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This Crop File contains excerpts and summaries from “Performance of Selected Commercially Available Asymbiotic N-fixing Products in the North Central Region”.
The research trials in this publication included biological-based products that claim to either infect the seed or the plant foliage which then enables the microorganisms to perform nitrogen fixation functions similar to Rhizobia in legumes, or to inhabit the soil immediately outside the root (rhizosphere) and use plant-root exudates as food-stuffs, enabling the nitrogen-fixing organisms to fix nitrogen from the air.
(https://www.ndsu.edu/fileadmin/snrs/Files/SF2080_Performance_of_Selected_N-fixing_Products.pdf, issued 17 April 2023)
- Included sixty-one (61) site years of nitrogen rate trials with and without the use of biological nitrogen-fixing products.
- Trials conducted with corn, spring wheat, sugarbeets and canola.
- Sites included ten states within the North Central Region of the U.S during crop years 2020 to 2022.
- Of the 61 site-years, 59 site-years had no yield increase with use of the product over nitrogen rate alone.
- Two site-years in corn had yield increases due to product use over the N rates alone. The nitrogen rate benefit ranged from 12 to 20 lb N/ac.
Asymbiotic or non-symbiotic nitrogen-fixing organisms, usually species of bacteria, have the ability to ‘fix’ atmospheric nitrogen gas (N2) gas to produce ammonia (NH3). They are free-living organisms found in the soil and are not associated with specific plants or fungi, unlike the symbiotic Rhizobia bacteria associated with legume plants.
There are many species of asymbiotic bacteria, including those of the genera Azotobacter and Clostridium, but many others as well.
The activity of all of these nitrogen-fixing bacteria is linked to the substrate (i.e., food source) and soil condition. Asymbiotic nitrogen fixation is highly dependent on soil temperature and soil moisture. Moist soil and warm temperatures produce greater activity.
The process used to fix nitrogen by asymbiotic organisms is highly energy intensive. If nitrogen-fixing organisms are active inside living plant tissue, the energy for nitrogen fixation has to come from the plant itself.
The energy required by asymbiotic organisms to fix nitrogen may come from a variety of sources depending on their presence in the surface soil. The food sources may be soil organic matter, intermediary compounds during the process of plant/animal decay, or the decay of other microorganisms. A rich source of energy also comes from root exudates that are secreted by growing plants into the soil immediately surrounding the roots, known as the “rhizosphere”. The rhizosphere serves as a home to many microorganisms.
- Produced by Azotic, Guelph, Ontario, Canada
- Label lists Gluconacetobacter diazotrophicus. as active organism
- Labeled for in-furrow, seed, and foliar application
- From label: “Inoculant colonizes plants for new or improved nitrogen fixation. May allow less nitrogen input to maintain crop yield. May enhance crop yield when applied with full nitrogen fertilizer program.”
- Produced by Corteva Agrisciences, Indianapolis, IN
- Label lists Methylobacterium symbioticum as the nitrogen-fixing organism.
- Labeled for foliar application.
- From label: “Inoculation with Methylobacterium symbioticum SB23 from Utrisha N can result in improved crop yield.”
- Produced by Pivot Bio, Berkeley, CA
- Safety Data Sheet (SDS) readily available from website, but not product label.
- SDS lists Klebsiella variicola as the inoculant bacteria.
- Produced by Pivot Bio, Berkeley, CA
- Safety Data Sheet (SDS) readily available from website, but not product label.
- SDS lists Kosakonia sacchari and Klebsiella variicola as the nitrogen-fixing bacterial organisms.
- To be applied in-furrow to corn or grain sorghum.
- Produced by TerraMax, Bloomington, MN
- Labeled as seed treatment for wheat.
- Label lists Azospirillum lipoferum and Azospirillum brasilense as the active bacteria species.
- Produced by Biovante, Augusta IL
- Label lists Azotobacter vinelandii, Colstridium pasteurianum, Azotobacter chroococcum and Lactobacillus acidophilus as free-living soil microbes.
- Labeled for preplant soil application.
- Produced by Biovante, Augusta IL
- Label lists nitrogen-fixing organisms Azotobacter vinelandii and Lactobacillus acidophilus.
- Product contains 32% of various sugars.
- Label states, “BioMate acts as a biological food source to increase the efficiency of BioRed.”
- Labeled for preplant, in-furrow, foliar, and side-dress (with UAN) applications.
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