Cashing in on cover crops

The benefits of cover crops for soil health and crop rotation are well known. The short-term financial impact of a cover crop is less clear, however. No-till farmer Josh Roe set out to measure the possible economic gain from harvesting cover crops by grazing and haying.

In north-central Kansas, where Roe backgrounds cattle and grows corn, soybeans, and wheat in partnership with his extended family, no-till cropping is widely adopted, but the growing of cover crops is less common.

"Farmers here are concerned about both the cost of establishing cover crops and them using a lot of moisture," he says.

Evaluating three cover crop treatments

An economist by training, Roe applied for and received a grant from the Sustainable Agriculture Research and Education program to evaluate three cover crop treatments: grazing, haying, and a control – where the cover crop was terminated without livestock being incorporated.

The three cover crop treatments were established in 2014 on a 60-acre field split into three sections. The cover crops were planted into wheat stubble on August 6.

The cover crop species and seeding rates for the grazing and control treatments included oats (30 pounds per acre), spring field peas (20 pounds), sorghum (1 pound), radish (3 pounds), and turnips (2 pounds). The radishes and turnips were left out of the cover crop mix planted for haying because of possible difficulties in getting hay to dry down for baling.

The total cost of establishing the most diverse cover crop mix came to nearly $67 an acre.

The cover crops grew rapidly in response to good rains. By October 14, when Roe took forage samples to analyze wet yield, the cover crops in the grazing and control treatments yielded 18 tons per acre on a wet basis.

On that same day, Roe harvested the hay from the haying treatment. After drying, the hay yielded 38 round bales, or 1.6 tons of hay per acre. He took a core sample from each bale and had the combined samples analyzed for forage quality. "The crude protein was 16%, for a total forage value of 150," he says. "This is equivalent to the forage value of medium-grade alfalfa."

When valuing the cover crop hay at the same value as alfalfa, the hay crop generated a significant profit. "At the time of the study, medium-grade alfalfa was selling for about $90 per ton," Roe says. "Costs per ton for establishing and harvesting the cover crop came to a little more than $73 an acre, leaving a net income of $16.60 per acre."

When analyzing the economics of grazing the cover crop, Roe focused on cost of gain.

Grazing started on October 19 in the cover crop paddock that was cross-fenced to create numerous smaller paddocks. The performances of two sets of cattle were analyzed. The first set of 58 steers weighed an average of 858 pounds and grazed for 26 days. The second set of 58 steers averaged 780 pounds and grazed for 60 days. The steers were supplemented with corn gluten.

"The steers performed well, gaining a little more than 183 pounds of gain per animal over 86 days, for an average daily gain of 2.13 pounds," Roe says. "Costs for the cover crop, supplemental feed and labor averaged nearly $124 per head, resulting in a cost of gain of 68¢ per pound. This was about 30% lower than the cost of gain on other cattle backgrounded on our ranch during the same time period.

"The cost of the corn gluten made up 60% of the total cost of the grazing experiment," he continues. "I believe we could further reduce that cost of gain considerably by reducing the
supplemental feed."

Cattle grazed about 75% of the cover crop biomass, leaving 25% as residue covering the soil surface. They were also penned during wet conditions, when their hooves could potentially roughen the softened soil surface. During these times, the cattle were fed the bales from the hayed cover crop plot. "Having the option of feeding hay during certain periods gave the system a lot of flexibility," Roe says.

Clear advantage

The haying and grazing treatments used in the study both yielded a clear economic advantage over the control treatment, when the cover crop went unharvested. "Where the cover crop was left alone, costs were nearly $67 per acre with no measurable fertility or yield advances in the following crop," he says.

The subsequent corn crops grown on all three cover crop treatments showed no significant differences in yield. Corn yields on the cover cropped plots matched those of corn grown on fields not previously producing cover crops.

"Despite significant setbacks with a wet spring, the corn grown in the cover crop plots yielded 135 bushels per acre," Roe says. "The field we own across the road that did not have a cover crop yielded 137 bushels per acre. Therefore, we cannot conclude that the cover crops had any adverse yield impacts."

One year's worth of cover crop production could be too brief a time for potentially significant increases in biological activity in the soil to account for yield increases in subsequent crops. The cover crop residue's physical interruption of soil degradation is more immediately visible.

"After we planted the corn into the field previously growing covers, we had 9 inches of rainfall in two hours, with significant hail," Roe says. "Although gully erosion occurred in certain areas of the field, it was evident that the cover crop residual greatly reduced sheet and rill erosion."

Expanding the experiment

The information Roe gathered while evaluating three treatments of cover crop production convinced him that planting cover crops for haying or grazing can be profitable and will preserve soil at the same time.

A recent purchase of 200 acres by Roe and his wife, Adassa, gives him a chance to commit the entire acreage to cover crops for grazing. "I hope to keep track of the data on cattle gains," he says.

"When I look at the economic activity we generated by growing cover crops for haying and grazing vs. growing no cover crop at all, the differences are dramatic," Roe says. "There are certainly costs and labor involved in growing cover crops. But the value of haying and grazing the cover crops also represents a sustainable intensification of management that is good for the soil over the long term."