You’ve made your crop rotation decisions for the year and have pulled out the equipment to work on in preparation for seeding. Shortly you’ll be making a trip to your retailer to pick up some of the crop protection and other input products you’ll need early on in the growing season. One of those products you’ll pickup is a little different from the others. Can you remember which one? It’s your inoculant. It’s different in that it contains living organisms called rhizobia that will provide nitrogen in a usable form to the plant. Rhizobia need to be in a living state to work, so they require proper storage conditions to maintain those healthy and viable populations.
Rhizobial numbers will not increase after being put into commercial packaging. Everyone involved in the supply chain process along with you the grower can play a role in helping to preserve viable populations of rhizobia in inoculant products.
So what can you do as a producer to help keep the rhizobia alive? When you get the inoculant back to your farm prior to planting, make sure to store it in a cool dry location. In general, any formulation of inoculant whether it be peat, liquid or granular should be stored below 15°C. Every effort should be made to minimize temperature fluctuations during storage.
If you are storing a liquid inoculant product, store it as cool as you possibly can, WITHOUT allowing it to freeze (2-4oC is ideal). This is critical for liquid inoculants in particular.
Granular inoculants should be stored flat on a pallet (ideally stored at 8-12oC). This will avoid direct contact with the floor as it may be cold and damp. Be mindful not to store granules too close to direct heat sources in a storage building as it may cause moisture migration within the bag.
Peat formulations are generally the most durable in terms of storage. Ideal storage conditions for peat formulations are 0-5oC, although they can tolerate sub-zero storage conditions.
Liquid Extender that is sold in conjunction with liquid soybean inoculants (HiStick® N/T Liquid or Nodulator® N/T Liquid) does not contain any rhizobia, however proper storage conditions should also be maintained to ensure product performance. Keep Liquid Extender from freezing and avoid storing at high temperatures.
Whether you are picking up seed inoculated by your retailer or inoculating seed on farm yourself many of the same principles apply to keeping the inoculant on the seed viable. Once seed is inoculated, exposure to temperatures, direct sunlight and drying winds are the most important factors to control for safe storage. Make sure to tarp your load of seed after it is inoculated or park your gravity wagon under the shade of a tree. Even better yet, plant seed as soon as possible after inoculating in order to benefit from the highest number of rhizobia that you possibly can. Once the seed is in the soil, it is in the best micro habitat to preserve rhizobial numbers.
If you can control exposure to temperatures and UV and plant your seed as soon as possible after inoculation, you’ll be well on your way to help preserve the full value of your purchased inoculants.