Starting Legumes from Seed: Using Inoculant

What's A Legume, Anyway?

Legumes are all plants in the pea and bean family - in Latin, this group of plants is called Fabaceae (formerly Leguminosae). This family of plants includes crops such as soybeans, beans, peas, chickpeas, alfalfa, lentils, fava beans and peanuts.

What's unusual about legumes is that many of them can host a bacteria in their roots. Because of these little bacteria, called Rhizobia, plants in this family can actually take nitrogen from the air and convert it into a form that plants can use as fertilizer! This is called a "symbiotic relationship," because both the bacteria and the plant benefit from living together.

This is why we advise you to rotate your crops - growing one type of plant one year and a different one the next year. By alternating a crop that removes a lot of nitrogen from the soil, such as corn, with a plant that adds nitrogen to the soil, such as beans, your plants will be healthier and happier. (You can also grow beans and corn together in the same year.)

Inoculants

You may have seen "inoculant" listed in seed catalogues or in nursery supply stores. This black powder is used by some gardeners at planting time when they are planting legumes. The powder contains rhizobia, the bacteria we mentioned above. It is not absolutely necessary to use inoculant when planting, because rhizobia is often present in healthy garden soil already. However, many gardeners do recommend it. I would try it if there is not much organic matter in your soil, or if you have not had good luck growing legumes.

There are specific inoculants for specific legumes, so if you want to try using an inoculant, be sure to read the packaging to make sure that you are using just the right one for your crop.

To use inoculant, simply follow the package directions. Typically, the inoculant, which is in a powder form, is mixed with the seeds at planting time, and then the seeds are planted directly in the ground as usual.

Sources

1. Conley, Shawn P. and Ellsworth Christmas. Using Inoculants in a Corn-Soybean Rotation. Purdue University Extension 2005. http://www.ces.purdue.edu/extmedia/SPS/SPS-100-W.pdf