The spring condition of our perennial forages is strongly influenced by the weather and management they received last year. Given how dry our last two summers have been, many pastures appear thinner than normal going into spring. Below are some recommendations for identifying and managing thin stands.
Determine whether your pasture has sufficient plant density. In newly planted pastures, we recommend 20-25 seedlings per square foot. The optimal plant density varies a lot more in established fields. For alfalfa, sustained yield in fields over 3 years old is possible when there are >55 stems per square foot. Estimating plant cover is more realistic than counting stems or plants in diverse pasture mixes; the NRCS Pasture Condition Scoring guidelines for our area recommend 80+% of ground be covered by growing or dormant plants, with impairments being identified when >40% of soil is bare. The density grid on a grazing stick can also be utilized to identify thin pastures.
Adjust your grazing management for thin stands. Thin stands will have less forage available for livestock, so a mix of adjusting stocking rates and supplementing with hay or other feeds is necessary to reduce the risk of overgrazing.
Pasture stands can be augmented with overseeding. If stands are thin and you can see more than 50% of the soil surface, suppressing existing plants with herbicides may not be necessary. No-till drills will allow for better seed-soil contact than broadcast seedings, but both are options in our area. Increase seeding rates by at least 10% when using broadcast methods. Calibration for no-till drills can greatly improve accuracy and reduce the risk of planting too little seed or planting too deep. Most cool-season perennials in Ohio should be planted in April; waiting til May can greatly reduce seedling survival when summer weather heats up. Â Â Â Â Â Â Â
Fertility is critical for grass growth, but adding potassium at this time of year can increase risk of grass tetany. Grass tetany occurs when grasses take up luxury potassium, leading to an imbalance of potassium and magnesium in lush spring growth. We generally recommend folks avoid applying potassium between green-up and early June (site-specific exceptions to this rule are based on very low soil test K results and will require split applications of potash).
Thin pastures are more prone to weed management challenges. Before applying any herbicides check the Weed Control Guide and the product label and pay close attention to livestock related restrictions on many herbicides. Several products include grazing intervals, and these often differ for lactating and non‑lactating animals. Some herbicides also require a waiting period before animals can be marketed, due to slaughter withdrawal intervals tied to treated forage.
Another important consideration is that certain herbicides can leave residues in hay or be carried through manure after livestock consume treated forages. These residues may remain active long enough to injure sensitive crops if hay is moved off‑farm or if manure is applied to fields intended for broadleaf crops, gardens, or new forage seedings.
Checking both the regional weed control guides and each product label before application helps prevent livestock issues, marketing delays, and unintended crop injury from grazing, hay or manure movement.
Other Resources:
Ohio Agronomy Guide: https://extensionpubs.osu.edu/ohio-agronomy-guide-16th-edition-pdf/
Using a Grazing Stick: https://u.osu.edu/sheep/2024/04/23/use-a-grazing-stick-to-measure-forages/
Pasture Renovation Factsheet: https://ohioline.osu.edu/factsheet/anr-0159
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