IntheKnow switchgrass

In the Know: Forage Height to Promote Growth

IntheKnow switchgrassNative grasses like switchgrass need to be maintained at taller heights to promote forage growth. • Photo by Peggy Greb/United States Department of Agriculture

Horses graze closer to the ground than cattle, which makes overgrazing in horse pastures a problem. To promote growth, a minimum forage height should always be maintained. That height is dependent on the grass species. For example, in Texas, Bermudagrass and Bahia grass should have a minimum height of 3 to 4 inches.

Native Texas pasture grasses, such as switchgrass or Indiangrass, grow in bunches rather then creating a dense sod that covers the entire soil surface like Bermudagrass does. Bunch grasses have a higher growth point than Bermudagrass, so a stubble height of at least 10 to 12 inches should be maintained. Due to the higher growth point, native grasses are less tolerant of grazing abuse than Bermudagrass.

Forage growth and regrowth is dependent on the amount of leaf on the plant. The forage uses its leaf area to capture sunlight and, via photosynthesis, produces its own nutrients.

“You need leaf area for photosynthesis, so the more leaf area you leave on the plant, the greater the plant’s capability for photosynthesis which will help the plant produce more leaves and develop a better root structure,” said Dr. Vanessa Corriher-Olson, associate professor and forage extension specialist at Texas A&M Research and Extension Center in Overton, Texas. “The root structure is responsible for reproducing leaves if that plant is grazed by using stored carbohydrates in the root structure to produce the new leaves which can then photosynthesize. The root structure is also responsible for persistence of the forage.”

Nutrients such as nitrogen, phosphorus, potassium and water are pulled out of the ground by the root system. Shallow root structures make the plant more susceptible to long-term dry conditions.

“With a deep root structure, even if the top two to three layers of the soil are dry, there may be soil moisture deeper down that the root can access,” Olson said.

Contact a local extension office for advice on stubble heights for grass species in your area.

Read more about pasture maintenance and irrigation in “Dripping with Success” in the June 15, 2016, issue of Quarter Horse News.

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