Horses need high quality forage, says Chad Hall, a forage specialist with DLF International—a Danish co-op of 5,000 seed growers specializing in cool season grasses and clovers. Chad likes to see ryegrass, orchard grass, timothy, fescue, bluegrass, and white clover. White clover is more persistent than red and, seeded 3 to 4 pounds per acre can fix up to 150 units of nitrogen per year.
Chad's cool season grass growth curve is familiar to farmers: spring flush, summer slump, autumn rebound. After the May/June explosion, seed heads signal the grass that growth is done. Clipping can cause regrowth until the weather gets so hot the plants go dormant. One way to even out pasture production is to make hay during the spring flush and feed it during the summer slump.
Chad suggests using small paddocks and moving horses often, perhaps every five days. Horses are pattern grazers and will graze the same area over and over, right down to the bare ground if you let them.
Perennial ryegrass and Kentucky bluegrass have the best grazing tolerance: graze them down to 2" to 3", then graze after 6" to 8" regrowth. With orchard grass, timothy, fescue, and festulolium (a ryegrass and meadow fescue hybrid), graze down to 4", then graze after 8" to 12" of regrowth.
"If it's hot, leave more residue so you don't bake the soil," Chad warns. Alfalfa and, to a lesser extent, clover has energy reserves in its big tap root. By contrast, grasses have their energy reserves in the bottom of the stem, so don't overgraze or clip too short.
"Grazed plants form new leaves from root reserves after about seven days," Chad explains. "Grazing these leaves weakens the plant." After this seven days, the plant can start fueling its growth through photosynthesis, and grazing is safe once again. For winter grazing in October, November, and December Chad recommends fescue because it "maintains quality better and stands up better in the snow."
"Treat grass like a crop, like 200-bushel corn," he says. "Frequent small meals applies to plants." Penn State recommends 50 pounds of nitrogen per ton of forage, and more for intensive grazing. Timing is everything. Apply nitrogen after each harvest, maybe after every other intensive grazing. Phosphorus is especially important in the fall. Early spring may be the least effective time to fertilize.
For renovating pastures, fall seeding is preferable because:
most weeds need warm temperatures to grow, so weed pressure is less;
fall rains may be more dependable;
fall seeding allows for maximum pasture use during spring and summer.
Aggressive varieties like ryegrass and festulolium are suitable for overseeding. Before overseeding, closely graze a live pasture. Clear away any dead brush or debris. Less aggressive varieties such as orchard grass, fescue, and bluegrass are better suited to prepared seedbeds.
Talk with your local Extension agents and seed dealers to see what's best suited for your area, Chad advises. Do a little homework and don't just settle for "whatever is at the store."