Adding cover crop forages into row crop rotations is an obvious way to expand feed availability when supplies are tight, but there are challenges associated with interspersing the two.

Now in year three of a four-year multi-state grant project, researchers at Colorado State University are looking into how substituting annual covers in place of fallow in dryland cropping systems affects soil moisture, soil health and overall profitability on the High Plains.

Farmers had a chance to hear research updates and see sample fields planted to fall cover crops in northwest Kansas at a recent workshop hosted by the K-State Extension Service.

In recent years, the benefits of having more forage options have been obvious.

“There isn’t a pasture in northwest Kansas that couldn’t use a little additional rest,” said Sandy Johnson, K-State’s area livestock specialist. “But how do you work that into your system? That’s the big challenge.”

According to her cost estimates, it requires around $70 a head to graze cattle on covers. Research out of Nebraska showed a wide range in per acre expense — from as low as $26 to as high as $76 — netting on average 66 days of grazing with a rate of gain of just under 2 pounds per day.

“The cost of gain was competitive with anything else we might do with those calves,” she concluded.

Forage covers can also be used to improve cow or heifer condition prior to breeding. “You can’t do it with a straight corn diet, but you can do it with a high quality forage mix,” she said.

Forages can produce a double-crop behind wheat on less water than it takes to fill grain, added Jeanne Falk Jones, K-State’s area agronomist. However, there is potential for yield drag down the line.

“We need to really think about what that next crop is going to be,” she said. “It’s great to take advantage of that late summer moisture when we have it, but in the drier years it will have an adverse effect on the following grain crop.”

She also pointed out that many popular wheat herbicides have long residuals, which can impact the viability of cover crop plantings. “Lots of broad-leaf species are susceptible. We could be spending a lot of money to get a diverse mix out there, when herbicide carryover is still a factor (suppressing that),” she cautioned.

Triticale is one popular cover crop component resistant to long-lasting wheat herbicides, but it has a drawback: it can harbor the wheat curl mite, the transmission agent for wheat streak mosaic. The mite can travel on the wind, meaning it has the potential to harm neighboring fields.

“Once we have it, there’s nothing we can do for it,” Jones said.

On the flip side, many farmers in the area were dealing with hailed out wheat and wondered if planting covers early enough would help suppress volunteer wheat, which serves as the wheat curl mite’s prime host.

Late season moisture can bring out multiple flushes of regrowth in wheat stubble. The longer the volunteer remains in the field the greater the risk of disease transmission.

“Getting a full in-season cover crop established is important to do before the volunteer comes in,” agreed local farmer Matt Wilson, a CSU research cooperator.

Wilson farms north of Bird City, Kan., and has two fields in the CSU study. He’s been grazing pairs since mid-July on one field that adjoins native pasture with an existing water source and plans to run replacement heifers on the second following the first freeze.

Waiting to graze until after a freeze eliminates the risk of toxicity from high nitrates or prussic acid.

Wilson said forage covers have allowed him to expand the number of cows he can run on the same land. He is currently up to 170 cow-calf pairs.

“It’s really worked well for me the last couple of years,” he said.

This fall, his farm is one-third corn, one-third milo and one-third forage covers. In his experience, following covers with milo resulted in too much volunteer millet, so now he plans to follow them with corn to try to get better weed control.

Farmers are often cautious about planting rye, a notorious source of contamination in wheat. But neighboring farmer, Josh Sowers, who joined Wilson on a producer panel, said he had found rye indispensible in a good late season forage mix.

When he left it out to save on seed costs, he was disappointed. “We had to bring protein back out for the cows,” he said. “I learned my lesson and got the rye back in there.”

He also recommended installing hydrants and water lines. “Hauling water is way too much labor,” he said, adding that to pick up fencing and move it quickly, he uses a specially equipped four-wheeler.

Grazing covers works best when livestock are moved frequently, ideally multiple times a day, the two farmers said. Wilson is currently moving his cattle every five to seven days.

Cover crop forages tend to be highly variable, not only from year to year, but even within the same field. That can make planning difficult.

“It’s really a moving target for when you’re going to pasture it,” Sowers observed.

Mixed covers, whether they are grazed or not, appear to have a visible impact on soil structure over time, researchers are finding.

“Living roots feed the microbes that create the glue that keeps the soil structure together,” explained Dale Younker, a soil health specialist with the Natural Resource Conservation Service based at Jetmore, Kan.

Standing in one of Wilson’s fields, which was thick with forage sorghum, sunflowers, millet and other plants, Younker said it was possible to detect layers in the soil, almost like rings on a tree stump, indicating periods when the soil was more porous, due to microbial activity, and other periods when it was denser and flatter, after collapsing in on itself.

“I’m thinking the soil was collapsing in the fallow periods,” he said. “The longer we have a living root in the soil the healthier it will be.”

Meagan Schipanski, a CSU cropping systems specialist who heads the research project, said four years was barely enough time to begin observing long-term patterns and trends, but she hopes to put together a fresh grant proposal that will allow the research team to continue their work looking at the implications of replacing fallow with cover crop forages.