Now that spring has arrived, some growers have already began seeding while others are just staring at the snow waiting for it all to melt. This means everyone is talking about seeding and a topic in conversation to the legume growers is inoculating. As many of you are preparing for this crucial time, some of you might be wondering “why should I use liquid inoculant or granular inoculant? What’s the difference between them?”. The benefits of bacteria and microorganisms are nothing new when it comes to finding ways to increase your yields, it is a proven practice (1, 2). In this week’s edition of Growing Possibilities, we’ll revisit the topic of inoculation, and focus on the differences between liquid & granular inoculants and highlight some of the key things to consider when choosing your inoculant formulation or type of inoculant to use for your crops.

To begin with, the obvious and basic difference is that granular are solid and liquid are not. Granular inoculants are small granules covered or injected with the desired bacteria or microorganism. While, liquid inoculants are bacteria or microorganisms suspended in a liquid, known as a growing media. Beyond that the application methods of either inoculants are also quite different.

First off, granular inoculants can only be applied to the seed in-furrow, which makes them more likely to cause bridging, depending on the product used. This means that granular inoculants often bunch up and clump/bridge when they are in the hopper of the applicator, which can cause granules to flow out unevenly or stop flowing out entirely, causing inconveniences such as dust being created due to the clashing of the granules. If this problem goes unnoticed and is not corrected as soon as possible, it will cause areas of the field under-inoculated or uninoculated.  Another disadvantage of granular inoculants is that the packages are generally a lot bulkier/heavier so they are harder to lift which can lead to a messier application process. It’s a lot of bags to carry to the field when seeding! However, most granular inoculants come with less compatibility issues with fertilizers and other treatments, as it directly applied in the soil.

On the other hand, liquid inoculants can be applied either in-furrow during the planting process or on the seed surface itself prior to planting. As well, another advantage of liquid inoculants is that they are a lot less likely to cause bridging during the application process, this leads to a more uniform application. In general, liquid inoculants are much easier to handle and a much cleaner process. In fact, if considering on-seed inoculant application, number of retailers do provide pre-inoculated seed to the growers reducing their burden of work. Though liquid inoculants are generally lighter to lift and easier to pour, some company’s products do have a more difficult application process as they come in multiple components that need to be measured and mixed. There are some all in one liquid inoculant, like XiteBio® products that are all in one packaging that makes for a very easy handling, simply dump it into a seed treater or liquid cady and mix in the inoculant thoroughly. As most traditional growers are generally already equipped for granular application, so to switching to liquid in-furrow application may cost them a few bucks as in-furrow liquid application require a different equipment.

Granular inoculants are traditionally more prevalent and proved to be effective, whereas liquid inoculants are much newer in the game although with newer technologically advanced liquid inoculants are as good or better. One aspect that granular does not stand up to liquid is the volume that is required to treat crops. This is because granular inoculants are not as concentrated in terms of bacterial or microbial potency, which means more bags of granular inoculant are needed than liquid inoculant to treat the similar quantity of crops. For example, when treating 800 acres of lentils with a rhizobial inoculant, when it comes to granular inoculants you would need 70 or more bags, compared to treating the same crops with a liquid inoculant like XiteBio® PulseRhizo®, this would only require 5 bags (Fig. 1). So, switching to liquid inoculants from granular can free up some valuable storage space when you are preparing for seeding.  In addition, liquid inoculants are proven to be just as effective, if not more effective than many of the top granular inoculants. On thing you may need to watch is liquid inoculant compatibility with other seed treatment chemicals or starter fertilizers. Although with the advancement with inoculation technology, number good liquid inoculants are compatible with the most popular seed treatment chemicals or starter fertilizers. Hence, most inoculant manufacturers will have compatibility charts like this to show which products their inoculants are compatible with.

So, those are the key differences between liquid and granular inoculant. Which formulation to use depends on factors specific to you and your growing needs. If you do want to try liquid inoculants this seeding season, be sure to check out https://www.xitebio.ca for our products that can be used on a large variety of crops.

 

References

• https://sfamjournals.onlinelibrary.wiley.com/doi/full/10.1111/1751-7915.13517
• https://www.nature.com/scitable/knowledge/library/biological-nitrogen-fixation-23570419/