The Rhizobia bacteria in commercial inoculants are living organisms. They should not be exposed to heat, direct sunlight, excessive moisture, or other adverse conditions, according to USDA Natural Resource Conservation Service Technical Note. Each package should have an expiration date and be used by this date to ensure maximum viability of the bacteria. It is easy to forget the small packages of inoculants contain living organisms and throw them on the dash board of a vehicle or lay them on a hot table top or metal planter lid while getting seed ready to plant. Such conditions can create excessive heat quickly and are detrimental to the Rhizobia in the inoculant. In order to ensure the maximum effectiveness of the inoculant always follow the checklist below:
- Select the proper inoculant for the legume species.
- Check the expiration date on the package before using inoculants to insure they are viable or will still be viable by the expected planting date.
- Always store seed and inoculants in a cool dry place out of direct sun, some brands recommend refrigeration.
- Do not mix inoculants with fertilizers or pesticides during planting, fertilizer salts and chemicals can kill the bacteria.
- Graphite, lime, or other commercial, dry seed lubricants can be used to facilitate seed flow through the planter without harming the Rhizobia.
- Some seed from commercial sources, particularly clovers, comes with a seed treatment which includes the inoculant. Always ask the supplier if the seed is pre-inoculated if the seed appears to be treated or have seed coating applied, and store as you would any inoculant.