Pelleting your legume seed before planting may significantly boost the harvest. Legume seed coated with pellets of scientifically selected nitrogen-fixing bacteria will consistently outperform uninoculated seed. Some gardeners report yield increases of up to 25 percent following the application of inoculants.
Garden inoculants, which are available at your local seed store or by mail from gardening magazines, come in an easy-to-use powder form. A 1 1/2-ounce package should cost less than $1 and is enough to coat more than five pounds of seed.
Although most states have laws to regulate the quality of inoculants, three precautions are required in order to insure proper inoculation.
The most important is making sure you buy inoculants that are compatible with the seed to be pelleted. Check the culture expiration data; then store the inoculant in a cool, dry place until you are ready to use it.
Of the three types of exterior coating used for pelleting -- rock phosphate, ground limestone, and lime -- rock phosphate is recommended. Be careful when using lime since some acid-loving bacteria find the alkaline powder toxic.
A binding agent is required for holding the seed pill together. Gum arabic is the most popular with large-scale pelleting operations, but on small gardens I have found that replacing the glue with molasses or corn syrup will aid legume nodulation.
Not only do the complex sugars in these syrups provide extra energy for the bacteria, but the seed halves will not stick together during germination.
Equipment requirements for small-scale pelleting are few. You will need two buckets, one with a tight-fitting lid. I use a 2-quart Tupperware container because the clear plastic allows me to watch the progress of my pellets. For larger batches a 5-gallon bucket with snap-on lid works well.
A stirring stick, 300-mesh screen, and some method of sterilization for your equipment are the only other tools required.
Sterilization is important between batches to prevent cross-contamination. Bacteria selected for use on alfalfa and sweet clover will not nodulate peas, beans, or soybeans.
I try to do my pelleting and planting on overcast days, especially those with rain in the forecast. Prepared seeds grow best when planted just before a rain. Clouds also help to protect the inoculants from the harmful effects of sunlight. Just in case my weather eye is not up to par on planting day, I soak the seeds overnight so as to enhance germination and to give the bacteria a little extra moisture.
Although there is no substitute for experience when pelleting, the following method will produce excellent results. By the second or third try you should be able to pelletize each batch of seed in less than 10 minutes.
Mix water and molasses in a bucket without a lid, according to the instructions on the inoculant package, or until a runny paste is obtained. Molasses should be substituted for about half of the total liquid requirement. Pour the inoculant into the solution and mix thoroughly.
Stir the seed into this mixture a little at a time so that the seed gets evenly coated without becoming a soggy mass.
Scrape the seed off the stock and sides of the bucket occasionally so as to keep the mix uniform.
Measure enough powdered rock phosphate, ground limestone, or lime to equal one-fourth dry seed weight. Sift the powder through the screen into the bucket with a lid.
Scoop the wet seed into the dry container, snap on the lid, and roll or tumble the container back and forth. I open the bucket to break up any clods that form and to add powder when necessary.
Pelleted seed should be planted immediately for the best results, but if you plan on using a seed box the pellets should be dried before use. Spread the pellets on a tarpaulin in the shade for an hour or two to dry. The pellets will be ready to plant when they do not crumble while being rolled lightly betwe en your palms.
Spend a little time pelleting your legume seed this spring: then step back and watch them grow.