Nitrogen is generally the most limiting nutrient for plant growth and it is also one of the most expensive nutrients when purchased as a commercial fertilizer.
Rhizobium bacteria, which live in small nodules on the legume plant’s root system, have the ability to use nitrogen from the air and convert it to ammonia (NH3).
This readily converts to ammonium (NH4) like we find in ammonium nitrate or ammonium sulfate, which plants can use.
Here are a few reasons we should include these plants in pastures and meadows to provide forage for our livestock.
– Less nitrogen fertilizer is needed — Since nitrogen from the atmosphere is fixed in the nodules on the legume roots, less nitrogen needs to be applied to maximize growth.
The amount of nitrogen fixed depends on plant species, stand density, soil fertility, weather, plant health and the amount of leaf surface produced on the legumes.
Studies have shown legumes can fix more than 200 pounds of nitrogen per acre.
– Improved forage quality — Forage quality of legume plants are generally higher than grasses when they are compared at the same stage of maturity.
Legumes are generally higher in crude protein, mineral content and are more readily digested by the grazing animal than are grasses.
Many research studies confirm higher rates of gain where legumes are included in the pasture mix.
– Better distribution of growth — Adding legumes to predominantly grass pastures may increase the amount of time animals can graze a paddock.
Legume plants often fill voids in a grass system and remain productive during summer months when cool season grass pastures are very slow at regrowing.
– Increase forage yields — Total dry matter yield of a mixed grass and legume forage is generally higher than that of straight grass pastures.
The average of a two year study from the University of Kentucky showed increased dry matter production when red clover was grown with fescue vs. fescue grown with nitrogen fertilization.
In that study, zero pounds, 90 pounds and 180 pounds of nitrogen per acre were applied to monoculture fescue. This was compared to a red clover-fescue mixture that had 6 pounds of red clover seed added per acre with the fescue when planted.
Results indicated the mixture of red clover-fescue out produced all the straight fescue plots even where the highest amount of nitrogen was applied.
– Reduce production risk — A mix of grass plants and legumes provide a lower risk of production failure for a farm manager than a pure stand.
Less susceptibility to total production loss by disease, insects or adverse weather conditions is incurred with mixed species forages.
– Reduced animal toxicities — Using legumes to dilute endophyte consumption from fescue pastures is a good practice.
Legumes provide dry matter to reduce the amount of infected grass consumed in fescue pastures. Grass tetany problems may also be reduced if legumes are in the pasture because legumes provide higher levels of magnesium than most grass plants.
– Added benefit in crop rotations — In addition to adding nitrogen for succeeding crops, legumes can improve soil tilth by creating deep root channels that will benefit following crops.
Red clover, in a mixture with other clovers and grasses, result in soils near the surface and lower layers being more fully occupied with roots than they would be by a stand of a monoculture grass.
This increases organic matter in the soil.
– Environmental benefits — Because the legume plants ability to “fix” nitrogen in the soil, legumes provide a natural slow release of nitrogen.
Because of their flowering habit, legumes provide pollen and nectar for honeybees that are beneficial to many crops.
– Aesthetic value — Legumes also provide colorful displays of flowers and diversity to pastures and meadows that may be enjoyed throughout the growing season.
– Increase profit potential — More milk production, higher weaning weights, better average daily gains and improved conception rates for reproductive efficiency are possible when legumes make up a significant portion of the forage mix.
Legume plants are agronomically sound, environmentally friendly and economically advantageous when included in forage crops.
Frost seeding is an easy way to incorporate legumes into pastures, and the time to frost seed in Ohio is close at hand.
Many articles are available to help you in selecting varieties of legume seed, rates of application, seed inoculation needs and field preparation methods to obtain a good stand.
Remember, just adding more seed will not benefit legume production if soil fertility, pH and proper grazing management are not included as part of the overall management plan.