10. Grass for Nonlactating Cows
Potassium (K) concentration in perennial grass forages is considerably more important than nitrogen (N) or crude protein (CP) content, when used as dry cow forage. Relatively low K concentration in non-lactating dairy cow diets is critical to animal health. Species selection, fertilization, harvest management, and time of season can all impact the K concentration of grass forage [GIS-25]. Perennial grasses are luxury consumers of K, resulting in high K forages grown on fields with excess soil K due to repeated animal manure applications. The goal of a K management program for perennial cool-season grasses for non-lactating dairy cow forage is to provide sufficient K for plant functions without accumulating excess plant K.
It is possible to achieve sufficiently low forage K concentrations for non-lactating dairy cow forage in cool-season grasses and maintain stand persistence. We conducted perennial grass experiments at several sites in New York state investigating proper grass species and cultivar selection, cutting management, as well as N and manure management necessary to produce an adequate supply of low K grass for dry cows.
Mature grass on soil low K availability will likely produce forage with low K content.