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Planting Into Green Cover Crops
Folks driving by fields that Doug Toussaint and his sons, Nick and Brad, plant to soybeans likely do a double take.
That’s because the Wahpeton, North Dakota, farmers plant soybeans into a standing cereal rye cover crop. No tillage trips, no preplant herbicide passes, nothing.
“We just go in with no special attachments on our planter and plant,” says Nick Toussaint. “It looks amazing. The soils are so mellow that it’s like planting into a garden.”
The Toussaints contrast this with planting soybeans into cereal rye killed 10 to 14 days before planting. “If this (cereal rye) was already dead, we would be planting into a wet, dead mess,” says Doug Toussaint.
It doesn’t appear to negatively impact soybean yields as it enhances soil health, weed control, and lowers input costs, says Abbey Wick, North Dakota State University Extension soil health specialist. “I’m not as worried about increasing yields as not hurting them,” she says.
Cover crop benefits
More and more farmers in areas of southeastern North Dakota and west-central Minnesota are planting green.
“One of the great things about having a cover crop like cereal rye growing in the spring is that it helps manage moisture, which is especially important under no-till,” says Wick. The practice works particularly well on high-clay soils that are slow to dry. Cereal rye can lap up rainfall prior to planting, whereas a field devoid of a cover crop can stay sopping wet.
Planting green isn’t risk-free. Drought can rob soil moisture needed by the incoming cash crop. On sandy soils, an oat cover crop works better than the cereal rye/planting green strategy, says Wick.
On heavy soils, though, lies an excellent seedbed. Unlike tillage, planting green creates no root-balls and root masses that pose planting roadblocks, says Doug Toussaint.
He says moisture meter measurements taken at planting reveal no differences between soils with standing cereal rye vs. tilled soils. The cereal rye also curbs wind and water erosion.
“When we cut through the trash, we make a nice little slice,” he says. “We have nothing fancy on our planter. It’s a standard unit – no trash whippers or anything that can get caught on residue. We plant soybeans 1½ to 1¾ inches deep, right where we want.
“Planting cereal rye is our tillage pass,” he adds. By doing so, they’ve saved $30 per acre on tractor depreciation, diesel fuel, and equipment maintenance, he says.
Undisturbed no-till fields with a living root system also expand earthworm populations. The soil tunnels they carve help channel precipitation into the soil instead of leaving via runoff.
Undisturbed soils help support a thriving microbe community that helps crops better absorb nutrients. Meanwhile, inputs are minimal. Doug Toussaint recalls one field they planted to cereal rye in August 2014 with the intent of harvesting it as a cash grain the following summer.
“The only pass we made was aerially adding 100 pounds of nitrogen,” he says.
After harvesting the rye in the summer of 2015, they left volunteer plants over winter and planted soybeans into the field in mid-May 2016. Other than a glyphosate application following planting, soybean seed, and the planting pass costs, they made no investment in the field.
“With three seasons of rye roots, we established some drainage this land has never had,” says Doug Toussaint.
Soybean Seedbed and Cover Crop
In other fields, they will plant cereal rye in late September or early October (after small grain harvest) and plant soybeans into it the next spring. They fit a cover crop into every part of their crop rotation that includes small grains, corn, soybeans, and sunflowers.
Going green also slices weed competition. In 2015, NDSU soil scientists measured field weed pressure without and with cereal rye that’s planted green in a field. They measured six cereal rye and six noncereal rye strips for biomass.
Weed numbers tallied the same in both strips. However, weed biomass was nearly 10 times in strips where cereal rye was not planted vs. cereal rye plantings.
A living green carpet seems like it may be a haven for disease. The good news is, Iowa State University (ISU) trials have found there is no significant disease difference between soybeans planted with or without a cover crop.
Crop Insurance conundrum
One big drawback exists. Some farmers face hurdles in qualifying for crop insurance.
On the plus side, farmers in most of the central and eastern Corn Belt states can do it. The Risk Management Agency has ruled they may terminate a cover crop at or within five days after planting but before crop emergence to qualify for crop insurance.
In states west of there, though, it’s not so simple. Farmers in central and western Minnesota may terminate their cover crops at or before planting to qualify for crop insurance. Meanwhile, farmers in states like North Dakota and most of South Dakota, Nebraska, and Kansas must terminate their cover crops 15 days or earlier before planting.
There’s an out for farmers planting green, though. Farmers who obtain a written opinion from a local expert like an Extension or NRCS official who endorses green planting can qualify for crop insurance, says Gary Luebke, a soil health and crop insurance consultant from Rosemount, Minnesota. They should give proof of research data or experience citing the merits of the practice.
“I’d expect a soil or crop specialist, as well as a local certified crop adviser, to be able to give good reasons to alter the termination date,” says Luebke. “Just make sure this person puts it in writing to give to the farmer’s crop insurance agent.”
These days, lots of products touted to boost soil health are hitting the market. Still, farmers are better off putting money into proven products like cereal rye, says Wick.
“Rather than spending $6 to $7 per acre on unproven products, that money could be invested in cereal rye that protects the soil and enables farmers to plant green the next year,” she says. “That is the better investment.”
Soil Structure and Cover Crop
By Gil Gullickson