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Cover crops spur slacker soils

One spring, Stud Swenson supplemented wrestling calves during calving season with nightly 5-mile runs.

After calving, he worked in morning weight training that coincided with tossing seed corn bags during planting.

Later that summer, he started swimming laps in his farm’s pond in conjunction with daily scouting walks as he traveled between his fields on his bicycle.  

At harvest, Stud lived up to his name by squeezing in a triathlon between combining runs.

After harvest, though, Stud went soft. Couch time watching ESPN nixed weight-lifting crunch time. Stud swapped countryside runs for double-cheeseburger sprints. And he subbed morning swims with morning showers. Not surprisingly, six-pack soon described his beverage of choice instead of his abs.

Switch To Soils

OK, Stud Swenson is a fictional farmer. His fate, though, mirrors what’s occurring in many soils.

During the growing season, soils hums with activity of soil microorganisms that benefit crops. For example, mycorrhizae fungi create filaments on the edge of a crop plant’s roots that extend its water and nutrient uptake. Meanwhile, crop roots readily suck up nutrients and water throughout the growing season.

After harvest, though, many soils enter slacker status as plant growth exists.

The friendly microorganisms that benefit your soil starve. No crop cover leads to soil erosion. Compaction spurred by field operations remains. Water unused by the crop can hamper next spring’s planting. Unused nitrogen can escape into groundwater or tile lines.

Enter Cover Crops

They can make your soil mimic an Olympic sprinter year-round. Cover crops can extend the feeding frenzy that soil microorganisms enjoy during the growing season.

“We have to have something growing most of the year, compared to something just five to six months out of the year,” says Nick Bowers, a farmer and co-owner of KB Seed Solutions, a Harrisburg, Oregon, cover crop firm.

Cover crops also curtail erosion and break up compaction. Constant cover encourages earthworms to thrive. Earthworms create soil tunnels that aid rainfall infiltration. This nixes runoff and helps ensure that moisture migrates to crop roots. Cover crops may benefit water management.

“Farmers in eastern South Dakota and Minnesota could benefit just as much from cover crops as drain tile,” says Dwayne Beck, manager of the Dakota Lakes Research Farm near Pierre, South Dakota.

Cover crops can salvage excess nitrogen (N) and convert it into organic N not prone to leaching or denitrification. That not only benefits farmers but it also spares communities downstream from high drinking water nitrate levels and hypoxia that starves marine life of oxygen in water.  

Cover crops, when combined with no-till and diverse crop rotations, are a way to deep-cycle plant nutrients like nitrogen, says Beck. “We are losing nutrients 4 to 5 feet deep that aren’t coming back,” he says.

So What Could Go Wrong?

Plenty. “Cover crops add a whole new level of management to farming,” says Bowers. “You have to understand what kind of cover crop to have, how to handle it, and make sure your planter is set up to plant through it.”

Killing a cover crop is crucial for the success of the incoming primary crop. “We learned a tough lesson that first year,” says Jack Maloney, a Brownsburg, Indiana, farmer. “You need to know the best time to apply glyphosate. You can’t apply it in cold, cloudy weather.”

The cover crop annual ryegrass best uptakes herbicide under warm temperatures.

“The mistake we made the first time was when we started spraying glyphosate from dawn to dusk,” he says. “In the morning, we got little kill. By 11 a.m., we killed 100% of annual ryegrass. Later in the afternoon, we killed hardly anything, and after sunset, we got no kill.

Left to survive, wounded weeds heal quickly. “The trouble with seeds escaping glyphosate is that they can escape it again and eventually become resistant,” says Maloney.

Cover Crops Key Solutions

Managed properly, though, cover crops can benefit soils and also provide big-picture perks. Agricultural runoff has been implicated in degrading water quality of the Gulf of Mexico and the Chesapeake Bay. Cover crops help retain and recycle nutrients that would otherwise run off into rivers, lakes, and oceans.

“I really think that whoever has been out in Chesapeake Bay looking at daily load limits has their sights on the Upper Mississippi Basin,” says Howard Buffet, who chairs the Howard G. Buffett Foundation and operates a 1,500-acre farm in central Illinois.

“There are a lot of evidence-based arguments (for increased regulations) that can be made that are not in the farmer’s favor. Cover crops can be a huge contributor toward solving some of the problems we have.”

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