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Patience, rotation key to pasture management

By Staff | May 12, 2015


The coming of spring and warmer temperatures means more pastures will be seeing livestock soon.

Beth Doran, an Extension beef program specialist for Iowa State University, said that as of April 28 pastures are in good-to-excellent condition.

“Cool weather has slowed pasture growth,” Doran said.

Quoting the Iowa Department of Agriculture and Land Stewardship April 28 report, Doran said 12 Northwest Iowa counties are experiencing abnormally dry-to-moderate drought conditions: “We need heat and moisture.”

Doran said conditions are also dry on the northeast and southeast sides of the state.

With pastures in good shape now and so many counties experiencing at least some degree of drought, she said the main concern to managing pastures this year will be patience in letting grass grow and scheduling rotations.

“The biggest thing producers can do is avoid turning cattle out onto grass until the forage is six to eight inches tall,” said Doran. “If you must graze before the grass is that tall – or if your pasture stand is less than normal – consider reducing stock rates by 20 to 30 percent.”

Doran said overgrazing is a common problem and that managing a pasture is both a science and an art.

“Grazing is not easy,” Doran said. “You’re trying to manage both animals and plants, and trying to make the two work together.

“If you haven’t done rotational grazing it’s good to start off on a smaller level such as three or four pastures.”

Doran said for continuous grazing, a good ratio of cows to pasture land is 2 to 2.5 acres per cow-calf pair if conditions are normal for moisture and temperature.

“This number varies,” she said. “In some parts of Iowa that are more hilly, moisture may be limiting and it could take up to 4 or 5 acres per pair.”

Doran said with rotational grazing the number of acres is reduced, but management and weather are key to its success.

“Over the whole grazing season,” she said, “30 days of rest (no grazing) may be required for the forage to regrow and before cattle can be returned to their initial paddock.

“This is if Mother Nature cooperates with temperatures and moisture.”

She said sheep grazing on pasture could require closer attention to pasture grass than with beef because the split-lip mouth structure of a sheep allows them to graze closer to the ground, creating the potential for stunted grass growth if overgrazing occurs.

“You have to watch them closely,” Doran said. “In the fall, you have to pull them off of the pasture more quickly than cattle in order to allow the pasture to regrow and not overwhelm the grass.”

Doran said pasture grass can reach optimum health levels by managing fertility inputs, considering both soil fertility and the probability of rain.

“Application of nitrogen will stimulate spring growth,” she said, “especially in grass-based pastures.

“But the level of nitrogen may depend on soil moisture. If spring moisture is limited, it may be more economical to apply a modest amount of nitrogen now (40 pounds per acre), and assess the likelihood of moisture during late spring and summer.”

Doran said if moisture levels improve, an additional 30 to 40 pounds per acre could be applied during late summer.

She said if moisture gets short or temperatures are warm, pasture stocking rates may need to be reduced.

“It would be good to think ahead right now about whether or not to plant a summer annual such as millet or sudangrass to have as an emergency crop,” she said.

Doran said common pasture weeds may be more prevalent due to past conditions, such as drought, cool weather and overgrazing.

She said overgrazing weakens the ability of grasses and legumes to grow and complete, making it easier for weeds to grow.

The bottom line, she said, is to avoid overgrazing in the fall in order to keep pastures healthy for the long term.

“(Heavy grazing) might get you through the year, but you’ll face the consequences in the fall of the year,” Doran said. “It won’t come back as fast and it won’t be as productive.

“I’ve seen it in a lot in pastures that carry a lot of thistles. There’s a good correlation as to how hard it was grazed.”

Doran said overall there is less pasture since many of those acres were converted to row crops.

Still, she said, pastures need to be managed as carefully as row crops.

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