Although we like to think of pastures as monocultures, as stands mature, they become a complex mixture of plants that are adapted to the region, soil type, and management regime. So, the question becomes do we fight mother nature and try to establish and maintain pure stands or do we work to optimize the management of these complex mixtures to better meet our needs? Here are a few ways we can optimize management of forage resources already existing on our farms.
Liming pastures – In a mixed sward, adding lime to a soil with a low pH would tend encourage the clover. If we did not add lime, we might expect grasses and acid tolerant legume species to be present in greater quantities. Lime also makes other nutrients in the soil more available to the plant. If pastures need lime as indicated by a soil test, then lime should be the first thing applied.
Fertilizing pastures – Improved grasses and legumes need good soil fertility to persist and be productive. If soil fertility is low it will favor species that are more efficient at extracting and using nutrients from the soil.
Nitrogen – Application rate and timing can also be used to shift the botanical composition of pastures. Nitrogen fertilization will tend to encourage grass growth shifting the composition toward grasses and away from legumes. Early spring and late summer applications will encourage cool-season grass growth. In contrast, late spring and summer applications will shift the pasture composition toward crabgrass and bermudagrass in mixed stands.
Grazing management and forage plant growth – After defoliation (grazing or cutting), plants need energy to regrow. In grasses this energy comes from two places. The first is leaf area remaining after grazing. The remaining leaf area is like a solar panel that captures sunlight and converts it into energy (sugars and carbohydrates) that the plant can use for regrowth. The more leaf area we leave, the larger the solar panel and the faster pastures will regrow. The second place that energy comes from for regrowth, is stored carbohydrates. The location of these stored energy reserves depends on the plant species. Grasses that store their energy in the stem base are less tolerant to close and frequent grazing compared with grasses that store their energy in stolons and rhizomes that are safely below the grazing height of livestock. Resting pastures allows leaf area to regrow and carbohydrate reserves to be stored up.
Grazing height – In our naturalized pastures, close grazing will tend to favor grass and legume species that have leaf area and energy stores close to the soil surface. Close grazing results in a shift toward low growing species such as bermudagrass, Kentucky bluegrass, and white clover. A higher grazing height would tend to shift the botanical composition back toward our tall growing cool-season grass species such as tall fescue and orchardgrass.
Grazing frequency – Some species are more tolerant of frequent grazing. These species tend to have leaf area close to the soil surface that is retained even under close grazing and include bluegrass, white clover, and bermudagrass. This means that grazing naturalized pastures closely and frequently will tend to shift the botanical composition toward these species.
Grazing timing – Grazing a mixture that includes both cool- and warm-season species during the summer months will tend to shift the botanical composition toward the warm-season species, especially during and after droughts.
Using improved varieties – These varieties may offer considerable benefits in terms of improved yield, animal performance, and persistence.
In most cases, working with nature greatly improves the chances of success. Grazing is no different. Successful grazing systems are based on forage species that are well adapted to local conditions and managing those species to meet specific needs. ~ Dr. Chris Teutsch, for Cow Country News.