So far, we have observed both expected and unexpected changes. First the nonedible (poisonous when eaten) Sweet Peas, Lathyrus odoratus, from last year surprised us by self-seeding or volunteering. Besides their fragrant and lovely blossoms, Sweet Peas are nitrogen fixers. Most living things need nitrogen to live. There is an abundance of nitrogen in the air, but most living things are unable to use it in that form. Plants get their nitrogen through the soil. We get nitrogen from eating plants. That means that nitrogen must get into the soil to be used by the plants and then by us. Some plants such as those in the legume genus, like beans, peanuts, peas, alfalfa, and clover are nitrogen fixers. This means that these plants provide shelter, in the form of root nodules for the nitrogen-producing bacteria that are in the soil to live in. Some of these nitrogen-fixing plants are intentionally planted by farmers to enrich their soil. These plants are plowed under leaving the roots and stored nitrogen in the soil.
Nodules that bacteria live in.