Pasture seedings may be established using conventional or no-till techniques. These procedures are identical to those described for establishing forages for hay or silage. Since pastures often are established on sloping land, proper attention must be paid to erosion control measures.
Over time, legumes and productive or palatable grasses may be lost from pasture because of overgrazing or diseases and pests. Renovation techniques can restore these stands to a high level of production without destroying the existing sod. There are three forms of renovation for such sites: limited tillage, no-tillage with chemical sod control, and no-tillage with animal grazing for sod control. All methods for introducing grasses or legumes into existing sods depend on adequate fertility and proper pH. Soil samples should be taken a year ahead of renovation and any deficiencies should be corrected.
This method uses a disk or other tillage implement to disturb the sod surface. Sod should be tilled once or twice to destroy 30 to 50 percent of the surface and expose the soil. Seed should be broadcast on or drilled into the pastures in late winter or early spring. Pastures should be mowed, grazed, or treated with an appropriate herbicide to prevent excessive competition from surviving pasture plants or weeds.
No-Tillage with Chemical Sod Control
This technique uses herbicides to suppress sod growth and allow establishment of introduced species. If possible, the pasture to be renovated should be grazed closely the preceding fall to depress spring growth vigor. If biennial or perennial broadleaf weeds are present, the pasture should be sprayed the previous autumn with 2,4-D or Banvel. In spring, the sod should be sprayed with Gramoxone Inteon when 2 to 3 inches of new growth are present. Special no-till drills, designed to cut a slit in the sod for seed placement, have been successful. Seedings in May or later, particularly of alfalfa, have benefited from an insecticide at planting.
No Tillage with Grazing for Sod Competition Control
This technique succeeds best where the sod is open and not a dense cover, a condition promoted by heavy grazing the previous fall. Red clover is one of the easiest species to establish using this technique. Seed may be sown in late February through early April while the soil surface is still freezing and thawing. When the existing sod has 2 to 4 inches of new growth in spring, it should be grazed closely (1½ inches) for a short period (1 week or less). Then, when regrowth is 6 to 8 inches, the sod should be grazed closely again (3 inches). The pasture should be mowed at the early boot stage to remove tall stemmy regrowth. The pasture then can be rotationally grazed through the summer.
Frost seeding is a common method of introducing desirable species into an existing pasture. The technique involves spreading the seeds onto the pasture in late winter when the ground is frozen at night and thaws during the day. Freezing and thawing creates openings (honeycombs) in the soil surface into which seeds fall. If adequate seed-soil contact exists, germination occurs when the soil warms.
Frost seeding has proven most successful with clovers. The ground must be frozen when the seeds are spread. For this reason, frost seeding generally is done in the early morning before the temperature warms and the soil begins to thaw.