Slow pasture grass growth irks farmers, cool weather only part of the problem
Writer : Duane Dailey
COLUMBIA, Mo. – Grass growers ask, “Why doesn’t my grass grow this spring?”
“It’s the cool weather and a whole lot more,” says Craig Roberts, University of Missouri Extension forage specialist.
Delayed crop planting and slow grass growth were common topics in the weekly agronomy teleconference for MU Extension specialists.
Best pasture grass grows in 70-degree weather, Roberts said. That’s day-and-night average for 24 hours. It’s not a day with 70 degrees for two hours in the afternoon.
A bigger problem occurs when cows grub pastures into the ground with early grazing. That happens when herds are turned out to pasture at the first sign of growth.
“We’re talking grass 1 inch tall,” Roberts said. “The pastures look like pool tables.” Short grass leaves don’t have enough photosynthesis to create new growth. Early grazing consumes stored carbohydrates held in reserve to start spring growth, Roberts told field specialists.
Questions were asked about spreading nitrogen fertilizer to make more grass. “Maybe some, but not much,” Roberts replied. In normal years, use no spring nitrogen, he says. A spring flush of growth makes more grass than cow herds can eat. Early growth matures and goes to waste.
“This year use limited nitrogen,” Roberts says. “Normally we’d say 40 pounds of N per acre, but this year no more than 20 pounds.”
That may require farmers to spread the fertilizer. “Commercial applicators won’t want to come out for such a limited sale,” he said.
Applying nitrogen in spring has too many downsides to be used regularly. The N makes too much growth. Worse, N applied to toxic tall fescue, the most common pasture grass in Missouri, spurs development of alkaloid toxins in the grass. Toxins cut animal growth, milk and reproduction.
Also, adding nitrogen crowds out legumes desired in pasture mixes.
Better weather outlooks with higher temperatures lie ahead. Plus, plentiful rain makes for grass growth.
“Moisture that’s bad for crop plantings is good for livestock producers turning herds out to pasture,” Roberts said.
Management-intensive grazing (MIG), including rotational grazing, allows better use of sparse grass. MIG boosts production by about one-third.
Managed grazing is taught at grazing schools held by MU Extension in cooperation with the USDA Natural Resources Conservation Service and county Soil and Water Conservation Districts.
Roberts urges herd owners to enroll.
Regional MU Extension agronomists give advice to farmers.