Companion Crops After Wheat Stifle Weeds

The fallow period between winter wheat harvest in summer and planting season the following spring is rife with opportunity to add either a double-crop cash crop or a cover crop. But why not both? 

A growing legion of farmers is seeing advantages of cash and cover crops grown at the same time, a practice called companion cropping. It’s a practice that can add between $30 and $60 of revenue to each acre, says Chad Basinger, who farms near Pretty Prairie, Kansas. 

For the past three years, Basinger has added a cocktail of cover crop species to double-crop grain sorghum, all planted in combination after wheat harvest in June. The combination of cover crop and sorghum seed was essentially the same as a cover crop cocktail by itself. 

“With harvested grain sorghum, this gave me a chance to get a commercial crop off,” he says.

In 2018, the Kansas farmer added 11 pounds total of a cover crop cocktail, including cowpeas, mung beans, buckwheat, radishes, flax, dwarf essex rape, and turnip cover crop seeds to the grain sorghum, which was planted at a rate of 4 pounds per acre. All of this was planted into standing wheat stubble right after harvest. 

He used both compartments of his John Deere air seeder to place the seed; grain sorghum in one tank and the cover crop cocktail in the other.

The grain sorghum yield on one of his companion crop fields averaged 42 bushels per acre; on another, 30 bushels per acre. Basinger reckons the break-even cost for the cover crop and grain sorghum mix, plus planting and harvest, is about $60 per acre – or 18 bushels per acre, if grain sorghum cash price is $3.25 per acre. 

Bonus Benefits

Adding yet another wrinkle to the equation is that Basinger finds the companion crop system offers several weeks of grazing for his cowherd. 

Basinger runs cows on the sorghum stalks from November to February or March – whenever the cows begin to calve. He says the cows love grazing the diverse mix. 

“The cows were content, even in February, eating on this mix, compared with conventional sorghum stalks where they came from and weren’t as content,” he says. “We put them on the companion crop mix to graze, and it didn’t look like there was much out there to eat, but they were content.”

Mature cows will do a good job of picking at the turnips and radishes, Basinger adds. Stocker animals tend to be a little pickier and less patient at getting those brassicas.

Adding grazing to the system boosts soil health benefits, notes Darrin Unruh, agronomist at Kauffman Seeds, a seed supplier near Haven, Kansas. 

“Chad’s done a great job of figuring out how the tools work in the whole farm system,” Unruh says.

Though Basinger sees additional opportunity with the companion cropping system, there are more components to manage. 

Often, the fallow period after wheat harvest lends itself to weeds, which usually require multiple herbicide or tillage passes. Planting the companion crops right after wheat harvest can suppress those flushes of volunteer wheat and other weeds.

In 2018, however, central Kansas had torrential rains, giving weeds a big boost.

“I sprayed one field with dicamba when the sorghum was a foot tall. I got rid of the weeds and was surprised that the cowpeas and mung beans survived,” he says. 

In another field, crabgrass took over. He sprayed the edge of that field with glyphosate and paraquat, but the middle of the field had crabgrass pressure that dinged sorghum yields. 

The lesson: A field with grassy weed history may not be an ideal fit for a grain sorghum companion crop.

Basinger cautions that some of the companion crops can compete with sorghum at harvest. Mung bean and cowpea seeds are similar enough in size to grain sorghum that they could blend in with the cash crop in the combine. 

In 2016 and 2017, the sorghum heads were tall enough that he was able to nip off the sorghum heads. In 2018, the covers and cash crops were about the same height, so there was some comingling but no dockage at the elevator.

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