Why Do We Want Legumes in Our Pastures?

Forage legumes are plants that are in the pea family (Fabaceae) and include alfalfa, clovers, vetches and trefoils. We like them because they help take nitrogen out of the atmosphere and fix it in our soils. They are a tool we can use to increase fertility and forage production without the addition of man-made fertilizers. Legumes' nitrogen fixing super-power is really a result of bacteria that legumes host in their roots. These bacteria, known as rhizobia, invade the root and multiply forming a root nodule. The rhizobia get all the nutrients they need from the plant, and in return the rhizobia draw nitrogen from the air and convert it to a form of nitrogen that the host plant can use. It's a mutually beneficial, symbiotic relationship. When the nodules are young and haven't started fixing nitrogen yet, they are white or gray inside. Once they're working they will be larger and will gradually turn pink or reddish in color. When they're no longer fixing nitrogen, the nodules turn green and may even be discarded by the plant. Nodules should form on roots 2 to 3 weeks after germination. If