One aspect of soil health

By JW Lemons

As a crop consultant, soil health means numerous things. I look for soil with adequate water-holding capacity for its depth, structure and makeup. What kind of soil do I have? Sandy loam or a heavier clay? What is my cation exchange capacity? Can this soil hold nutrients long term or will they leach? Are salt contents or water quality decreasing soil health? Is organic matter or carbon content present to promote healthy microbial activity and natural plant nutrition? These factors help build and maintain soil health. One area I’ll highlight is adding rhizobacteria to the soil or seed through inoculants.

One key rhizobacteria I have used is Azospirillum brasilense, a free-living, nitrogen-fixing bacterium found in several products. It promotes root development and improves nutrient uptake, particularly in corn. It’s commonly associated with grass and cereals like maize, wheat and rice.

Symbiotic and sustainable describe the rhizobacteria Azospirillum. Hidden beneath the soil surface, microscopic organisms work 24/7 to improve plant health and growth. Beyond nitrogen-fixing benefits, Azospirillum produces phytohormones that stimulate root elongation and branching, leading to robust root systems and better nutrient uptake. It’s widely used in biofertilizer and sustainable agricultural practices aimed at improving plant health and productivity without relying heavily on chemical inputs.

The working mechanism of Azospirillum

To improve soil microbial diversity, farmers can implement crop rotation with varying nitrogen and carbon ratios. Just as organic fertilizer like animal manure invites beneficial microorganisms back into the soil, Azospirillum assists in the nutrient cycle process.

Benefits of Azospirillum for plant growth 

Like some practical biostimulants, Azospirillum can:

• Facilitate plant growth. Azospirillum promotes plant growth by improving nutrient availability through biological nitrogen fixation, helping plants absorb water and nutrients more efficiently, resulting in stronger, healthier plants.

• Promote resilience. Azospirillum enhances plant resilience to environmental stresses, including drought, salinity and heavy metal toxicity through improved root development and stress-protective compounds.

• Improve overall plant health. By improving nutrient availability, enhancing root growth and boosting stress tolerance, Azospirillum contributes to overall plant health and vigor, leading to bigger yields, improved crop quality, and reduced reliance on synthetic fertilizers and pesticides.

Practical applications of Azospirillum biofertilizer

• Biofertilization. Azospirillum is widely used as a biofertilizer to enhance nitrogen fertility, supplementing synthetic nitrogen fertilizers.

• Seed inoculation. Seeds can be inoculated with Azospirillum before planting, ensuring plants benefit from nitrogen-fixing ability from early growth stages. This improves stand establishment, root development and overall plant health.

• Soil treatment. Azospirillum can be applied directly to the soil using in-furrow application at seeding, enriching the soil microbial community and improving soil fertility utilization.

Understanding the potential of Azospirillum unlocks possibilities for sustainable agriculture. By harnessing these beneficial microbes, we can improve crop yields, enhance soil health and reduce reliance on synthetic inputs.

JW Lemons is a Certified Crop Adviser and Certified Professional Agronomist with Verdesian Life Science and executive board member of the Western Region Certified Crop Advisers. 

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