acres U.S.A., Maximum Yield, and other agriculture publications.