by Robin Stanback

A perfect storm of weather problems attacked pastures and hay fields from Ohio to Florida last year. Now, the results can be seen throughout the region in shorter spring grasses in pastures, hoof damage and muddy areas in paddocks, and weaker hay fields. Those effects—exacerbated by overabundant rainfall in some regions—most likely will result in a bumper crop of weeds this summer.

"We suffered a triple whammy last year with the late frost at Easter, the drought, and the extreme heat in August," said Roger Allman of the Farm Clinic, an independent research firm in West Lafayette, Indiana. "We didn't have the good growing seasons we normally can depend upon in the spring and in the fall. Pastures really took a beating."

For the past 30 years, Allman has been analyzing soil samples and studying pasture growth on horse farms throughout the world. "Last year was interesting in that, if you looked at the total rainfall for the year, it was within a couple of inches of the 40-year normals," he said. "However, the rain came all at once in the early spring and then again very late in the fall, with little in between.

"The Central Kentucky area got a 'million-dollar' rainfall on the Fourth of July, which really helped the grass, but then that was pretty much it. Georgia got even less."

Lack of rain in the usually damp months of April and May resulted in a very limited spring growing season for pastures. While a late frost complicated the grass problem, it severely impacted hay production. "Hay crops had a major setback when the temperatures dropped to 18 degrees on Easter Sunday last year," said Garry Lacefield, Ph.D, an extension forage specialist and professor of agronomy at the University of Kentucky.

"The hay was only about 18 to 20 inches tall, and that frost killed the terminal buds. Fortunately, alfalfa is a very deep-rooted, resilient plant. The lack of rainfall did not affect it as badly as it did the grasses, but the damage that was done may mean that stands of alfalfa that are usually replaced every four years might need to be replaced sooner."

Severe ragweed

The damage to grasses and hay crops left the door open for opportunistic plants to invade, Allman said. "Weeds will be terrible this year. Ragweed will be very severe. What happened last year is that nobody wanted to mow. The pastures were not growing and the grasses were very dry, so farmers did not run their tractors and mowers over the fields. The plants that were growing were the weeds. They made seed heads, and that seed is poised to germinate this year."

Not all weeds are detrimental (see box at right), but no farmer wants to look across a pasture of broad-leaf weeds and chicory. Early summer is a wonderful time to assess pastures and hay fields to determine problem areas and to develop a plan that will correct them.

At Woodford Feed Co., a Central Kentucky farm supply operation, Debbie Prewitt has been helping farm managers do just that for the past 30 years. "Soil test, soil test, soil test! I cannot stress that enough," Prewitt said. "Any pasture renovation or problem-area plan must start there. If you know what is in the soil, you know what needs to be added to support growth, if adding anything is necessary, and you can develop a plan to follow."

Soil testing can be simple. Most farm supply stores or extension offices have soil probes that can be borrowed. "Farm owners should walk throughout the field or paddock they are testing and collect a number of plugs from different places within that area," Prewitt said.

"As they collect the samples, they should discard the top bits of grass and roots and just put the soil itself in the collection bag. The samples can then be taken to the store or extension office where they can be sent off for testing. We charge $4.50 per test, and I think that is about what the extension office charges as well. This process will provide an overall picture of a particular pasture."

Allman's Farm Clinic goes beyond the type of testing most farms can do on their own, and that is reflected in the price, which is dependent upon the farm's acreage and the amount of testing done. Farm Clinic staff members walk the fields and take an inventory of existing plants, make notes on traffic patterns and bare spots, and look for insect infestations.

Varying conditions

Then they take a number of samples—at least one every two acres—and develop a grid of the pastures that can specifically target problem areas. "Horse pastures are not as uniform a crop as corn or wheat," Allman said. "Horses graze some areas more heavily than others, they damage the ground with their hooves, and then there is the manure. We take all of this into consideration."

Once the testing has been completed, a program can be developed to replenish the soil, treat barren areas, and eliminate weeds. Allman finds many people want to fertilize in the spring, but he said that might not be the best idea.

"Timing is everything when it comes to replenishing the soil," he said. "People fertilizing in the spring should think first about how the grass grows. In the early spring, the grass is high in protein, higher in energy, and low in fiber. If you fertilize then, you increase the protein and energy, and you get problems with founder and colic. Plus, you are feeding growth and not root. It is much better to fertilize in the fall when the energy goes into the root of the plant, making it stronger."

Fall is also the best time to reseed "from fence post to fence post," when the grasses can have the longest possible time from germination to hot, dry weather. "Grasses do much better in winter months than they do in hot, dry months," Allman said.

Still, spot seeding barren areas and protecting them from traffic can be done now. Because there was so little growth in pasture grasses last year, horses ate quite a bit of what was there very low to the ground. The exposed ground then became more vulnerable to erosion and hoof damage, and a prime venue for weed growth.

Lacefield believes spot seeding is a good idea, especially if it can be combined with a rest for that area of the pasture or, ideally, the entire pasture. "If there is any way to give that ground more time to turn brown to green, it should be done," he said.

Prewitt recommends drill seeding, using a shoulder-strap broadcast spreader because it gets the seed into proper contact with the soil. However, she acknowledges that not everyone has access to a drill seeder. "You can use a broadcast spreader and then go over the area with a chain harrow to disturb the ground enough to get the seeds to the soil," Prewitt said. "The bottom line is to get the seed out there."

Chain harrows

Chain harrows also are used to break up clumps of mown grass and manure that can smother the growing grasses beneath them. Prewitt recommends using a chain harrow in the spring, but she advises being very careful about using it in the summer months when it might help to spread weed seeds. Allman believes spreading out the manure is most essential for the health of the paddock.

Grazing management is something most experts agree is essential to helping drought-damaged fields to recover. Rotating horses among different pastures, thus allowing some pastures to rest while others are being grazed, has long been a desirable method of pasture management.  Allman says that is changing. "Years ago, people used to put large groups of horses out together, but today I am seeing much less of that," Allman said. "Rather than a field with 16 yearlings running in it, I see two fields of eight. Neither field is getting a break."

Mowing at the appropriate times and heights is also extremely important. Allman suggests that pastures should be mowed about every 14 days at a height of six to eight inches during rapid spring growth. This keeps the grasses growing leaf rather than concentrating efforts toward seed production. Mowing also helps to control weed propagation. Even in the summer months when the grasses typically are growing more slowly, weeds can produce seed heads that need to be cut off before they mature.

Finally, even the most carefully managed pastures and hay fields will have problems with weed growth from time to time. Nimblewill, a shallow-rooted, ground-covering weed, has an ability to spread like wildfire through a pasture. Although rich in nutrients, nimblewill is unpalatable to horses. Ragweed is a summer annual that can grow to great heights if left uncut. It offers little more to horses than an opportunity for injury if the animals should come in contact with the woody stubble as they graze more nutritious pasture.

And then there is thistle. Both biennial and Canada thistles are insidious, rapid-growing, easily propagated, and difficult to control. "Even with the price of fuel going up as it has been, mowing correctly is the best first defense," Allman said. "When you have to use herbicides, Redeem, Crossbow, and Forefront work well. Most herbicides do a very good job if used correctly. Look at the weeds you are targeting, find the best herbicide for those specific weeds, and follow the directions."

Seeding, chain harrowing, mowing, and weed control all help to produce better pastures and hay fields, but every expert agreed the secret to providing the best forage for horses lies in the soil itself. "The soil is like a bank account from which plants and animals draw necessary nutrients," Allman said. "From time to time, that account needs to be monitored and, if necessary, replenished. Any pasture management program needs to start with a soil test. Doing that in spring and early summer will give a farm manager the time to formulate good management practices that will include livestock rotation, weed control, and fertilization."

Robin Stanback is a Kentucky-based freelance writer