1. Get a soil test. These can be done inexpensively, sometimes free, at agriculture extension services. If you have an agricultural college nearby, see if students are interested in doing the soil test for the experience as a lab.
2. Research what grasses to plant to make maximum nutrition, not just grass. Do you want to seed in a percentage of clover or alfalfa? Are you even sure what is out there now? Not all grass - or pasture - is created equal. A *good* pasture can provide nutrition, just grass provides mostly bulk. Keep in mind if you put in legumes it can also boost soil.
3. Depending on the results of the soil test, fertilize! Keep the horses off of it, according to directions on the fertilizer. But use a good fertilizer, lime or whatever else the test shows your soil needs to grow the best pasture possible.
4. If there's noxious weeds eliminate them! Go through your pastures and really look. If you need to use an herbacide to get rid of weeds, block off the field according to directions.
5. Mow regularly your pastures. If they're grown up consider mowing and baling it. If you watch horses they'll make some inroads to the tall stuff, nibbling here and there, but most of what they eat is knee to ankle high. If they're overgrazing in spots look closely what's there that they're liking. Regularly mowing the pastures - even two or three times over the growing season - keeps the pasture coming on fresh and more palatible.
6. Drag pastures regularly. Consider using a drag once a month on the pastures to break up piles of manure. Breaking these up can help eliminate 'contaminated' areas where horses are less likely to eat, and allows the manure to break down as fertilizer easier.
7. Rotate pastures. Don't let them get overgrazed. Watch for areas that create ditches or other possible hazards - install drainage and level it out. This isn't cheap, but preserves your pasture and helps prevent injuries while the horse is turned out.
8. Don't turn horses on pasture in bad weather. If it's frozen or raining consider having paddocks available instead of using the pasture. Shoes and even barefoot hooves can tear up the root systems of grasses, leave damaged spots and worn areas of mud in horses favorite spots. Horses with caulks on the shoes can also do damage to the ground.
9. Have a quality mineral available for horses on pasture - a good quality mineral can help the horse make use of the pasture they're eating more efficiently.
10. Maintain fences to keep horses in. While this might not seem direct to pastures, deer and wildlife can jump a fence, or try to, and create damage. Walking your fences on a regular basis can catch problems before a horse gets loose or hurt.
If you're fortunate enough to have a space to have a pasture, even if just an acre or two, *use* it! The horses can use the nutrition, it's less that you have to mow and maintain and it gives horses valued outdoor time in good weather. Keep a water tub in the corner of the field, near the gate, and clean it at least weekly to maintain drinkable water. If you don't want to get a metal one get a couple larger inexpensive "muck buckets", secure to the fence and fill with water. The important thing is to have clean water available.
Good quality pasture is an asset. For a couple hours a day it lets a horse be just a horse, something that makes a mental difference whether he's a three day event horse, a reining competitor or just a pleasure horse. Since youre turning him out anyway, use the time for an added benefit of nutrition. It keeps the horse happy, eliminates they hay you have to buy, makes better use of your facility and leaves a viable forage you have more control over than that which comes in bales or bags.
During winter weather keep a 'dry' paddock for turnout of horses. Protect pastures by keeping horses off of them during freezing or muddy conditions. Photo courtesy Grey Horse Farm, IL