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Organic Crop Producer Study Circle Focuses on Weed Management

Posted: September 1, 2011

Twenty organic grain farmers met at Summit Valley Farm in New Holland, PA in July. Part of Penn State Extension's new Organic Crop Producer Study Circle series, the focus was on organic weed management for corn, soybeans, spelt and hay.
Wade Esbenshade explains his strategy for weed management for soybeans.

Wade Esbenshade explains his strategy for weed management for soybeans.

Wade Esbenshade farms 135 acres of corn, soy, spelt and alfalfa with his father. When he moved back to the farm in 2003 they made the move to organic production and have been certified organic since 2007 on the home farm and 85 neighboring rented acres. Their primary markets are local organic dairies. Spelt is sold food grade to a local mill.

"This was a pretty good year for weed control," Wade told us. The weather cooperated and he was able to cultivate on time. You could tell, weeds were scarce and small under the canopy.

At Summit Valley, Wade uses the basic tools of good weed management: rotation, cover crops, blind cultivation, and field cultivation. The details, like timing and equipment adjustment contribute to his success.

Rotation

The basis of Summit Valley's weed control strategy is good rotation. "The longer you can be in a perennial crop the better," Wade told us. Wade's rotation is hay (3yrs) > corn > soy > spelt > clover >corn> soy > spelt > hay.

Soil preparation

The corn field we were looking at had clover which was plowed in, disked, then field cultivated and planted. Wade just started using a European style plow. Overum makes this plow which has longer mold-boards that do not fully flip the soil. This makes it pull easier and allows shallower plowing to keep organic material close to the surface where the microbes can break it down quickly. Meeting participants were worried it would not burry weed seed and leave a uneven field surface. Wade still is experimenting with this plow, but so far says "it definitely pulls easier and I find it leaves a nice even surface."

Timing is key

"I like to till and plant the same day so the crop has the advantage on the weeds," Wade commented. Timing your planting date right is also essential. Wade finds that later plantings generally have better weed con-trol. He plants 107 to 112 day corn which planted the 20th to 25th of May usually dries down fine. Timing can be tricky. Wade likes beans to come out of the ground in 3-4 days – which means waiting for good soil temperature and moisture. He also looks for a window where it will be dry enough to cultivate 3 or 4 days after planting. "If it is going to rain all week after I planned to plant, I wait," he told us.

cultivated corn
Blue River corn tine weeded one time and cultivated twice.

Blind Cultivation

Four to five days after planting Wade cultivates with a Kovar flex tine harrow to blind weed. Thin wires stir just the top ¼ to ½ inch killing tiny weeds before they have emerged. The crop is not up yet and corn planted 1 ½ inch deep is not bothered by the sur-face disturbance. The trick with tine weeding is it works best on tiny weeds before they emerge. If you can see the weeds it may already be too late. Three great things about a flex tine weeder are it kills in-row weeds, it‟s fast (Wade runs it at 8-10 mph) and it helps conserve moisture and suppress new weeds by creating a dust mulch in the top ¼ inch. This thin dried layer holds moisture below and makes it hard for the weeds to germinate. Wade recommends not trying to use any down pressure. In fact, he recommends using a wish bone attachment to help each set of tines float independently. He finds the equipment rides more evenly, with fewer jumps and skips using this attachment.

Cultivation

Generally two cultivations are enough. Next year Wade plans to try a belly mounted cultivator that might help with precision. However, his fields are reasonably flat and their pull-behind field cultivator works well.

Future refinements

Weed management at Summit Valley is good, but Wade is always looking to improve. This year he might try a summer fallow with a few passes of shallow tillage after spelt harvest. He hopes that this shallow cultivation will help reduce the weed seed bank. Then he will plant clover to build soil organic matter. He is also interested in rolling cover crop rye and no-till planting soybeans to reduce time on the cultivator and improve soil organic matter. After talking with farmers that have seen consistent success, he is willing to try it.