Study shows legumes add to pasture value
KEARNEY, Neb. – Producers who interseed existing pastures with legumes can gain in excess of $50 per acre in annual production and savings, said a University of Nebraska-Lincoln specialist.
A five-year study compared smooth brome pasture fertilized with nitrogen to unfertilized pasture interseeded with 15-25 percent legumes, said Bruce Anderson, UNL Forage Specialist.
Legumes improve animal performance by adding protein and rapid digestibility to grass pastures, Anderson said. As the grass gets more mature, more fibrous and less digestible late in the season, the additional protein helps rumen microbes digest the coarse feed more effectively. That results in better nutrition coming from both the legume and the grass. The legumes also tend to be more rapidly digested, so the animal can eat more.
The average daily gain of animals grazing legume pastures was about 0.4 pounds more per day, which translates into about 50 pounds additional gain per head. For a producer, that might be another $25 of animal product coming from each acre of grass.
In addition, by fixing their own nitrogen and sharing it with the grass, legumes save as much as $25 to $30 per acre in fertilizer cost, Anderson said.
To establish legumes into existing grassland, Anderson advised a three-pronged approach:
• Make sure the soil fertility is appropriate for legumes. Legumes need a more neutral soil pH, so producers may need to add lime to acid soils. Legumes need more phosphorus, so phosphorus fertilization at the time of establishment is critical. Producers should avoid using nitrogen the year they establish legumes so they don’t stimulate grass competition.
• Make sure to get the seed into the soil. Anderson prefers using a drill because they provide better placement and distribution of the seed. Broadcasting the seed very early in the spring might allow rainfall and snow, as well as freezing and thawing of the soil to work some seed into the soil.
• Control the competition from existing sod. Anderson advised heavily grazing and even hurting the sod a little bit the year before planting legumes. That can cause the grass to grow a little more slowly in spring. A herbicide like Gramoxone can be sprayed on the new green grass in spring to suppress any further growth for about three weeks. Any time the grass gets tall enough to shade the new seedlings, producers should very quickly graze it off – maybe in a day or two – then move the animals off and allow the seedlings and grass to grow again. That procedure might have to be repeated so the legume seedlings get light all season.
For more about profitable grazing systems in Nebraska, download the program online from http://www.grassland.unl.edu/2009%20Grazing%20Conference%20brochure.pdf .