Cover crops a long-term solution?

Soil loss affects the long-term sustainability of human life on Earth.

Nutrient loss affects the immediate and long-term environment.

In a corn-bean rotation, cover crops might address both issues.

Most people in agriculture agree that cover crops are integral to the sustainability of food production around the world. However, some are concerned they may rob too much from the main cash crop.

To deal with the overall question of cover crops, researchers recently received a $4.7 million grant from the global food security arm of the U.S. government.

Some of this money goes to North Dakota State University to examine how corn-bean farmers can maintain sustainability while reducing their negative impact on the environment, says Marisol Berti, the scientist in charge of the NDSU component of the project.

“Our main problem is soil erosion,” she said. “We never have time to establish a cover crop after we harvest corn or beans.”

The corn harvest is often delayed until freeze-up, leaving no time to seed.

As well, virtually no residue is available to protect the soil following the soybean harvest.

As a result, Berti said it’s a major problem for both crops.

The cover crop concept also works well in a wheat-bean rotation used by some farmers, she added.

“The answer is to inter-seed a cover crop while the main crop is still growing,” she said.

“We’re trying different crops, different dates and as many different combinations we can think of to find the best way to use cover crops.

“Farmers know they need cover crops, but they have no method to put them into the rows. So they try aerial seeding. You can’t use big-seeded crops like peas or fababeans because they need to be planted deep. They mainly use rye, sometimes a little turnip and radish seed. No matter what you seed from the air, it needs rain right away. If you don’t get rain, seeds (sit) on the surface and don’t germinate.”

Aerial seeding in North Dakota costs only US $15 acre, but lightweight seeds are often blown away in the wind.

North Dakota farmers used aircraft to seed 10,000 acres of cover crop into corn and bean fields this year. However, Berti thinks the ultimate answer lies with Gene Breker’s new cover crop drill.

“We use Gene’s drill for inter-cropping into soybeans, also,” he said. “It’s not just for corn. We’re interseeding two or three rows between the soybean rows on 30 inches and corn on 30 inches.

“It’s more difficult in the soybeans because it’s a low crop. The canopy closes up so there’s no line for the planter openers. We don’t know the best timing. We don’t want the cover crop to grow up too much because then at harvest you have all this extra green stuff into the combine. Lots of questions.

“In beans, we’re looking for cover crops that grow very low to the ground and can tolerate shade under the canopy. We’re trying winter peas, but so far they don’t survive North Dakota winters. We’d like them to work because they fix nitrogen and your next crop is corn. We’re trying radishes, peas, rye and camolina, which you know in Canada. The camolina looks pretty good.”

Her group is also investigating the possibility of double cropping, which is turning the cover crop into a secondary cash crop.

Camolina with beans has the best prospects, but it doesn’t have a stable price. It might be financially viable once the camolina market has been developed.

Berti said the project had a major hurdle to clear right from the start because the researchers couldn’t find a machine to meet their criteria for seeding between corn rows.

There was no point in pursuing the research based on aerial seeding, and the experimental cover crop seeder designed at Pennsylvania State did not have the versatility they wanted.

“We looked at the Haigie, which is just a high clearance sprayer they modified to seed cover crops,” she said.

“I was at a field day to see this one. It looked really good, but it’s like aerial seeding. You’re not incorporating the seed, and I think that’s necessary.

“So Gene created this multi-purpose drill for us. It can plant two or three rows intercropping, or it can side-dress at the same time with liquid or granular. And we can do strip till when we need to. He’s a very smart man.”

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