Amber Friedrichsen, Hay and Forage Grower 2021 editorial intern
(Previously published in Hay & Forage Grower: June 15, 2021)
As the saying goes, the grass is always greener on the other side. But is the grass always mowed on the other side? Deciding whether or not to mow or clip pastures can leave farmers stuck on the fence.
Possible reasons for mowing are site-specific. Producers sometimes wish to eliminate seedheads, promote even grazing, and provide weed control. However, the costs of mowing can outweigh these benefits, wasting farmers’ time and money.
As forages mature, their palatability and nutrient availability decline. Mowing pastures is one way to remove stems and seedheads from plants and set them back to a vegetative state. Amanda Grev with University of Maryland Extension says promoting new leaf material is advantageous for the plant, as well as the grazing animals.
“New leaf material will be higher in quality for livestock and will continue to capture sunlight and provide energy for the plant,” the forage and pasture management specialist says. “Keeping plants in a vegetative state not only maximizes forage quality, but also maintains a higher growth rate and stimulates tillering and regrowth.”
It is not cost effective to mow pastures if there aren’t enough seedheads present. Grev encourages farmers to get out of the tractor and evaluate their crop from the ground to justify their mowing decision.
“Looking at a field from a windshield view often gives off the appearance that there are a lot more seedheads present than there really are,” she says. “Be sure to go through the field and look at seedhead density from above. You may find that there are fewer present than you initially thought.”
Even the playing field
Another reason to mow is to even out forage that has been selectively grazed by livestock. Plants that animals eat around will continue growing and become too mature. This creates an unequal distribution of forage growth and quality throughout the pasture.
Uneven grazing is more common in continuously grazed pastures than rotationally grazed systems. Grev says one way to promote pasture uniformity without the use of a mower is to establish a system with small paddocks and to frequently rotate livestock.
“Although this requires additional management, the return on this is less clipping, fuel, and time spent mowing,” Grev says. “In the long run, improving your management with rotation will likely be more viable than clipping underutilized areas.”
Weeding out competition
If heavy weed pressure is a problem, mowing can be a mechanical form of control. Different weeds have different responses to being mowed, though, and the type of weed can impact results.
Mowing perennial weeds won’t kill them right away, but it will demand more energy from the plant for regrowth. As its energy reserves are depleted, the weed will be weakened over time with frequent mowing.
Annual weeds, on the other hand, may not be as threatened by a mower. The presence of these weeds can indicate poor ground cover. While clipping annual weeds offers short-term control, establishing a better cover will be more beneficial in the long term.
Grev points out that mowing as a form of weed control comes with many hidden costs. Consider the time it takes to mow along with fuel, maintenance, depreciation, and storage of equipment. In addition to cost, Grev also says mowing weeds can remove desired forage and reduce the amount of grazable dry matter per acre.
Pinkeye and other problems
Forages do not cause pinkeye, but excessive seedheads can aggravate the infection. Mowing pastures can help control pinkeye in cattle but is not necessary unless an outbreak has occurred.
As far as human eyes go, mowing pastures simply to improve aesthetics is not a valid reason. According to Grev, trying to maintain a lawn-like appearance can be expensive, and cutting forages too short can take away from their environmental potential.
“Taller forages produce more live roots, which can provide some drought resilience,” Grev says. “They can also help keep the canopy closed, shading out some weeds and keeping soil surface temperatures cooler and wetter.”
Grev summarizes that mowing can be useful when benefits outweigh costs. However, some farmers may be better off focusing on other things to improve conditions in their pasture rather than spending time and money on a mower.