Pasture growth needs warm sunshine, good management, MU specialist says

COLUMBIA, Mo. – Cool spring weather delays grass growth this year, forcing cow herd owners to feed hay long past winter.

Rob Kallenbach, University of Missouri forage specialist, hears two frequent complaints: The grass is not growing. And there are more weeds than usual.

The first is due to a cool spring. The second is due to a hot, dry summer last year.

“For grass to grow, we need warm sunshine,” Kallenbach says. “There is plenty of moisture in the soil, in contrast to the drought last summer.”

Farmers measuring grass growth in their grazing paddocks find one-third the growth of just one year ago.

“Last year in April, growth averaged 90 pounds of dry matter per day per acre. This year, growth is less than 30 pounds per day,” Kallenbach says.

Pat Guinan, MU Extension climatologist in Commercial Agriculture, says it’s the coolest March and April in 17 years. Across northern Missouri temperatures average as much as 6 degrees below normal.

“Air masses from the north cross a very large snow pack in the northern Great Plains,” Guinan says. “That snow cover extends to the Arctic.”

The six-to-10-day forecast calls for temperatures to return to near normal.

“With warm weather, pastures will jump,” Kallenbach says. “There is no shortage of water over most of Missouri.”

Grass recovery will be slow, however, on pastures grazed by cattle all spring. Cattle nip off leaves that create energy for regrowth. Sugars from photosynthesis make rapid growth.

Photosynthesis creates leaf elongation and develops side tillers that create more leaves.

“If there was ever a time for rotational grazing, this is it,” Kallenbach says. “Graze the grass down to a 3-inch stubble, remove the herd, and let the grass rest for 30 days.”

A recipe for killing a pasture is to put it through a drought, then graze it hard the next spring without time for recovery. Then, if it is hit with another dry summer, just kiss it goodbye, the forage specialist says.

“The aim is not just grazing in April, but also through June and again in the autumn. Grass management is required for stands to fully recover,” Kallenbach says.

Some farmers have confined their cows to a smaller pasture for continued hay feeding.

Farmers without hay have been buying one or two bales at a time to feed their cows. They keep thinking grass growth will start and they won’t have to buy hay another day.

“Grass grazed short will take longer to recover from bad management,” Kallenbach says. “Cows not being fed hay are eating a lot of scenery, which is not very nutritious.”

Weeds in pasture are filling bare spots caused when grass died in the drought, he adds.

Winter annuals, such as henbit and chickweed, are nature’s way of filling a void. The seed was already in the soil, waiting for a chance to grow.

Cows will graze chickweed, which is nutritious. The only problem is that there is not much growth there. Cattle avoid henbit.

The concern is what will fill those bare spots after winter annuals are gone, Kallenbach says. If crabgrass grows, that is good. If horse nettle grows, that’s not good. Tall weeds shade grass and reduce growth.

Some grasses, such as fescue, can be aggressive in reclaiming bare spots, given some good grass-growing weather.

Kallenbach answered questions on the weekly teleconference for MU Extension regional agronomists. The regional specialists in county offices provide local answers to grazing questions.

The teleconference is part of the MU College of Agriculture, Food and Natural Resources.