Real-world Soil Health Builders

How four farmers found the right cover crop to fix their soil’s problems:

Without question, cover crops can improve soil health—and better soil health means more efficient use of resources and the potential for higher yields. But failing to select the right cover crop will waste money as surely as dense, crusted soil wastes rainfall.

It’s not difficult to find farmers who skimped on the planning process and wound up disappointed with their cover crop. There are plenty of successful cover crop users, too. Their experiences can help you choose the cover that will set your soil on the road to better health.

“What stands out with successful cover crop users, versus those who struggle, is the successful ones had an objective,” says Farm Journal Field Agronomist Ken Ferrie. “They thought through all the steps of growing and managing their cover. That makes the odds of success go way up.”

Goals: Address Compaction to Increase Yields

Recently acquired by the operator; corn/soybean rotation; significant amount of highly erodible land; no-tilled for years by former tenant

To understand why yields weren’t up to par, Ferrie dug soil pits. Beneath the surface, substantial compaction or density layers from long-ago horizontal tillage were restricting root growth.

Deep vertical tillage would have removed the dense layers fairly quickly, but tillage was not acceptable to the landowner. The operator needed a cover crop that would function like a subsoiler—penetrate dense layers and leave biochannels for roots to grow and water to infiltrate.

When evaluating cover crop options, use a source such as the Midwest Cover Crop Council (www.mccc.msu.edu), Ferrie says. “You’ll probably find a number of crops that can penetrate dense soil layers, but only a few that will fit your climate and your time windows in the fall and spring,” he adds. “Not only must you get the crop planted in the fall, but to be most effective, many covers also need to grow in the spring. The amount of growth you see above the ground reflects the size of the root system.”

The planting window becomes shorter, and your cover crop options more limited, as you move from south to north.

In this case, the operator, who farms in central Illinois, could have used cereal rye, annual ryegrass, radishes or sweet clover to achieve his objective. Farther north, his options might have been limited to cereal rye, which can be planted later in the fall.

The farmer realized lengthening his planting window would increase his chances of success. So he switched from his 111-day corn hybrid to a 104-day hybrid and planted it first. Although it meant he had to use artificial drying, he harvested the hybrid at 27% to 28% moisture.

The cost of the cover crop included not only seed but potentially lower yield from the shorter-season hybrid and drying expense. However, it gave the farmer enough time to plant a mixture of cereal rye and radishes. Because the next crop was soybeans, the cereal rye had some time to grow in the spring, as well as in the fall. (The radishes winter-killed.)

After soybeans, the farmer considered the challenges of planting corn into cereal rye, and decided oats and radishes were a better choice. It’s best to plant as close to harvest as possible, or even before harvest.

“To lengthen his planting window, he may want to fly the cover crop seed into growing soybeans,” Ferrie says. “Our experience with aerial seeding has been hit and miss. Success depends on getting rain within two weeks of seeding.”

The farmer makes sure to have his cover crop seed on hand and a person designated to plant it while he’s still combining.

“Although we are not conducting side-by-side trials, our infiltration tests show water infiltration is getting better,” Ferrie says.

Goals: Store Nutrients, Protect Soil

Continuous corn, which the operator chops for silage; knifes in liquid manure

This operator has two objectives for his cover crop: capture and store excess nutrients, especially nitrogen, which he applies in early fall, and protect the soil surface from erosion.

In this farmer’s location, he could plant barley, annual ryegrass, cereal rye, millet, oats or wheat, perhaps with some radishes added to the mix. “With mixtures, just make sure everything that’s included accomplishes one of your objectives,” Ferrie says.

To smooth the surface after manure application, the operator tills about 7″ deep—using a modern hybrid chisel that provides full-width shattering at shallow depths—and levels with a vertical harrow. Then he broadcasts the cover crop seed. “If the weather is dry, he incorporates the seed with his vertical harrow,” Ferrie says. “But if he has good moisture, he doesn’t need to.”

If there is good growth in the fall, it gives the farmer a cattle grazing option. “In wet weather, he has to be careful the cows don’t compact the soil,” Ferrie notes. In the spring, the operator kills the cover with a herbicide or chops it for silage.

Grazing or chopping the cover probably won’t be allowed if you’re enrolled in a USDA program, Ferrie points out. “Some would say you should leave the cover crop residue to improve soil health,” he says. “But that was not this grower’s objective. Even though he harvested the crop in the spring, his soil was still protected from erosion, and he received a good return on his cover crop investment.”