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Overseeding Pastures In Kentucky
DR. RAY SMITH
LEXINGTON, KY.
Forage establishment techniques can vary widely depending upon forage species, location, soil type, pasture situation and intended use. Using good establishment techniques are essential to achieving good, high yielding forage stands. Here are some considerations for forage establishment.
Overseeding vs. Complete Re-Establishment
Pasture quality can be greatly improved by overseeding an existing pasture to thicken stands and improve forage diversity. Overseeding an existing pasture does not remove productive grasses, costs less in herbicides, seed and equipment use and requires less rest between seeding and grazing compared to complete re-establishment. Successful complete re-establishment will result in the greatest improvement of pastures.
Generally speaking, complete re-establishment is recommended when more than 50 percent of the pasture is undesirable. Undesirable plants can include weeds, particularly noxious or difficult to control weeds, low productivity grasses and grasses with anti-quality components, such as KY 31 tall fescue. Re-establishment should only be considered when proper time and resources can be devoted to pasture improvement.
The following 6 points are important to successfully establishing cool season grasses, whether overseeding or complete re-establishment.
1) Soil Fertility
Ensuring proper soil fertility is the key to successful establishment. Apply lime and fertilizers according to soil test recommendations to optimize plant growth and establishment success. Tillage will help to further incorporate soil amendments and reduce runoff.
2) Seed Quality and Variety
High-quality seed has high rates of germination and is free of contaminants. Select a variety that has been proven to be a top performer under your location’s conditions. Some situations will favor high yielding varieties while others will benefit from good seedling vigor, grazing tolerance or winter survival. The University of Kentucky performs forage variety testing for many forages. Results are available http://www.uky.edu/Ag/Forage/ForageVarietyTrials2.htm at
3) Seeding Rate
Seeding more seed than needed will increase the cost of seeding without improving the stand. Low seeding rates will result in thin stands and encourage weed encroachment. When seeding mixtures, be sure that more aggressive forages such as ryegrass are in smaller quantities (10-15 percent) to prevent shading and competition with slower growing perennial forages like tall fescue and orchardgrass.
4) Seeding Method
Forages can be successfully established with a variety of planters and planting techniques. The majority of forages require shallow seed placement (1/4-1/2 inch). Cultipacker-seeders and drills with accurate seed depth adjustment are best for small seeded species. Broadcasting of small seeded species can be successful into a tilled seedbed if a cultipacker is used to cover and firm the surface soil afterwards. Broadcasting followed by light disking is risky and can result in seed covered too deeply. If broadcasting is used, the seeding rate should be increased 15-25 percent to help compensate for seed placed too deep for emergence. For small seeded forage species, the cultipacker-seeder is generally superior to the drill for getting good stands.
5) Control Competition
Attaining adequate weed suppression and/or control is essential to successful forage establishment. Many competitive weeds establish much faster than the planted forage crop. As such, they may rob the desired forage plants of needed soil moisture and sunlight for growth and survival. There should be a weed control plan for every forage planting. In many cases, it will be desirable to apply a pre-emergent or post-emergent herbicide, depending upon the forage/weed species involved. In some situations, adequate weed suppression can be attained by reducing or eliminating starter nitrogen fertilizer, and/or by frequent close mowing.
6) Rest
Grazing newly seeded pastures is another major cause of stand failure. Wait several months (6-8 months is ideal) for the pasture to become well established before grazing. It is recommended to allow enough time for the stand to mature, and then take one hay cutting, or one quick grazing, before adding the pasture back into your grazing system.
Pasture Renovation
There are several methods that do not require tillage for renovation of tough grasses such as tall fescue. One is generally referred to as the spray-smoother-spray method. For example, an old KY 31 fescue stand can be sprayed out in the early spring with one or two applications of glyphosate and then no-till planted with a summer annual crop like pearl millet or sorghum sudangrass. The summer crop is harvested or grazed and the area is sprayed again with glyphosate just prior to replanting a novel endophyte fescue. Another technique is to graze or mow the area to keep KY 31 tall fescue from seeding in the spring. Continue grazing or mowing throughout the summer. Prior to replanting fescue make two successive glyphosate applications at high rates. The first should be 4 to 6 weeks prior planting and the second just prior to planting to kill any fescue that survived the first application. Remember that hay brought into the field that has been renovated may contain seed of toxic fescue. ∆
DR. RAY SMITH: Forage Extension Professor, University of Kentucky
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