Overgrazing is grazing a plant before it has recovered from a previous grazing. Overgrazing can be damaging, not only to the natural balance of grazing lands, but to producers' bottom lines, as well. To avoid overgrazing, managing livestock on grazing lands requires graziers to be flexible and understand the complex soil-plant-animal relationship involved.
"Grazing is a balancing act," says Dave Pratt, owner of the Ranching For Profit School, "Between animal needs, forage supply, wildlife needs and your own needs."
Grazing lands are governed by a multitude of biological processes and systems. When these systems become out of balance, overgrazing can occur.
Pratt explains, "Overgrazing is grazing a plant before it has recovered from a previous grazing."
Overgrazing is a factor of time, not animal species or numbers. It can happen in continuous or rotational grazing systems. According to Pratt, this occurs two ways – animals staying in a paddock too long or coming back too soon.
During overgrazing, animals reduce plant leaf areas, decreasing plants' ability to intercept sunlight and grow new leaf material. This reduction in turn slows down plant regrowth, drains energy reserves, and if left unchecked, can lead to eventual plant death. Weakened root systems decrease soil stability and plants become more susceptible to drought and weed pressure.
A common indicator of overgrazing is animals running short of pasture. Species composition of overgrazed pastures is predominated by short-grass species such as bluegrass. More palatable tall-grass species slowly become sparse to nonexistent over time as they are repeatedly grazed. Plant spacing and bare soil areas may also increase leading to greater risk of soil erosion and weed encroachment.
To prevent overgrazing, taking plant-growth rate, natural processes of grazing lands and animal grazing behavior into consideration are essential. There are many styles of grazing management to choose from: rotational, mob, cell or holistic, for example. It is up to the grazing manager to choose which one will work best in each situation.
Whatever style is chosen, a well-designed grazing plan bases rotations on changing plant-growth rates throughout the year. In addition, animals are moved regularly. This style of management mimics the natural processes of wild migrating herds of large herbivores which evolved in unison with grasslands eons ago. When used properly, managed grazing has the potential to greatly improve grazing land conditions through improved soil health and forage production.
New York grazing specialist, Troy Bishopp, advises producers to be conservative and realistic in their grazing planning.
"Take it one day at a time, keep asking yourself the 'what-if' questions and have clear goals as to what they want to achieve," says Bishopp. "Start with something you can really manage instead of going beyond your means."
He recommends producers use a grazing chart or planning worksheet to assist in the planning process. In addition, Bishopp says, "It's imperative to walk the land and 'ground truth' (i.e.: know) what you really have before you get all giddy grazing and then run out of grass halfway through the season."
Factors that will be used to design a managed grazing plan will include recovery periods, graze periods, stocking rates and season of use, among many others.
It's important to have a grazing plan. Recovery periods, also known as rest periods, should be adjusted with changes in plant-growth rates throughout the year. During slow growth, recovery periods should be long with short grazing periods and vice versa. This allows managers to take advantage of livestock's selective grazing behavior while maintaining adequate recovery time for plants.
"Eight to 10 paddocks can stop overgrazing," says Pratt, "But it isn't enough to get the graze periods short enough for top animal performance."
Pratt suggests 16 paddocks or more may be needed to keep performance high. Number of paddocks needed in each circumstance will vary with animal numbers and amount of forage available.
As with graze and recovery periods, stocking rates should be fluctuated to match seasonal changes in pasture carrying capacity. Matching the forage supply to the herd's requirement will help prevent overgrazing. Consolidating herds and using increased stocking density increases "herd effect," improving pasture conditions and promoting more uniform grazing.
It is important to note, even in the most well-designed, managed grazing systems, sometimes overgrazing still occurs.
"Expect to make mistakes," says Pratt. "You will get the recovery period too long or too short, more likely. You will get the graze period wrong at times. You will graze some places harder than you want or than you expected."
"That's OK as long as you learn from your mistakes," Pratt adds. "And do your best to avoid making them a fourth or fifth time."
To help things go right the first time around, Pratt suggests producers lay their economic and financial foundation first.
"Know your margins," he says. "Keep overheads low. Know the turnover you need. Monitor cash flow. Make sure you put your capital in things that make money, not fixed assets."
Additionally, producers should create enterprise mixes that allow for easy destocking annually and seasonally in cases such as drought.
On the management front, Bishopp offers the following suggestions to avoid an overgrazing situation:
- Have feed on-hand or stockpiled in the spring so you are not forced to graze too early.
- Use a grazing chart to plan out a rotation.
- Monitor grass growth and rainfall.
- Maintain proper pasture residuals for your area.
- Use your "gut instinct" on pasture management decisions in dry weather conditions.
- Have a contingency plan in place before you need it.
It is important to realize mistakes such as overgrazing are a reality. But, with good planning and proper grazing management, pastures can be healthy and productive ensuring grazing livestock are also healthy and productive. Producers with sound grazing management strategies in their arsenals will be better prepared to deal with these issues when they arise.
Authored by Jesse Bussard
, an agricultural writer based in Bozeman, Montana.
Grazing planning worksheets recommended by Bishopp may be downloaded here:
Many NRCS and university grazing planning spreadsheets are available on the web as well. Contact your local NRCS grazing specialist or university extension forage specialist for more information.
Ranching For Profit website:
Troy Bishopp's website: