Fall Forage Management

By Stephanie Karhoff and Kyle Verhoff

Fall provides a great opportunity to scout and manage forage hay fields and pastures. In established stands, final harvest or intensive grazing should already have taken place to allow a fall rest period, except if planning to frost seed legumes. If needed, there is still time to soil sample and address winter annual weed concerns.

Soil test fields that will be seeded to forages next year. Apply lime as needed to adjust pH levels. Maintaining proper soil pH increases nutrient availability and will strengthen forage stands, decreasing their susceptibility to stresses like insects, diseases, or weed infestations. The 2020 Tri-State Field Crop Fertilizer Recommendations for Corn, Soybean, Wheat, and Alfalfa (Extension Bulletin 974) recommends consistently soil sampling every 3 to 4 years at no more than 25-acre samples. Lime applications are recommended when soil pH is two to three units below the desired level. In mineral soils (less than 20% organic matter) where the subsoil pH is less than 6.0, the target pH is 6.8 for alfalfa and other forage legumes. In western Ohio, or in general, where the subsoil pH is greater than 6.0, the target pH is 6.5 for alfalfa and 6.0 for other forage legumes.

Now is also the time to scout for troublesome weeds like cressleaf groundsel, poison hemlock, wild carrot, dandelion, and Canada thistle in your hay fields. Fall herbicide applications are the most effective management tool against these species. That is because winter annuals like cressleaf groundsel are at the beginning of their life cycle and more vulnerable to herbicides. Control of biennials like poison hemlock and wild carrot, and perennials like dandelion and Canada thistle, is also improved since systemic herbicides will be moved to root systems along with nutrients.

Managing these weeds now is especially important in fields recently seeded this summer or early fall. Your fall herbicide options include 2,4-DB (Butyrac), Pursuit, Raptor, and clethodim in newly established pure alfalfa stands. Velpar or a dormant application of metribuzin are both options for established stands. Grass hay and pastures have a wider range of options found in the “Permanent Grass Pastures/CRP/Grass Hay” section of the Ohio, Indiana, and Illinois Weed Control Guide (Extension Bulletin 789).

With winter approaching, producers looking to extend grazing need to be aware of a few key concerns. One concern is forage toxicity. Like some previously mentioned weeds, forages like grain sorghum and sorghum-sudangrass hybrids have a high prussic acid poisoning potential. With that in mind, harvest or the final grazing of pastures with summer annuals should occur before the first frost. That first frost is also important if you are grazing high concentrations of forage legumes is a second concern. Grazing a high concentration of forage legumes a day or two after a hard frost increases the risk of bloat, so it is best to wait a few days and supplement with dry hay.

For producers that are grazing stockpiled pastures this winter, now is the time to take samples from hay and silage to calculate the nutritive value of your winter feed and to inform any supplementation needs. While grazing stockpiled forages, leaving a forage residual of four inches and having a plan to protect the pasture from livestock damage following significant precipitation events are vital to the long-term health and production of the pasture.