For thousands of years gardeners have wondered why planting beans and other legumes improves the soil. Today we know why. The plants are “infected” with a soil bacterium called Rhizobium. This microscopic miracle beefs up garden soil with a shot of all-natural Nitrogen. Here’s how it works, and how you can ensure Rhizobium is in your soil.
When certain legumes – beans, peas, lentils, clover, vetch – are inoculated (read “infected”) with “Rhizobium”, nodules form on the roots. These root nodules are little dynamos converting atmospheric nitrogen, acquired via the leaves, into useable nitrogen that goes into the soil. This marvelous bit of botanical wonderment is called “Nitrogen Fixation”.
Dry Innoculant
Rhizobium is present in most soils; however, years of chemical fertilizers, pesticides, and deep tilling may have caused a Rhizo Shortage. Correcting the problem is easy. You can infect your legumes yourself with commercial inoculants. These inoculants are usually a fine powder and are applied to the legume seed just before planting.
The best way to inoculate legume seeds is the Slurry Method. Inoculant powder is mixed with water or a liquid “sticky” solution (e.g. 10-20% water mixture) to form a watery goo. Seeds are coated with this slurry just before planting.
IMPORTANT POINTS TO REMEMBER WHEN INOCULATING YOUR LEGUMES
– Select an inoculant recommended for the legume you are planting.
– Never use chlorinated water to mix the slurry.
– Plant seeds within 24 hours of inoculation.
– Keep soil moist.
– Buy fresh inoculant each year.
– Inoculate winter legume cover crop seeds such as clover and vetch.
(Some pre-inoculated cover crop seeds are available)
– Never mix inoculants with fertilizers, pesticides, or lime.
– Store inoculants according to manufacture recommendations
– Do not expose inoculants to direct sunlight or high heat.
– Wash hands thoroughly after inoculating seeds.
Commercial Rhizobium inoculants are sold in most nurseries and seed houses. Some are called “Seed Inoculant” or “Soil Inoculant”. One major seed vendor calls their product “Pea and Bean Booster”. Whatever product you choose, Rhizobium will give your garden soil a cheap and natural Nitrogen shot in the arm. And the good news – once the Rhizobium is in your soil it’s there to stay.