Grazing in Michiana
"What is the real problem?" This is how I have boiled down my experiences when answering questions from my years in Extension. I don't wish that statement to sound harsh, but when someone brings me in an unknown bug or plant specimen that I have never seen before, I try to find out why they are concerned before I launch into an answer. One classic concern often is that people think they need a soil test because their crop died. Standard soil testing will tell you about nutrients, not disease or insects. Rarely does a nutrient deficiency cause crop death.
When it comes to horses the two highly suspicious questions are, "How do I renovate my pasture and how do I control weeds?" Most of the time the solution turns out not to be spraying chemicals or seeding issues but overgrazing management.
A thousand-pound horse will need a minimum of two acres for grazing and even then, that may be inadequate, depending on the weather, forage species and soil type. Even if it is a larger area, the horse may find its favorite grazing spot and return to it continually eating it to the ground.
The weed question is usually a good tip-off to overgrazing. A question recently was, "How do I control buckhorn in my pasture?" I could respond to that question with all the chemical solutions we can use that will kill this perennial weed, such as 2,4-D and dicamba. But this low growing, spread-out plant loves the sunlight it gets from low grazing where it does not have to compete with tall plants. It is a classic sign of too many animals on too few acres. I can kill the plant with herbicides, but some of its seed will be there germinating in that same spot for a return engagement. So, that will not solve the weed problem. In reality, I may never be able to undo the existing grazing circumstances.
If you are going to maintain too many animals on too few acres it is no longer a pasture but a lot. Any farm may need a lot area. I have an area on my farm where the cattle come up to water. There is not enough grass, so they graze it continuously into the ground. I need to reduce the area until it is small enough to do the job without turning it into a mud lot. In my area the cows will stop and continuously graze the tender luscious growth on those plants. It drives me up the wall because I know that cows will only take a certain number of bites per day and quit.
Some numbers I have seen are about one bite per second and will take 30,000 bites per day regardless of the amount of forage consumed per bite. They are choosing to reduce their total consumption to get the best tasting intake.
In natural settings, horses graze 16-19 hours per day and also take 30,000 bites. Horses are slower eaters than cattle, who take their daily bites in about eight to 10 hours.
Additionally, the parasitic worm population in those short grass-bites is tremendous and if you have a horse on a course soil, sand colic is a real possibility. So, think about creating a true no-plant dry lot out of part of the area and the rest could be fenced into a separate pasture where animals could be rotated into, allowed to graze and then be removed to let the forage replenish itself.
If you do not want a dry lot but are going to maintain horses on an overgrazed area, then I would suggest bluegrass as your forage. It will not produce more tonnage, but it will stay together and grow as a sod under the horse hooves.
A real horse pasture where animals are rotated in and out would consist of a grass and a legume. Alfalfa is my choice of a legume at seeding. Eventually the stand will decrease due to overgrazing and inherent diseases the plant gets. Clovers can be added back into seeding mixtures to replace the alfalfa. Red clover is the best, but some object to a condition called slobbers. According to the University of Kentucky, "Slobbers often result from horses ingesting the compound slaframine, produced by the Rhizoctoniafungus found on legumes such as red and white clover and alfalfa. For the vast majority of cases, slobbers are no more than a nuisance to horse owners."
With grasses you have more choices. Mine is orchardgrass with timothy a far second. Neither of these two should be allowed to be grazed into the ground continuously. If that is the case then bluegrass, yielding half as much, is your choice for a persistent grass.
Any animal will continually overgraze if given the chance, it's up to you, "the management," to correct the issue.