From Chemicals to Microbes: Top 10 Biofertilizers Powering Sustainable Agriculture
- Joshua Brock
- Mar 19
- 5 min read
In an era where farmers are experiencing the rising costs of synthetic fertilizers and an increased interest in eco-friendly and sustainable practices, biofertilizers are emerging as natural alternatives to their chemical predecessors.
No longer simply the realm of homesteaders and hardcore regenerative "agvocates", food producers from both ends of the spectrum and everywhere in between are becoming aware of the many benefits of these substances, which contain living microorganisms:
improves soil fertility while helping to restore nature's nutrient cycle
reduces chemical/synthetic input costs with renewable sources of nutrients
decreases the overall reliance on synthetic fertilizers and their rising costs
boosts crop productivity with nitrogen fixation and phosphate solubilization
We're taking a deeper dive into these micro-miracles with the following topics:
Let's get started by first digging a bit more (pun intended) into what defines a "biofertilizer".
What Are Biofertilizers
Biofertilizers are substances which contain living micro-organisms, hence the "bio". When applied to the soil, the surfaces of plants, or to seeds, these substances populate either the interior of the plant or the rhizosphere which is the root region of the plants, and assist with the uptake of nutrients to the plant.
There are three categories, or common types of biofertilizers:
Mycorrhizal Fungi
Nitrogen-Fixing Bacteria
Phosphate-Solubilizing Microorganisms
Mycorrhizal Fungi
These fungi, which grow in association with the roots of a plant in a symbiotic relationship, enhance a plant's ability to absorb both nutrients and water. In particular, mycorrhizal fungi absorb phosphorus from large volumes of soil. Their hyphae (threadlike elements) increase the surface area of the roots for the uptake of nutrients.
Nitrogen-Fixing Bacteria
These forms of bacteria are widely used throughout agriculture. They form a symbiotic relationship with legume roots, creating nodules where nitrogen fixation actually occurs.
Phosphate-Solubilizing Microorganisms
Include both fungi and bacteria. The fungi, like Pencillium, solubilize phosphates, which then contribute to the availability of phosphorus. The bacteria release organic acids and enzymes, converting soil phosphates, previously insoluble, into forms that plants can then absorb.
How Biofertilizers Improve Soil Health
There are four key ways that biofertilizers improve the health of soil.
The first is by improving the structure of the soil itself. Enhancing soil aggregation leads to better aeration (air circulation), water retention, and root penetration. The combination of these three benefits results in stronger, healthier crops.
Second, an increase in microbial activity occurs. Beneficial microbes within the soil are boosted, which then helps to balance the ecosystem of the soil, suppressing harmful pathogens naturally.
Third, the soil experiences a reduction in chemical dependency. Farms can significantly reduce their reliance on synthetic/chemical fertilizers. As a result, soil toxicity is lowered, and long-term soil degradation is prevented.
Last but not least, biofertilizers help support and cultivate sustainable farming practices by minimizing environmental pollution and maintaining the productivity of soils in the long-term.
Biofertilizers vs. Chemical Fertilizers
Right out of the gate, based on the names alone, we can differentiate these two fertilizers quite simply; biofertilizers are derived from living microorganisms (bacteria, fungi, or algae), whereas chemical fertilizers are manufactured via chemical processes from minerals or synthetic compounds.
As discussed just a bit ago, biofertilizers contain beneficial microbes, like Rhizobium (nitrogen-fixing bacteria), phosphate-solubilizing bacteria, or mycorrhizal fungi. Chemical fertilizers include nutrients that have been concentrated, such as nitrogen, phosphorus, potassium, or micronutrients in their pure chemical forms, such as vitamins, minerals, and antioxidants.
Next, there are differences in their mechanisms of action. Chemical fertilizers directly supply nutrients that plants will then absorb without microbial activity, whereas biofertilizers improve nutrient availability via nitrogen fixation, phosphorus solubilization, or through the decomposition of organic matter.
In the column of other benefits, biofertilizers provide improved soil health, reduced environmental impacts, increased duration of nutrient supplies, lower long-term costs, improved crop yields, sustainability over dependency, and improved microbial life in the soil.
Feature | Biofertilizers | Chemical Fertilizers |
Source | Microorganisms | Synthetic/mineral |
Composition | Beneficial microbes | N, P, K, micronutrients |
Mechanism | Biological nutrient cycling | Direct nutrient supply |
Soil Health | Enhances fertility | Can degrade soil |
Environmental Impact | Eco-friendly | Can pollute water & soil |
Nutrient Duration | Slow, sustained | Quick, short-term |
Cost | Low, long-term savings | High, recurring cost |
Application | Seeds, soil, seedlings | Soil, water, foliar spray |
Crop Yield | Gradual improvement | Immediate increase |
Sustainability | Promotes self-sustaining soil | Creates dependency |
Microbial Life | Enhances diversity | Can harm microbes |
Storage | Limited shelf life | Long shelf life |
Regulation | Microbial quality | Nutrient content standards |
Source: Agriblossom.net
Top 10 Biofertilizers
Let's take a very quick look at ten of the current top biofertilizers:
Rhizobium - Nitrogen-fixing bacteria for leguminous crops like soybean, chickpea, etc. Read more about the use of this here.
Azospirillum - Associates with cereals & grasses, enhancing nitrogen availability and root growth. Read more here.
Azotobacter - Free-living nitrogen fixer used for vegetables, cotton, and non-legume crops. Read more here.
Blue-Green Algae (Cyanobacteria) - Nitrogen fixers in paddy fields, improving waterlogged soils naturally. Read more about this here.
Azolla - A floating fern in rice paddies that fixes atmospheric nitrogen efficiently. Read more about the use here.
Phosphate Solubilizing Bacteria (PSB) - Solubilizes insoluble phosphorus, making it available to plants. Read more about the use here.
Mycorrhizae (Vesicular-Arbuscular Mycorrhizae - VAM) - Enhances phosphorus & micronutrient uptake through symbiotic root association. Read more about the use here.
Potassium Solubilizing Microorganisms (KSM) - Mobilizes bound potassium in soil, essential for plant vigor & yield. Read more about the use here.
Plant Growth Promoting Rhizobacteria (PGPR) - Promotes overall plant health, disease resistance, and nutrient uptake. Read more about the use here.
Sulphur Oxidizing Bacteria (Thiobacillus spp.) - Improves sulfur availability in alkaline soils, essential for oilseeds & pulses. Read more about the use here.
With any new approach to farming, it's important to do your research. Any of these fertilizer types has different risks and advantages to take into account.
Environmental Benefits of Biofertilizers
We've already touched on a few of the environmental benefits of biofertilizers, such as natural soil enrichment, reducing chemical pollution, and improving soil health, but there are a handful of others.
Another related benefit comes in the form of reduced greenhouse gas emissions, and this happens both in the production of and the application of chemical fertilizers. Biofertilizers are organic by nature and thus do not contain synthetics, reducing chemical pollution. Their use lessens the flow of pollutants into rivers and lakes and the leaching of dangerous chemicals into groundwater.
The manufacturing of chemical fertilizers, especially those that are nitrogen-based, is energy-intensive and once again increases greenhouse gas emissions. Reducing the demand for chemical nitrogen fertilizers, such as nitrogen-fixing biofertilizers, nitrous oxide (N2O), a strong greenhouse gas, is released less frequently.
Biodiversity is also a consideration that lands in favor of biofertilizers. As discussed, with their promotion of a thriving microbial ecosystem in the soil, a related side benefit is the biodiversity of the soil itself.
And finally, as a stepping stone in this journey, comes enhanced resilience to a changing climate. Soils that are enriched with biofertilizers are better equipped to withstand climate extremes, which include both droughts and heavy rainfall. This resilience is increasingly important as climate variability becomes more pronounced.
Biofertilizers: A Powerful Shift in Soil Fertility and Crop Nutrition
Farmers can now harness the natural power of beneficial microorganisms to restore soil health, improve nutrient availability, and support long-term agricultural productivity by embracing biofertilizers. By working with nature rather than against it, all growers, whether they be small family farms or the largest of agricultural operations, can build healthier soils, more resilient crops, and a more sustainable future for agriculture. Biofertilizers offer a practical and sustainable alternative to chemical fertilizers as concerns grow over environmental impact, fertilizer costs, and soil degradation.
Joshua, his wife Jenn, and their dog Rooster live in PA. Joshua is the owner and operator of Hoffman Appalachian Farm, where they grow Certified Naturally Grown hops. Joshua has over twelve years of experience in growing crops, including growing in an organic system. In his spare time, he enjoys trail running, backpacking, and cycling.