Companion Crops Boost Wheat Stubble Health

After harvest in the summer, many wheat farmers plant a double-crop cash crop. Others plant a cover crop. Some farmers do both.

For the last five years, Robin Griffeth and his son, Kelly, have used a strategy of companion cropping. They plant sunflowers mixed with cover crop species in order to glean a cash crop flow benefit, plus a cover crop soil health benefit.

“I like the idea of planting a cover crop in wheat stubble after harvest, but I didn’t want to give up a cash crop, too,” Robin says.

It’s worked. Soil health benefits have exploded. Meanwhile, the pair still gets bonus income from double-crop sunflowers.

Take a lesson from gardeners
Companion cropping is not a new concept; gardeners have used it for years. In commercial agriculture, however, it’s not always an easy concept to embrace. The Griffeths receive about 26 inches of rainfall each year on their farm near Jewell in north-central Kansas, so moisture is often the limiting factor in harvesting successful cash crops. Their crop rotation includes grain sorghum or corn, soybeans, and winter wheat. After wheat harvest, they spray the stubble with glyphosate to burn down any weeds prior to planting the companion crops.

The companion crop mix is diverse, including shallow- and medium-rooted grasses, brassicas, and broadleaves.

In 2014, they planted 42 pounds of total companion crop seed per acre. They aimed for about 24,000 sunflower plants per acre, with the companion crop mix (which included oats, cowpeas, sweet clover, and buckwheat) making up the rest. They use nontreated sunflower seed to reduce the impact on beneficial insects. Their cover crop seed dealer mixes the sunflower seed with the companion crop mix.

The Griffeths use a Great Plains box drill with 7.5-inch spacing, and they harvest the sunflowers with a Case header equipped with Lucke sunflower pans.

Past yields have ranged from 300 pounds to 2,000 pounds per acre. Kelly says sunflower yields with companion crops are less than sunflowers by themselves.

In 2013, for example, drought limited yield of the companion sunflower crop. Still, gross income offsets the cost of seed and planting. Plus, there are soil health benefits.

Dramatic improvements have been noted, although the effects may not be seen for a few years. For proof, Kelly points to this year’s grain sorghum crop following last year’s companion crop, on a typically poor-yielding farm.

“It is tough ground,” he explains. “Last year, I planted a multiple-species mix following wheat harvest on that farm. We had three brassica species (oats, buckwheat, and cowpeas) plus sunflowers. The sunflower yield was disappointing, and I considered it a failure.

“This year, the grain sorghum was incredible. The soil was alive with earthworm holes, and the soil was black because we kept it alive with the companion crops,” he says. “I don’t know if it will work everywhere, but it sure worked here.”

Head moths are often a problem in single-crop sunflowers. In the companion cropping system, they seldom need to be sprayed because beneficial insects swarm the fields, Robin says. He attributes these beneficial insects to the diversity that comes from a companion cropping system.

“At first, we wanted soil cover and nitrogen from the cover crops, but we’ve started seeing so many more benefits,” he says.

“Our priority is diversity, which I’m convinced gives so much more benefit than we ever thought,” he says.