by Sally Colby
Soil and too much water is a bad combination for horses. Mud can result in slips and falls of both people and horses, and can quickly turn more hazardous if the temperature drops and hoof prints turn into frozen holes.
Mud harbors fungus and bacteria, leaving horses prone to issues such as rain rot and thrush. Excess pooled moisture provide ideal breeding grounds for mosquitos and other insects that transmit disease.
“A mud problem can be a drainage problem,” said Laura Kenny, Penn State equine educator. “This can be the result of soil compaction. Healthy soil should have lots of air spaces, and that helps with water flow.” Kenny added that compacted soil loses air space, preventing water entrance into the soil.
Low spots in a field, a high water table or broken drainage systems can contribute to mud. “We also see mud where there aren’t a lot of plants,” said Kenny. “A deep, dense root system helps anchor soil in place, and plants take up water.”
Kenny explained that a good recipe for mud includes soil and water, along with organic matter — any substance that contains carbon such as decayed plant or animal material. When manure, hay, wood chips or other materials break down and form organic matter in a paddock or dry lot, that mixture, along with soil and water, holds moisture. Areas where horses congregate, such as at gates, hay feeders, waterers and shed entrances, are most likely to accumulate mud.
Although there’s no single solution for a mud problem, horse owners can lessen or eliminate mud in heavy traffic areas or where horses congregate. Kenny suggests determining why mud is present in certain areas — is it a high-traffic area where horses compact the soil? Where is water flowing on the farm? Become aware of water flow patterns, especially after rain or melting snow, and determine where water originates and where it ends up.
Kenny’s first tip for mud prevention is to remove manure and feed from paddocks regularly. Hay fed outdoors should be kept off the ground when possible to prevent breakdown and accumulation of organic matter.
Another weapon against mud is roots. “Plant trees and water-loving shrubs in and around pastures,” said Kenny, adding that native species are ideal. “Once mature, a large tree can absorb up to 100 gallons of water each day. Evergreens use water in winter, so those may be a good option for some situations.” Prior to planting trees or shrubs, make sure they aren’t toxic to horses. Horses that chew wood should be fenced out from access to young trees.
Maintaining good pasture species helps prevent mud. The goal is a thick, dense and deep root system that collects and uses water as it anchors the soil. “Practice good pasture management,” said Kenny. “Take a soil test every three years and apply lime and fertilizer based on results. Don’t overgraze pastures — try a rotational system so pastures can recover for a couple weeks. Mow and control weeds, and overseed if necessary.” Bare spots should be seeded during the growing season so they’re well-established by fall and winter.
When it’s difficult to keep horses off pasture, a sacrifice lot may be the solution to preserving pasture grass. The size of a sacrifice lot depends on variables including number of horses, age of horses, and activity levels of horses. The behavior of individuals in a group can be factor in size — a group that includes a boss mare that chases others away from the hay requires a larger area.
“The lot should be a minimum of 20’ x 20’ for a single animal,” said Kenny. “Measure it, stake it out and see how it looks. You don’t want it too huge.” Consider factors such as convenience, whether the area requires lighting for late day feeding, access to water lines, access to pasture and manure removal.
In some cases, a heavy use, all-weather pad is necessary. The heavy use zone can include the entire area or just the areas with the worst mud. The mud is removed and replaced with a pad designed for good drainage. The base is large rock, which creates ample air space to help water drain downward. Pads are most often added near gates, at shed entrances or around hay or waterers.
“This isn’t a matter of simply dumping gravel on top of the muddy area,” said Kenny, describing a heavy use area. “If you do this, it will look nice for a little while, but over time, the soft mud will mix with the gravel and the gravel will sink into the mud and you’ll have muddy gravel.”
Proper construction of a heavy use area involves excavation and gentle sloping to direct runoff to a vegetative buffer. Kickboards around the edge help stabilize the area. Ideally, the upslope area outside the heavy use area should include a ditch to catch excess water. After excavation and grading, the first layer is geotextile, covered with large rock for the base layer, followed by smaller rock and a surface layer.
Options for the top surface include wood chips, but chips break down over time. Sand is suitable, but sand colic is a risk if horses are fed hay on the ground. Stone dust is good but tends to pack down to a very hard surface. Gravel works well, and should be 3/8” to 5/8” to prevent bruising.
Storm water management also helps prevent water accumulation and mud. Kenny said one inch of rainfall drops more than a half gallon of water on each square foot of roof, so a one inch rainfall on a 12’ x 24’ shed results in 172 gallons of water on the ground. Gutters are the easiest way to direct water from high use areas to a grassed area, and allow water to percolate slowly into the ground. Protect downspouts from damage by horses and equipment by surrounding them with heavy PVC pipe.
Always check state and local regulations prior to initiating water management or mud abatement projects. Some projects require engineering and design, especially if streams or other bodies of water are involved. County cooperative extension, USDA/NRCS and county conservation districts can provide technical assistance for water management projects.