Courtesy iStockphoto/Thinkstock Turning young weeds into the soil before they can mature and go to seed helps reduce the number of future weeds. |
Every farm has weeds, and the last thing a busy hobby farmer needs to do is waste time. Managing weeds on a farm is a different ballgame than a nursery, but many of the weed-management tactics described below are effective across the board, no matter what type of property you’ve got. They’re intended to be simple, cost-effective solutions to your worst weed woes, freeing up your time, money and energy for other, more fun farm chores.
What is a Weed?
Before we tackle weed-management techniques, we first need to define what makes a particular plant a weed. It’s also important to understand why some weeds are worse (or better) than others. Tom Lanini, an extension weed ecologist at the University of California at Davis, says a weed is classically defined as a plant out of place.
“But to expand on that,” he adds, “I think a weed is a plant that causes economic or aesthetic loss.”
Economic loss could be in the form of reduced yield or the cost of managing the weed, and aesthetic loss is how the weed’s presence impacts the overall visual appeal of your hobby farm. This is in the eye of the beholder, says Lanini. Every hobby farmer has his own level of tolerance for weeds in regard to the aesthetics of the farm, meaning that some people will find it necessary to control weeds more than others. Let your own tolerance be your guide, bringing weeds in check when you feel they are impacting your bottom line to an undesirable point.
Using Lanini’s definition, when looking at a ditch alongside your driveway that’s filled with grasses, field daisies, goldenrod and other plants, do you see a weed or a patch of wildflowers?
“Weeds provide a wide range of benefits or ‘ecosystem services,’” says Eric Gallandt, a weed ecologist with the University of Maine. In a situation like this, he says, “they protect the soil from erosion, cycle nutrients, [and] offer habitat and food for many organisms,” including thousands of species of predatory beneficial insects and pollinators. There are no crops growing in that ditch, so there’s little to no economic loss, and the aesthetic issue could be a loss or a gain depending on your opinion of field daisies and goldenrod.
“Weeds can be good in some situations,” Lanini adds, even in your fields. “During the time that a crop is not being grown, they may act as a cover to help cycle nutrients, preventing them from being leached. Low-growing, shallow-rooted weeds in an orchard or vineyard are obviously not impacting yield and could help provide a firm surface during rainy periods.”
The point is to choose your weed battles carefully.
Proactive Weed Management
Design
In many situations, the design and layout of your hobby farm’s planting beds can determine how many weeds you’ll have. Diverse gardens that contain a multitude of plant species are less likely to face weed woes. Monocultures, especially those with a lot of exposed bare ground between plants or crop rows, are welcome mats for weeds.
Planting gardens and fields with a variety of crops, each filling their own layer of the garden’s canopy and thereby completing the garden like pieces of a jigsaw puzzle, leaves less room for weeds and reduces nature’s tendency to fill the gaps with its own “weedy” biodiversity. Be as diverse as you can in your plantings, and choose easy-to-maintain native species whenever possible.
Mulching
Anything applied to the soil surface with the intent of reducing weeds, cutting down on watering and stabilizing soil temperatures is considered mulch. Agronomist Preston Sullivan suggests using organic mulches, such as pine straw or cover-crop residue, to help control weeds. Applying 3 or 4 inches of these products, straw, shredded leaves, untreated grass clippings or compost around plants (but not directly on them) and between rows keeps weed seeds in the dark and prevents them from germinating.
Covering the soil with unwaxed corrugated cardboard or several sheets of newspaper before laying down the organic mulch takes weed prevention a step further and serves as season-long weed control. Plastic-film mulches are effective, too, though they’ll be headed to the landfill after a season or two of use.
Biodegradable film and paper mulches are a terrific addition to the weed-fighting arsenal and are able to control weeds just as effectively as plastic films without the need for disposal. At season’s end, they can be tilled into the soil. The films are made of a cornstarch-based material, and the paper versions are derived from recycled paper coated in a vegetable resin.
Cover cropping
Fallow ground is prime real estate for weeds. Shield bare soil and out-of-rotation fields with a cover crop. Annual cover crops out-compete weeds and recycle nutrients back into the soil while holding it in place and preventing erosion. Low-growing perennial cover crops, like clover and alfalfa, become a living mulch if planted between rows during the growing season. They also serve as a nectar source for beneficial insects while luring pollinators and displacing weeds.
Lee Reich, PhD, a garden and orchard consultant and author of Weedless Gardening (Workman Publishing Company, 2001), notes, “Some cover crops, such as rye, oats and sorghum-sudangrass hybrids have an alleopathic effect; that is, they combat weeds by releasing natural weed-suppressing chemicals into the soil.” In his book, he mentions a study in which rye effectively reduced pigweed by 95 percent, ragweed by 43 percent and purslane by 100 percent. “The effect,” he says, “is only on small seeds,” making it possible to plant large seeds, such as corn, cucumbers and squash, directly in the field after the rye has been cut.
Irrigation
When irrigating the garden with overhead sprinklers, water is lost to runoff and evaporation, and more often than not, paths and margins are irrigated right along with the desired plants, causing weed seeds to germinate and weed seedlings to thrive. Installing a ground-level or below-ground drip-irrigation system targets water precisely to plant’s roots, eliminating waste and discouraging weeds.
Managing the seed bank
The aim of this proactive measure is preempting weed-seed production in the hope of reducing the future weed population. Gallandt describes this approach as farmers mechanically or manually cultivating “early and intensively enough to give the crop a competitive size advantage and then letting the crop take care of itself. Yield will not suffer from later-emerging weeds, but many of these will mature and can produce considerable seed rain, thereby replenishing the weed population for next year,” he says. “An alternative to this management philosophy is to manage the weed-seed bank. This will require cultivation and hand weeding early in the season, as before, but with an additional focus on [the removal of seed heads] or growing short-season crops that mature before weeds go to seed. The aim is to preempt weed-seed production. Without seed rain, weed densities will be lower in subsequent crops, and weed management requires fewer cultivation passes and less hand weeding.”
Go no-till
A 1986 study reported in the journal Weed Science noted that by simply not tilling a tobacco field, farmers saw a 68-percent reduction of weedy grass species and 71-percent reduction of broad-leaf weeds. Tilling brings weed seeds buried beneath the soil to the surface, where they are exposed to light and can germinate. No-till methods do not disturb the soil through cultivation.
Conventional no-till farming often involves the application of chemical herbicides to kill existing weeds; seeds are then planted through the weed residues. Organic farmers and gardeners can either use organic herbicides in the same manner or top-dress planting beds with regular additions of organic matter, causing a layered, mulching effect and encouraging the resident soil life to thrive undisturbed. Both Gallandt and Sullivan remind us, though, that no-till methods tend to shift weed troubles away from annual weeds and toward perennials, which, unfortunately, may be more difficult to control in particular areas.
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