Design pastures for more grazing and fewer weeds

By Ellen Nelson
Larimer County Weed District

A dry fall has taken a toll on pastures in northern Larimer County. Rain and cool weather expected in August and September did not materialize. The typical growth of cool-season grasses has not occurred.

If you are managing your pastures, allowing adequate time and opportunity for pasture recovery, this lack of precipitation plays havoc with your management plans. Usually a pasture is rested three to four weeks and precipitation provides moisture for re-growing leaves and replacing energy from plant roots. Without moisture, no re-growth occurs; the recovery period lasts until a pasture receives adequate moisture. This could take months or, during drought, a year before re-grazing can occur.

This is fine on an intellectual level, but as a horse owner, you are faced with the reality that animals have to be somewhere; you can't put them in suspended animation while the grass grows.

A flexible pasture design provides options for managing these common climatic anomalies. An important feature is a confinement, or sacrifice area. A small corral, less than one-half acre, is used to confine animals when they are not grazing. It could double as your riding arena, or may be smaller individual paddocks. These areas are heavily used and lacking vegetation. You need to feed your animals when confined. This confinement area is your first line of defense in managing pastures to prevent overgrazing and to insure recovery after grazing.

If you have a smaller acreage, or do not have irrigation, your animals will spend more time in the corral than grazing. This is because one acre of typical dryland pasture in northern Larimer County, on average, produces enough forage in one year to feed a horse for less than two weeks. On small acreages, you will purchase most of your forage, using your pasture as a turnout for an hour or so every other day. Consider planting a tougher, less palatable grass, like crested wheat, that tolerates some hoof action. Feed horses before turning them out and don't turn out on wet ground.

If you are fortunate enough to have more than 40 acres or irrigation water, you may produce enough forage to feed a horse for almost a year. Even so, savvy pasture design benefits you when weather doesn't cooperate. Instead of a single 40-acre pasture continuously grazed, consider four 10-acre pastures grazed for short periods. Graze pasture #1 for several days then rest it while animals are cycled through pastures #2, #3 and #4. After pasture #4, the animals are rotated back to pasture #1 and through the pastures again. When the number of animals, time of year and available moisture are in harmony, the plants in pasture #1 have time and opportunity to regrow their leaves and replenish their roots. However, with minimal precipitation, pasture #1 may not be ready for re-grazing. This is when a sacrifice area is invaluable; animals are returned to confinement until the pasture next scheduled for grazing has sufficient moisture and time to recover.

A guideline for how long to graze and when to re-graze is the "second bite" rule: Remove animals from pasture before they take a second bite of a plant and allow plants adequate time to regrow before re-grazing. No design provides optimal moisture or temperature to guarantee recovery periods. Some designs provide stockpiling forage for when grass growth is limited, as well as opportunities for grasses to rest and recover.

A simple modification of the four-pasture design is five or more smaller pastures. Begin grazing pasture #1 when grass is 8 inches to 16 inches tall in spring. Rotate through pastures #2, #3 and #4. Do not use pasture #5; save it for a reserve if the weather doesn't cooperate later in the season. Use your confinement area and monitor recovery in pastures before rotating animals.

If the weather cooperates, you may not need pasture #5. This gives grass a wonderful opportunity to replenish root material and contribute seed to the soil seed bank to compete with invasive weeds. This extended rest period is an excellent tool for preventing noxious weeds from invading your pastures. The rested pasture also provides winter grazing. As always, don't graze too close to the ground, leave adequate stubble to catch and hold valuable winter precipitation in the form of snow, and leave plenty of vegetation at the plant crown for adequate insulation during the coldest winter periods.

The following year, select a different pasture as your "reserve." Rotate animals through the remaining pastures, using your confinement area as needed. Modify the order you use your pastures; don't graze the same pasture at the same time every year. If you always graze pasture #1 in the spring, cool season grasses in that pasture will always be under grazing pressure when they are trying to grow and produce seed.

You may decide it is simpler for your horses to graze wherever and whenever they want. However, a pasture that is stressed and overused is an invitation for invasive weeds. The best way to prevent increasing weed populations in your pastures is to have a healthy stand of grass.

Rotational grazing is one method to promote healthy pastures. If you need help identifying plants or want advice on controlling weeds, contact the Larimer County Weed District at 498-5768 to set up a site visit with a weed specialist.