May 2024
Source: XiteBio
Is an inoculant different from a biological? Yes and No, and it Depends. Every inoculant needs to contain something that is alive while every biological only needs to contain something that was once alive. Because of this every inoculant can be a biological but not every biological can be an inoculant. One way of looking at it is that inoculants contain live bacteria (or fungi or algae) while biologicals only need to be derived from living sources. Please note this blog pertains to inoculants and biologicals as used in agriculture.
In this week’s edition of Growing Possibilities, we will attempt to explain how, in our opinion, inoculants differ from biologicals in agriculture. Biologicals is a term that currently lacks a standard industry definition. What follows is our best attempt to put a definition to this term, but we do not claim it is the only definition. Biologicals in agriculture or ag-biologicals is a blanket term for any therapeutic substance derived from living sources (1). Ag-biologicals can be applied to a plant to either promote growth (bio fertility) or resist diseases (bio control).
Most people know inoculants from their use on legume crops like soybeans or pulses. The first commercial inoculant was patented in the United States in 1896 (2). Over the course of the 20th century inoculant technology improved to the elite strains and sterile formulations sold today. Soybean and Pulse Inoculants are often products containing live Rhizobium bacteria. “Inoculation is the process of introducing the appropriate Rhizobium bacteria to the soil in numbers sufficient to ensure successful nodulation (3).” An example of these would be XiteBio® SoyRhizo® nitrogen fixing inoculant for soybeans and XiteBio® PulseRhizo® nitrogen fixing inoculant for peas, lentils and faba beans (4).
Ag-biologicals are a little different. With one of the main differences being that the term ag-biologicals often seems to be used to refer to products that can be applied on many different crops like oilseeds, cereals, tuber crops and vegetables, not just on legumes like traditional inoculants. Most ag-biologicals could fit into one of the categories below:
- Microbial (live bacterial or fungal or algal)
- Mycorrhizal (root fungal association)
- PGR (plant growth regulator)
- Adjuvants
Microbial Ag-biologicals are technically inoculants (by the definition we have laid out here) because they contain living microorganisms. XiteBio manufactures only live bacteria based ag-biologicals because of their superior ability to establish and propagate in the soil. Because of the number of bacteria that naturally exist in the soil microbiome the successful introduction and establishment of an ag-biological is easier to achieve with bacteria than with for example a fungus (more on this later).
Mycorrhizal ag-biologicals contain a living fungus and therefore can also be called inoculants. There are far less mycorrhizal fungi naturally present in the soil. This lack of diversity has been shown to make it harder to introduce new mycorrhizal ag-biologicals into agricultural soils. On top of this plants must be mycotrophic (can be colonized by mycorrhiza) to be impacted by mycorrhizal products. Canola for example is not a mycotrophic plant so mycorrhizal inoculants cannot be used on canola. Introduced mycorrhiza can also be outcompeted by existing arbuscular mycorrhizal fungi. In addition, many mycorrhizal ag-biologicals can be sensitive to conditions that exist in agricultural soils like high phosphorus levels that can impede their growth. This does not make them ideal for use in agricultural systems (5).
Plant growth regulators (PGRs) are organic compounds, other than nutrients, that regulate the growth of plants by modifying hormonal action (6, 7). The PGR’s can be natural or synthetic. PGRs derived from natural sources are often referred to as biologicals. They should not be called inoculants.
Biological adjuvants can refer to anything that was derived from living sources and that functions to increase fertility. Many of the biological adjuvant products we have seen on the market are derived from kelp or seaweed and function as biofertilizers. They should not be called inoculants.
An example of a proven and tested microbial ag-biological is the XiteBio® Yield+ line of products, namely: XiteBio® Yield+, XiteBio® Vegi+ and, XiteBio® Tuber+. These products contain a live bacteria called Bacillus firmus. XiteBio has patented a specific strain of this bacteria that is an effective Plant Growth Promoting Rhizobacteria (PGPR). This PGPR stimulates root growth and solubilizes phosphorus helping the plant to grow and access nutrients in the soil. Bacillus firmus bacteria can work across a wide range of crops. The XiteBio® Yield+ line of products is compatible with many crops including oilseeds (e.g., canola, mustard), cereals (e.g., corn, wheat), legumes (e.g., soybeans, lentils), vegetables (e.g., tomatoes, cucumbers) and tuber crops (e.g., potatoes, sugar beets) etc.
So, is an inoculant different from a biological? Well yes and no, and it depends. XiteBio’s products are all bacteria based and so qualify as both inoculants and ag-biologicals. We hope that this blog has added to the conversation around what exactly qualifies as an inoculant or ag-biological. To learn more about our inoculant and ag-biological products please contact one of our sales reps by visiting our contact page. Whatever you call your biological crop inputs we wish you healthier plants and better yields.
- Biological; Oxford English Dictionary, Google
- https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6925611/
- https://www.saskatchewan.ca/business/agriculture-natural-resources-and-industry/agribusiness-farmers-and-ranchers/crops-and-irrigation/soils-fertility-and-nutrients/inoculation-of-pulse-crops
- https://xitebio.ca/inoculant-and-biological-faqs/#n-fixing-inoculants-basics
- https://nph.onlinelibrary.wiley.com/doi/full/10.1111/j.1469-8137.2012.04348.x
- https://www.sciencedirect.com/topics/earth-and-planetary-sciences/plant-growth-regulator
- https://greenhouseguide.cahnr.uconn.edu/sectionD.php
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