Managing weeds on an organic farm

Title: Managing weeds on an organic farm

[Rodale Institute 27 Oct 2012 By Patrick Lillard] -- Ken Rider grows organic corn, soybeans, spelt and wheat on almost 500 acres in the Great Black Swamp region of Ohio, USA. As part of an Organic Agriculture Research & Extension Initiative (OREI) project looking at organic farmers’ weed management, an undergraduate student from Purdue University and I interviewed Ken. When we asked him about how he manages weeds, he quickly replied cover crops, crop rotation and cultivation, but we learned those practices were best explained through stories and experiences. Ken’s observational skills have given him an understanding of the characteristics of his soil, weed life cycles, the attributes of different cover crops, and how all of these different elements interact on his farm. He then uses these observations to experiment, to develop and test new approaches that will hopefully improve his farming system. His observations and experimentation also provide him with the knowledge to be able to quickly adapt his system to respond to challenges. Comment

Cover crops

Rider’s favorite crop is alfalfa. He grew up among alfalfa fields, but, beyond the nostalgia, the crop has significant benefits on his farm:

Its deep-penetrating roots open up his heavy soils and access deep nutrient reserves.
It serves as a significant source of nitrogen for subsequent crops.
Its thick canopy suppresses weeds.
Its ability to be mowed provides a measure of control over challenging perennial weeds.

While alfalfa is his favorite cover crop, Ken is continually researching and experimenting with new cover crops and techniques. He currently has funding from NRCS’ Environmental Quality Incentives Program(EQIP) to evaluate the use of crimson clover and oilseed radish as a technique for reducing the amount of moldboard plowing he does. Ken’s thought is that as oilseed radish will winterkill and crimson clover is not as winter hardy as other clovers, spring incorporation will not require inverting the soil.

While cover crops do provide numerous benefits, they aren’t without their own management requirements. Ken once had an outbreak of Canada thistle in his alfalfa cover. He figures the thistle took hold because the field was in alfalfa for an extended amount of time and there were gaps in the stand. He addressed the outbreak by changing his rotation and mowing the thistle several times in a season, which put significant pressure on the thistle’s rhizomes and lessened the population.

Ken stresses that in organic agriculture, weeds are controlled but never eradicated. Therefore, organic farmers must be diligent managers. “My father-in-law used to say ‘mind your business,’” says Rider. “He didn’t mean ‘mind your own business,’ which is something everybody should do. He meant mind your business—be attentive.”

Observation is essential for successful cover crop and weed management. “Observation in a timely manner so you don’t get behind,” says Rider.

Crop rotations

Crop rotations are another integral component in Ken’s weed management system as they allow him to disrupt weed life cycles, minimizing any windows for weeds to flourish and reproduce. Ken’s rotation was outlined in Michigan State University’s publication Integrated Weed Management: Fine Tuning the System, but crop rotations are flexible structures, providing opportunities for controlling outbreaks.

Figure of Ken Rider's Crop Rotation on p. 19 in Integrated Weed Management:Fine Tuning the System from Michigan State University Extension

As described earlier, when Ken had an outbreak of Canada thistle in an alfalfa field, he changed his rotation, planting a crop with a thicker canopy that could outcompete the Canada thistle. He is using the same strategy to battle weed pressure created by this year’s drought. The lack of moisture after seeding slowed germination, which allowed the weeds to get established ahead of his crop. He is changing his rotation from beans-wheat to beans-corn, since the corn can better compete with weeds.

Cultivating conservatively

The last weed management strategy Ken reaches for is cultivation. While it is an effective tool, Ken is very conservative in his cultivation. He warns that the conventional mindset of wanting extremely clean fields can be detrimental for soil in general, but especially for clay soils.

“The biggest problem with [working the soil] as an organic farmer is the tendency to overwork it,” says Rider. “You want to go out there and get rid of all the weeds and make a real fine seedbed. When you do that, you’ve tightened your soil up. In our situation, that’s compacting it…You learn that when you get your next rain, it’s so sealed over and so tight that the water won’t drain through it.”

Ken minimizes this risk by limiting his cultivation and selecting implements that remove weeds with the least damage and compaction. There are several great resources on implements in their uses, one of the most well-known being Steel in the Field, which is available free online. It describes each implement, its effectiveness on different size weeds and provides case studies. One of the farmers profiled is Rex Spray, a pioneer of organic farming in Ohio and one of Ken’s mentors.

Observe and learn

Even after 40 years of farming, Ken is still perfecting his farming system, learning from experience and experiments as well as from other farmers and organizations. Ken’s mentor Rex Spray was an important source of knowledge over the years. Rex was an extremely well-known organic farmer who, in addition to appearing in Steel in the Field, was profiled in several articles over the years. Ken noted Rex had one of the most important skills for an organic farmer: observation.

Rex Spray (Photo by Danielle Deener)

“[Rex Spray] was very observant and knew what he was looking for,” says Rider. “If you’re perceptive and have a discerning mind, you can pick out a lot of things you need to know about your cropping just through observation.”

Ken noted another important source of information as the Ohio Ecological Food and Farming Association (OEFFA) and its grain-growers chapter. The chapter meetings and email listserv provide opportunities for farmers to discuss the topics most pertinent to them in the context of their own specific farms and share what has worked for them. Ken also acknowledged the benefits from collaborating with faculty at the Ohio State University on research trials and participating in organizations like the Sustainable Agriculture Research and Education (SARE) program. Ken served on North Central SARE’s advisory board and is a strong proponent for the organization, advocating for farmers’ continued involvement in SARE and utilization of its producer grants.

Original source

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Article: WeedsNews3994 (permalink)
Categories: :WeedsNews:research alert, :WeedsNews:organic farming, :WeedsNews:cover crop
Date: 8 November 2012; 12:56:22 pm Australian Eastern Daylight Time

Author Name: David Low
Author ID: adminDavid