Bradyrhizobium Japonicum Manufacturer & Exporter | Nitrogen Fixing Bacteria | Microbial Species

Bradyrhizobium japonicum

Bradyrhizobium japonicum is a nitrogen-fixing bacterium that plays a crucial role in soybean cultivation. By forming symbiotic nodules on soybean roots, it converts atmospheric nitrogen (N₂) into ammonia (NH₃), a form that plants can readily use for growth. This natural nitrogen fixation process significantly boosts nitrogen availability, leading to improved plant health, increased crop yield, and reduced dependence on synthetic fertilizers. Bradyrhizobium japonicum is vital for promoting sustainable agricultural practices while enhancing soil fertility in legume-based farming systems.

Strength

1 x 10⁸ CFU per gram / 1 x 10⁹ CFU per gram / 1 x 10¹⁰ CFU per gram

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Benefits

Nitrogen Fixation

Rhizobium japonicum forms a symbiotic relationship with leguminous plants, particularly soybeans, to fix atmospheric nitrogen into ammonium (NH₄⁺). This process significantly enhances soil fertility and supports plant growth by providing a sustainable source of nitrogen, crucial for protein synthesis and overall plant health

Soil Improvement

In addition to nitrogen fixation, R. japonicum improves soil structure and fertility over time by enriching it with bioavailable nitrogen and organic compounds. These contributions, facilitated by root exudates and nodulation, enhance nutrient cycling within the rhizosphere

Nodulation

This bacterium induces the formation of nodules on the roots of leguminous plants. Within these nodules, nitrogenase enzymes convert atmospheric nitrogen into usable forms, ensuring an optimal environment for nitrogen fixation

Increased Crop Yield

By supplying fixed nitrogen directly to the host plant, R. japonicum enhances crop yields, especially in nitrogen-depleted soils. The symbiotic relationship helps crops thrive in nutrient-poor environments, significantly reducing the need for synthetic fertilizers

Scientific References

Comprehensive genome analysis of Bradyrhizobium japonicum reveals key nif gene clusters enabling efficient nitrogen fixation in soybean nodules (J. Bacteriol., 2019).
Field trials demonstrate inoculation with B. japonicum increases soybean yield by up to 25% and reduces synthetic N fertilizer requirements by 50% (Agron. J., 2021).
Meta-analysis of legume-rhizobia symbioses confirms B. japonicum strains deliver superior nodulation, nitrogenase activity, and soil health improvements compared to fast-growing rhizobia (Soil Biol. Biochem., 2022).
Classic field evaluation of three B. japonicum strains (USDA 110, USDA 138, TAL 379) established long-term benchmarks for field nodulation and yield performance in clay-loam soil (Moawad, Plant and Soil, 1988).
LSU AgCenter extension research indicates biological nitrogen fixation can supply 40-70% of a soybean crop's total nitrogen requirement under favorable conditions, and recommends seed inoculation whenever soybean has not been grown in a field before (Wang, Moseley & Parvej, LSU AgCenter).

Mode of Action

Bradyrhizobium japonicum infects soybean root hairs and induces cortical cell division, forming specialized root nodules where the nitrogenase enzyme complex converts atmospheric N₂ into NH₄⁺.
The bacterium's symbiotic genes (nodABC) synthesize lipochitooligosaccharide signals (Nod factors) that establish host specificity and trigger nodule organogenesis.
Within nodules, B. japonicum regulates oxygen concentration via leghemoglobin to protect nitrogenase from inhibition while supplying fixed nitrogen to the plant in exchange for carbon substrates.
Nodulation begins when soybean roots exude flavonoid compounds such as genistein and daidzein, which activate the bacterial NodD regulatory protein and switch on the nod gene cluster responsible for Nod factor synthesis.
Because Bradyrhizobium japonicum forms indeterminate nodules with a persistent meristem, a single successful infection can sustain nitrogen fixation for most of the soybean growing season — unlike the determinate nodules formed by fast-growing rhizobia on beans and peas.
Real-world performance also depends on nodule occupancy: the inoculant strain must out-compete naturalized soil bradyrhizobia for available nodule sites, which is why seed-treatment quality, application timing and soil conditions influence field results as much as strain selection.

Additional Info

Recommended Use: Soybean (primary commercial host). Field and research trials also show benefit in other legumes such as Bambara groundnut and Lablab purpureus, though soybean remains the primary commercial application. Not effective on non-leguminous crops (cereals, vegetables, fruit crops).

Optimal Soil Conditions: Soil pH 6.0-8.0; soil moisture 60-70% of field capacity; organic matter above 1.5% for best establishment.

Expected Results Timeline: Improved root vigor and nodulation typically visible within 3-4 weeks; full yield benefit is realized at crop maturity.

Storage Conditions: Store in a cool, dry place away from direct sunlight and temperatures above 30°C; refrigeration between 4-25°C further extends viable cell counts. Do not freeze.

Handling & Safety: Keep the product sealed until use, wash hands after handling, and store away from chemical fertilizers and pesticides to protect live bacterial cell counts. Keep out of reach of children.

Compatibility: Compatible with Bio Pesticides, Bio Fertilizers, and Plant growth hormones but not with chemical fertilizers and chemical pesticides.

Shelf Life: Stable within 1 year from the date of manufacturing.

Packing: We offer tailor-made packaging as per customers' requirements.

Dosage & Application

Seed Treatment: Apply 100 g of inoculant per 100 kg of soybean seed (0.1% w/w). Prepare a sticker solution of non-chlorinated water with 10% sugar or gum arabic, moisten the seed, coat evenly with Bradyrhizobium japonicum powder, and air-dry in shade. Plant within 24 hours of treatment for maximum viability.

In-Furrow Application: Apply 500 g/ha directly into the seed furrow at planting. Ensure soil is moist for optimal microbial survival, and apply as close to seeding time as possible.

Soil Treatment: Broadcast 500 g/ha evenly over the soil and incorporate lightly with tillage, or apply through irrigation, at pre-planting or the early vegetative stage.

Foliar Application: Mix 750-1000 g/ha with 500-1000 liters/ha of water and spray during early-to-mid vegetative growth. Seed or in-furrow placement remains the most effective method for nodulation; treat foliar application as a supplemental option.

Recommended Microbial Load: Seed treatment 10⁷-10⁹ CFU per gram of seed; soil and in-furrow application 10⁹-10¹² CFU/hectare to ensure effective root colonization and nodule formation.

Water Quality: Use non-chlorinated water (below 2 ppm chlorine) for all slurries and tank mixes — chlorine levels above this can kill the live bacteria. Use any prepared suspension within 24 hours.

FAQ

What is the difference between Bradyrhizobium japonicum and Rhizobium species?

Bradyrhizobium japonicum is a slow-growing, thermotolerant bacterium that forms indeterminate nodules with a persistent growth zone on soybean roots. Fast-growing genera such as Rhizobium leguminosarum form determinate nodules on beans, peas and lentils instead. The two groups are taxonomically distinct, even though the older name "Rhizobium japonicum" is still used informally.

What are the benefits of using Bradyrhizobium japonicum on soybean?

Inoculation improves nodulation and nitrogen fixation, increases biomass and yield, reduces dependence on synthetic nitrogen fertilizer, and supports beneficial microbial diversity in the root zone. LSU AgCenter research indicates biological nitrogen fixation can supply 40-70% of a soybean crop's total nitrogen requirement under favorable conditions. See our guide to nitrogen fixation for background on the process.

How is Bradyrhizobium japonicum applied to soybean seed?

The most common method is seed treatment: coating seed with inoculant powder using a sugar or gum-arabic sticker solution immediately before planting. In-furrow and soil application are also effective where seed treatment isn't practical. Full application rates are listed in the Dosage & Application section above.

Does soybean need to be re-inoculated every year?

Inoculation matters most in fields where soybean has never been grown, since no compatible bradyrhizobia are yet present in the soil. Once established, native populations can persist for several seasons, but re-inoculation is still recommended after 3-5 years without soybean in rotation, or whenever nodulation has been inconsistent, since the inoculant strain must stay competitive against naturalized soil populations. Learn more in our nitrogen-fixing bacteria overview.

Can Bradyrhizobium japonicum be combined with other biological inputs?

Yes. It is compatible with other biofertilizers and plant growth-promoting microbes, including phosphate-solubilizing strains such as Bacillus megaterium, and with plant growth hormones. Avoid tank-mixing or seed-coating it together with chemical fertilizers or chemical pesticides, which can reduce viable cell counts.

Is Bradyrhizobium japonicum specific to soybean, or does it work on other legumes?

Bradyrhizobium japonicum is host-specific to soybean and a small number of related legumes such as Bambara groundnut and Lablab purpureus; it will not nodulate beans, peas, lentils or non-leguminous crops. For those crops, see our rhizobium and legume nutrition guide or the Bradyrhizobium elkanii page for peanut and groundnut inoculation.