Farm Talk

Crops

July 6, 2010

Nipping seed heads early eliminates the need to mow pastures in July

CNHI

Parson, Kansas — Mowing pastures to remove grass seedheads has become a July ritual for pasture managers. Now that chore can be cut.

Rob Kallenbach, University of Missouri Extension forage agronomist, says that extra expense can be eliminated by nipping or clipping pastures in late April or early May. “Having to mow pastures in July indicates earlier management failure.”

Removing seed stalks of grass plants before the seed emerges can provide seedhead-free grazing all summer long. Seedheads form and emerge in grass pastures by mid-May across most of Missouri. By July, any unclipped grass gives low-quality grazing.

“If pastures are mowed in July, go all the way, cut it off short,” Kallenbach said. Many farmers mow pastures and leave eigth- to 10-inch stubble, cutting only the seedheads. The best practice is to remove all dead material, leaving a 2.5-inch stubble.

Early removal of the seed sheath by grazing with livestock or mowing for hay solves an old problem, Kallenbach said. Grass forms only one seed stalk per tiller each year. Once the seed is removed the grass remains vegetative, growing only leaves the rest of the year.

Early seedhead removal, before it emerges, is part of Kallenbach’s new plan for intensive grass management that includes making hay in April. When he first suggested haying in April, many farmers expressed doubts. “A lot more hay is baled in July when hay is well past prime than in May when hay is most nutritious,” he said.

“Making hay in April has been an attention-getter,” Kallenbach admitted. “If people start planning to cut hay in April, they might get it done by early May. Farmers who made hay in April this year are now believers.”

Hay cut early is less likely to be rained on. On average, rainfall is heavier in May and June than in April.

A pasture showing seedheads indicates that forage quality has dropped, Kallenbach said. “A grass plant’s only objective in life is to make seed to ensure survival of the species. Once seed forms, the plant stops growing.”

In biological maturity, the grass transfers nutrients from the leaves into the seed. Once seed matures, the plant has the same feeding value as straw, he said. However, grass hay harvested before seeds set can have the feed value of alfalfa hay.

Seedheads are a big problem in pastures of tall fescue. The ergot alkaloid that causes fescue toxicosis becomes concentrated in the seedheads. Ergovaline in infected fescue causes heat stress in grazing animals. That reduces gains, lowers milk production and causes breeding failure.

Livestock don’t want to graze mature fescue, Kallenbach said. Removing the seed stalks, heads and stems allows fresh grass to emerge, providing good grazing later into the season.

Mowing pastures in July won’t be necessary if pastures are managed early in the grazing season to remove emerging seedheads before they create problems.

With good management, forage quality will improve all season long.

Farmers using the MU software for grazing wedges are discovering the difference in pasture performance. They measure pasture growth weekly and record the dry matter growth in each pasture. When recorded on the MU website, the resulting wedge shows which paddocks should be grazed or mowed.

Grazing wedges, first used by dairy producers, are now being used by beef herd owners. See example wedges at plantsci.mis souri.edu/grazingwedge/.

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