Greenhouse Canada

Technology Issues: Could adding soil probiotics be beneficial for business?

Exploring the science behind microbial fertilizers.

August 21, 2018  By Earth Alive

Soil probiotics and microbial fertilizers are not new. Known as ‘biofertilizers’, their history began with the launch of ‘Nitragin’ in 1895. This product contained nitrogen-fixing rhizobia originally isolated from the roots of legume crops, then cultivated for application.

This beneficial microbe would form a ‘symbiotic relationship’ with the plant, increasing the number and size of root nitrogen-fixing nodules to increase nitrogen availability in the plant.

Because crops have different nutritional needs and relationships with different microbes, microbial fertilizer formulations have to be tailored towards different types of greenhouse crops. It’s not a new concept for many field crops, but adapting this technology for greenhouses helps balance many of the shortcomings of conventional chemicals, while continuing to improve soil fertility and productivity.


What are soil probiotics?
If soil is like the stomach of a plant, then biofertilizers are “probiotics for the soil.” Nutrients can be hidden in plain view, unavailable to plants because they are locked up as insoluble minerals or in slow-to-decompose organic matter.

Scientists look for specific microbial strains in the soil that can enhance plant growth. When applied to soil, they can stimulate natural microbial communities, while also adding highly functional natural microbes that have been selected.

For best results apply early in the season, ideally at the time of planting, to give the microbes time to settle in, multiply and produce a range of enzymes and other compounds that help to break down organic matter, solubilize minerals and fertilizers, and conserve soil moisture.

The method of application depends on the concentration and form (liquid, granular or powder). Granular forms are generally applied dry, either alone or in combination with other amendments. Liquid products can come premixed or concentrated, and must be applied with water. Powder-based biofertilizers are more versatile, because they can either be mixed with water and drenched around the root area, or mixed directly into the growing media. A soluble powder formulation can also offer better shelf stability and better ease of mixing with water, for application through an irrigation system or spraying equipment.

What to consider
“Many greenhouses grow in soilless media, which can be deficient in native biology,” explains Simon Neufeld, director of soil management at Earth Alive Clean Technologies.

For Benjamin Thauvette, owner of Les Serres Chlorophylle greenhouse in Quebec, he adds a powder-based microbial fertilizer to his hanging baskets. Flowers treated for Mother’s Day were on time, in full-bloom and showed outstanding colours, says Thauvette. “And vegetable plants fought off diseases and pests better than those that were not treated. So in the end, we had more plants for sale and less headache.”

According to Neufeld, tomato and pepper greenhouse growers using microbial fertilizer saw taller vines, more fruit and higher yields. Roses and other greenhouse ornamentals have also responded well, with greener leaves, and more and longer flower stems.

“Growers should think about how their production methods support or inhibit biological activity in the root zone of their plants,” explains Neufeld. “Intensively managed growing systems have to improve not just the physical and chemical environments for the plants, but also the biological environment.” It’s important that plant roots are surrounded by beneficial microbial activity throughout the growing cycle, he adds, to ensure that plants have access to the resources they need to maintain growth.

For organic growers, OMRI-listed biofertilizers are approved for organic use, containing no genetically modified organisms or synthetic chemicals. They can also be used in conventional growing, allowing the grower to use less fertilizer.

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