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Early Cover Crops in Corn

Planting a cover crop early while adding fertilizer works for these North Dakota brothers.

For Mitch and Andy Hoenhause and their father, Harvey, farming is like a recipe that they keep adjusting to make better and better. This year, they believe they have cooked up a plan to seed a good cover crop and to sidedress knee-high corn at the same time.

The equipment will be newer and higher tech than some they’ve used in the past, but it will include a few modifications – something the brothers are well known for around Lisbon, North Dakota. Mitch and Andy admit they tend to stray from traditional methods and experiment with their own ideas. 

Some work; some don’t. Planting a cover crop early and adding fertilizer at the same time, though, is a method that seems like a keeper. 

Cover Crop Conundrum

The Hoenhauses switched to no-till on their 5,000 acres in 2001 and started adding cover crops in 2008. Initially, the cover crops helped absorb excess surface water and created a firm living root surface so they could farm wet ground. The more they used cover crops, the more they realized other benefits like adding nutrients and building soil health. While it was relatively easy planting cover crops after harvesting early crops such as wheat and field peas, planting cover crops after corn was a challenge. 

They tried several methods, including renting a RoGator with a spinner box to plant in tall corn and aerial-seeding, which was expensive and often ineffective. They knew earlier was better.

“Ideally, the cover crop has the best chance of germinating and growing when the corn is no higher than knee-high,” Mitch says. There’s less canopy so more sunlight reaches the plants, and there is usually more moisture. 

The brothers knew what they wanted and decided to build their own interseeder. 

Prototype 1

Their first planter was a modified corn cultivator toolbar. They removed the shanks and mounted old John Deere 71 plate planter units for the disk opener and a Valmar box for small seed. 

“Our idea was that the planter boxes would put in large seed, but the boxes were old and didn’t work. So we stuck with small seed (cover crops),” Mitch explains.

The openers worked like a drill, planting the seeds more than 1 inch deep. The good soil contact and early planting (mid-June to early July) gave plants a healthy start.

“You want to get it in early to get it out of the ground, then when the corn turns yellow, it takes off,” Andy says. They also noticed that plants in the north/south end rows grew better than plants in the east/west rows. 

After corn harvest, the cover crop really took off and provided excellent grazing for cattle.

Moving up with Hagie 

While the homebuilt equipment worked, the brothers recognized an opportunity to improve their fertilizer system when they saw a Hagie NTB (nitrogen toolbar) 16-row sidedressing tool. Instead of applying all their fertilizer when they plant, they believe a split application will use less fertilizer and be more effective. 

Also, with a Hoenhause modification of the toolbar, the Hagie handles two jobs at once: applying fertilizer and planting a cover crop.

For spring planting in 2015, they mounted the Valmar seeder to the toolbar. Unfortunately, the parts they needed to incorporate the seed into the soil didn’t arrive before it was time to plant.

“Broadcasting is always hit and miss,” Mitch says. Still, it was all they could do at the time. 

The seed they broadcast for neighbors (while doing custom work planting and sidedressing) was a hit and received timely rains. The cover crops grew well and provided good cattle grazing in the fall. Then the Hoenhauses got a miss. Without timely rains after planting seed in their corn acres, their cover crop didn’t amount to much. 

“This year, we added Lilliston spider gangs to the Hagie sprayer to stir the ground like a rotary hoe to get the small seed covered,” Andy says. “Since we are 100% no-till, we can’t use drag teeth. This rotates, and we can adjust it to make it more or less aggressive.”

The Recipe

Time will tell if the latest Hoenhause modification works as well as anticipated. Here are some things the brothers know for certain about planting cover crops in corn.

Plan ahead on herbicides choices. This will ensure that herbicide carryover doesn’t adversely affect your cover crop choices. That’s not always easy when there are serious weed issues. So when possible, stick to chemicals that don’t carry over long term.

Cover crops don’t reduce corn yields. The Hoenhauses plant 27,000 to 29,000 seeds per acre and average 150 bushels of corn per acre on fields with and without cover crops.

Just 5 to 6 pounds per acre of a radish/turnip seed mix works well for their soils. Their grazing cattle seem to like the combination, too. Other crops like peas can be planted, but they keep the seeding light (10 to 20 pounds per acre) and plant after the corn has gotten a good start. Experiment with cover crops that work best for you. 

The brothers plant cover crops in about one half of their corn acres each year. Part of it is because of weather and timing. Three people only have so much time to get all the spring work done. The other factor is weeds. The Hoenhauses choose fields that are fairly weed-free to plant cover crops in. 

If possible, don’t broadcast seed. Drill or incorporate it somehow. The brothers have had enough failures to know how important that is. 


They’ve had enough successes, too, that neighbors have noticed and now hire Mitch and Andy to plant cover crops for them. Their innovations have also caught the attention of Abbey Wick, North Dakota State University Extension soil health specialist. 

“Interseeding cover crops into corn is a home run for the Hoenhauses,” she says. “It is a great way for them to get cover for longer to control weeds and erosion and to provide a food source for the soil microbial community to keep them active for longer. Also, it’s great for grazing.”

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