Manage Summer Pastures

Manage Summer Pastures

Photo: Megan Arszman

Assess your geographic region, plant species, soil, and plant stand to help ­maintain your pastures' (and your horses') health.

This past summer I stood in the blistering early August sun surveying my Kentucky pastures. Grass was nearly nonexistent and a few straggling thistles and ironweeds stood tall. My cattle and horses wandered in search of anything palatable, kicking up dust with every step. Two previous years of record-breaking drought had decimated the fields, and despite a wet spring they looked like the African savanna.

Have you ever had one of those epiphanies where you realize that what you had taken for years as indisputable fact was wrong? I was a veteran of the "Back to the Land" movement of the '70s and a believer in nonchemical, minimum fossil fuel land management. I used no herbicides or fertilizers since I had plenty of ground for the number of animals that would graze upon it. Our pastures were large open fields with trees here and there for shade, and there were several natural water sources and a float waterer near the barn. The grasses were primarily fescue with a mix of natural grasses and a little orchardgrass that was planted sporadically by previous owners. The pastures seemed perfect.

About the only effective management technique I practiced over the years was bush-hogging the fields to about six inches just after the thistles and broadleaf weeds formed flower heads, but before seed formation. The plants had put so much energy into reproduction that mowing at this stage reduced their seed production dramatically. Old pastures comprised of 25% thistles, multiflora rose, and other noxious (invasive and rapidly spreading) weeds dropped to less than 5% without expensive and environmentally unsafe pesticides. The grasses filled back in quickly.

Then the weather got weird. Some of the 100-year-old trees have died amidst the more frequent severe droughts and harsher winters. The climate seems to range from very wet to very dry, with very little between. I had a vague awareness of rotational grazing techniques from friends who were "real" farmers and made their living from the land, but because of our acreage I thought I'd never have to put up a bunch of fences and move livestock around constantly. I was wrong.

The kind of constant low-pressure grazing that I was managing is the antithesis of nature: At one time herds of herbivores ranged large areas, eating down the vegetation quickly before moving on, allowing plants to recover. Plants, particularly grasses, evolved to thrive with this routine, as did organisms that maintain soil health. Rotational grazing as a part of smart summer pasture management should mirror these conditions as closely as possible.

Assess Your Situation

In an area like Central Kentucky, with fine clay soils on top of hollow limestone karst topography, drainage is not a problem. However, rainy periods can cause destructive compaction of the soils, giving them an almost rocklike consistency. Subsequent rainfall runs off instead of soaking in, making it difficult for forage to develop roots. When dry weather sets in, the combination of hard ground and weak, shallow rootstock results in high plant mortality as close-grazing horses clip plants to the ground. This prevents shading of the soil by the plants, further decreasing moisture retention. It's a cycle I see now as occurring most summers on my farm. Breaking this cycle involves improving those things that affect pasture quality: plant species, age and height of the plant stand, rain availability, soil depth, type, and fertility.

Plant Species

Fescue is a good cool-season grass, but horses don't find it palatable in the summer--it appears to be more palatable when its taste sweetens after frost, making it more attractive to livestock during colder months. Another downside to fescue is that the endophyte-infected KY 31 species can cause reproductive problems in mares during late pregnancy, so mares should not have access to this forage (either hay or pasture) in the last 60-90 days of gestation. Planting endophyte-free fescue, however, reduces the problems associated with the fungus, and transmission from infected to noninfected plants is minimal.

"There are novel (nontoxic) endophyte fescue varieties available," says Philip S. Shine, a University of Kentucky Forage Breeding Research analyst. However, "Endophyte-free fescue does not persist as long as endophyte-infected fescues. The endophyte within the plant extends the longevity of persistence." There are better summer mixes for horse pastures such as orchardgrass with alfalfa or clover, and Kentucky bluegrass, which does well in soils with lower pH levels and available phosphorus and potassium. Farther south, Bermudagrass and crab grass are good heat-tolerant grasses. To the north, Birdsfoot Trefoil can be substituted for alfalfa as the pasture legume component. Consult a local extension agent or research grasses suited to your region's summer ¬season.

Also, monitor the types of volunteer species that grow in your pasture. Often, native grasses appear in patches and might have better drought or insect resistance than introduced species. Keep an eye out for plants such as Johnsongrass, sorghum, sudangrass, and certain broadleaf weeds, which can be harmful to horses and should be controlled/discouraged--typically with well-timed mowing. Johnsongrass and Sudangrass, for instance, can accumulate prussic acid, which is poisonous to horses. These plants are not palatable, so horses will not ingest them in dangerous quantities as long as suitable edible forage exists elsewhere in the pasture. A local extension agent can help you determine what volunteer noxious weeds grow in your area and the best control methods.

Age and Height of Plant Stand

In our case the grass stand is old and worn so we reseed annually, starting with the areas that need it most. The pasture rotation process preserves the plant stand and allows new grass to grow. Keep in mind that forage kept four to 10 inches tall provides maximum nutrition for your horses, so turn out animals on a pasture or paddock with grass height of around 10 inches and allow them to graze it down to four inches. Rotating them off the ¬paddock/pasture at that point allows the area to rest and accommodates a four-week regrowth period while horses are on another field. Time and experience, or your local extension agent, will help you determine the size and quantity of paddocks needed for an effective rotational grazing program at your farm. You might have a sufficient number of paddocks divided by permanent fencing, but we construct them using solar-powered electric fencing within existing larger fields. If your water sources are not centrally located, you might also need to create lanes to access paddocks.

The positive effects of rotation on your pastures are cumulative. Without damage from overgrazing, the plants provide shade to the soil, which remains friable (easily crumbled), allowing better water retention. This leads to stronger and deeper root development and a healthier microorganism base to break down nutrients that the plants can use. The lower part of the plant that remains is still vigorous enough for more rapid regrowth.

In periods of extreme drought offer your horses free-choice hay access to preserve remaining plant stands. A sacrificial paddock could also be used, thus reducing damage to the entire field.

Horse owners in areas of the country experiencing ample rain who have particularly lush pastures might also consider establishing a sacrifice area if they have horses prone to metabolic problems.

"Founder is an all-too-common and sometimes deadly problem (in areas) where forage tends to be too rich and plentiful," says Dan Bowling, DVM, owner of the Animal Hospital of Nicholasville, in Kentucky. "The best thing for a horse that is turned out most of the time (on these types of pastures) is a worn pasture where he has to move around to find limited food." This mirrors the environment in which horses evolved.

For owners concerned about farm appearance, he suggests setting up this type of pasture or sacrifice area "out back," where bare spots won't be as unsightly.

Soil Depth, Type, and Fertility

A soil test kit, available from your local county extension agent or a farm supply store, can help you determine which grass variety will perform best in your pastures with limited soil amendments such as lime and fertilizers. Try to maximize the soil's health and potential, rather than change it into something it is not. I can't turn my clay soils into sandy soil; however, I can increase the organic content by effective pasture management augmented with manure--no organic matter that can be returned to the soil leaves the farm. Whether you're managing a manure compost pile, spreading composted manure, or simply mowing your fields, minimize mechanical compaction by limiting tractor use, especially when pastures are very wet.

Soil depth on our farm is limited, particularly on hillside pastures where the underlying limestone is close to the surface. This makes management of these areas challenging; wet periods cause groundwater to weep from the surface, creating wet clay soils subject to compaction. During dry periods the grass dies quickly due to shallow root structure. As we divide areas for rotation we separate the most sensitive hillside and allow grazing for a shorter duration. Other parts of the farm where the land is flatter have deep clay--you have to dig three to six feet before encountering rock. Here, planting deep-rooted grass species, adding organic material and soil amendments such as lime, and guarding against soil compaction should leave pastures healthier and more resilient.

Take-Home Message

It is impossible to address every type of pasture management situation in every part of the country. So, evaluate your individual circumstances and take an active role in managing both your horses' health and that of the land.

"Consulting a forage expert through your local county agent would help each individual evaluate and/or modify current forage conditions to help attain desired outcomes," recommends Shine.

About the Author

David Preston

David Preston, president of Preston Construction Group, specializes in unique commercial and equine projects. A horse owner and sportsman, he has built and remodeled several barns in Kentucky and Illinois ranging from development of complete Thoroughbred farms to small horse barns.

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