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Exploring the science behind microbial fertilizers and soil probiotics

Published online: Aug 06, 2018 Articles, Fertilizer
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This article appears in the August 2018 issue of Potato Grower.

Potato growers are always looking for new ways to produce earlier harvests, as well as increase their return on investment. But often, the fear of trying something new can hold a grower back. Experience from others who have saved time, money and manpower by changing their ways can remove some or all of the fear of failure.

Soil probiotics and microbial fertilizers are not new. The commercial history of bacterial soil amendments began in 1895 with the launch of Nitragin, a laboratory culture of Rhizobia. Since then, companies have continued creating better ways for the nutrients in the soil to be functional for plants.

Microbial fertilizers offer a new technology to potato growers, balancing many of the shortcomings of conventional chemicals and continuing to improve soil fertility and productivity.

What Are Soil Probiotics?

Bacterial soil amendments, or soil probiotics for the soil, improve nutrient uptake by making them more bio-available, promoting a plant’s vigor and growth. When applied to soil, the beneficial microbial populations come to life and begin multiplying.

“Without vibrant beneficial microbes in the soil, plants are unable to reach their full potential,” says Simon Neufeld of Earth Alive Clean Technologies, makers of Soil Activator. “Plants cannot use the soil’s natural fertility or efficiently absorb added fertilizers. A product like Soil Activator boosts the soil’s natural microbe communities while also adding specially selected, highly functional microbes to the mix.”

These soil amendments are easy to use. Coming in liquid, granular or powder forms, the method of application depends on their concentration and form. Granular forms are generally applied dry, either alone or in combination with other amendments. Liquid products can come pre-mixed or concentrated, and must be applied with water. Powder-based amendments are the most versatile, because they can either be mixed with water and drenched into the soil, or mixed directly into the growing media for container growing. For example, a 55-pound package of Earth Alive’s Soil Activator—a dry powder microbial fertilizer—will treat 20 acres of potatoes when used as a water-based solution and applied in-row. (See the product’s technical documentation for more specific instructions.) Best results are seen when the product is applied early in the season, ideally at the time of emergence, to give the microbes the best runway to do their job.

Why to Consider Using Soil Probiotics

Microbial fertilizers offer advantages to all types of growers.

“Years of tillage and other conventional farming practices can lead to a decline in native biology,” says Neufeld. “When growers add functional probiotics to the soil, plants can thrive.”

In the case of a potato farm in the Machachi region of Ecuador, by simply drenching the soil with Soil Activator, potato production was improved. Plants grew greener and more vigorous vines, were better able to fight off diseases and pests, and yielded 10 percent higher on average. Soil Activator creates vigorous plants and higher yields, with reduced fertilizer and water use, ultimately lowering production costs.

Trial Results

The blend of naturally occurring micro-organisms in Soil Activator has garnered worldwide recognition and is proven to boost yields of dozens of crops, increasing profitability for growers.

Neufeld says Earth Alive has received great feedback from growers with potatoes, where plants were observed to be greener and more vigorous, with more extensive root systems. Pre-harvest samples showed that treated potato plants produced about 30 percent more potatoes by weight than the untreated plants. The treated plants also showed fewer undeveloped tubers—representing additional income for the grower that the control plants did not generate. At harvest, the treated plot generated a 39 percent higher yield than the control plot, and 10 percent more high-grade tubers.

“Soil Activator is an effective, consistent and high-quality product that puts functional biology right in the root zone, ensuring that potato roots are surrounded by beneficial microbial activity throughout the growing season,” says Neufeld. “Growers need to think about how their production methods support or inhibit biological activity in the root zone of their plants. Intensively managed growing systems have to optimize not just the physical and chemical environments for the plants, but also the biological environment.”

Additionally, many growers want to contribute positively to the ecological health of their farms, and certified organic acres are increasing steadily from year to year. Soil Activator is OMRI-listed for organic use, containing no genetically modified organisms or synthetic chemicals. It can also be used in conventional growing, allowing the grower to use less fertilizer to gain the same or better results.

Ultimately, through trials and tests, soil probiotics have proven to produce more vigorous growth and higher yields, resulting in more sustainable agricultural practices and increased profitability for growers.


To learn more about Earth Alive and its Soil Activator product, visit