Cover crops may be a forage alternative
Rest the grass, improve the stand is often recommended for rangeland. But what happens if a producer needs something for their cattle to graze on when a pasture needs a rest?
Grazing cover crops intensely for a short period may be the answer.
Alex Rocateli, Forage System Extension specialist at Oklahoma State University, is exploring cover crop options and what they can do to help with grazing dilemmas.
Rocateli said grazing cover crops does have some potential and benefits.
“Grazing ensures nutrient recycling,” Rocateli said. “The residue is still not nutrient available to the plants in the soil. Those residues need to be decomposed and then go back into the soil.”
The decomposition process and movement of the cattle help “work the residue into” the soil, which eventually improves soil health. The cattle leave behind their own residues too, which also improves the soil.
“Grazing may remove excessive material residue,” Rocateli said. “Here in Oklahoma we are planning on summer cover crops and after we are going to have wheat most of the time.”
Too much residue can be an issue when it comes time to seed wheat.
“This residue can be detrimental to the wheat,” he said “Sometimes it can bother the germination, can reduce the stand—so it makes the case of removing that excess residue with grazing.”
Increasing cattle gains on a “cheaper” forage type can happen, but cover crops often don’t have many inputs. Still a couple of things need to be considered in the bottom line.
“The producer can have some animal gain, and still get some money back to help alleviate the cost of seed and the tractor,” Rocateli said.
Grazing cover crops requires management. Cattle should not grub the cover crop to the ground. Rocatelli said there needs to be at least 90 to 100 percent of ground cover left after grazing to get the most benefits out of the process.
“Benefits are things like decreased soil moisture losses, decreased soil compaction and year after year we can be increasing soil health,” Rocateli said. “Of course it may take a little longer than a cover crop per se, but we still can hold some of the benefits.”
Rocateli said to achieve the 90 to 100 percent ground cover; a light to moderate stocking rate needs to be used when grazing. It’s not much different than for forage crops, he said. If one animal was housed in a big area, the animal can select every thing that’s available to it so that animal can just eat and eat. By increasing the number of animals, they tend to get good gains, but once a moderate stocking rate is passed and the animals start to get heavier, they’re going to start competing for forage and gains will decrease.
“They’re competing now for food, and they don’t have enough,” he said.
When thinking about gains, consider going by area. Regardless of the number of animals in an area, the gains could actually increase. However, as the number increases, gains will increase too, but to a certain stocking level.
At the end of the day focus on the net return. The best returns will be between light and moderate stocking. Rocateli proposes this with grazing cover crops.
“Go light to moderate to keep it above 90 to 100 percent cover, and we might still be having the benefits of cover crop,” he said.
In 2016, Rocateli started research trials in Perkins and Chickasha, Oklahoma, to look at different cover crops. He has high hopes for the project.
In the plots he had several varieties of cover crops, both grasses and legumes. Grasses included pearl millet, triple threat sorghum sudan and sorghum-sudan. The legumes included mung beans, forage soybeans and cowpeas. He also included two mixes—sorghum-sudan/cowpeas and pearl millet/mung beans. He also had fallow for a control.
The cover crop was terminated during late summer, and wheat was planted during the fall. Wheat was for grain purposes only. He also didn’t want to graze the subsequent wheat that followed the cover crop.
“I’m afraid that we’re going to have two things here—the cover crop effect in the wheat and also the grazing effect in the wheat grain,” he said. “Once I want to know exactly the affect of the cover crop, I don’t want to have this confound desirable there.”
Since this was a pilot study, Rocateli kept it small. They didn’t actually graze the cover crops because of expense, instead cutting it mechanically. He used differing stubble heights to simulate varying intensities of grazing.
Precipitation and weeds proved to be a challenge for the 2016 growing season, and soil fertility also played a significant role in the locations. Rocateli found no significant differences in the plots that kept good ground cover.
“In Chickasha we never grazed it, and numerically it looks like we had higher yields, but that was not confirmed,” Rocateli said.
The wet year also skewed his results some.
“It looks like if you have a wet year and we have especially a decent fertility in our soil, especially the grasses can catch up even when we have a severe grazing,” he said.
Severe grazing does make the ground a little vulnerable.
“When you do a grazing close to the ground after the grazing you’re going to have at least one week to 10 days that the soil’s not going to be covered,” he said. “So you can have some detrimental effects during this time.”
Rocateli isn’t making any conclusions after his first year of research, and would like to gather more input from farmers and ranchers using cover crops in their operations.
The Natural Resource Conservation Service has programs for a variety of cover crops. According to their website, cover crops have the potential to provide multiple benefits in a cropping system. They prevent erosion, improve soil’s physical and biological properties, supply nutrients, suppress weeds, improve the availability of soil water and break pest cycles along with various other benefits. The species of cover crop selected along with its management determine the benefits and returns.
Check with local NRCS offices if grazing of cover crops is approved in a particular area.