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How P-Solubilizing Products Work

Bacillus firmus unlocking Phosphorus

How P-solubilizing products work is the second of five blogs in our deep dive series into Phosphorus (P)-solubilization. In our last blog we covered the What of P-solubilization. To recap inorganic phosphorus (P) is negatively charged in most soils. Because of its particular chemistry, P reacts readily with positively charged calcium (Ca), iron (Fe) and aluminum (Al) ions to form relatively insoluble substances. This P needs to be solubilized to become plant available.

This week we will dig into the How of microbial P-solubilization.

  1. How naturally occurring soil microbes solubilize P
  2. How to turn nature into technology
  3. How to commercialize the technology

There are plenty of microbes present naturally in prairie soils (estimated over 1 billion per gram of soil) (1). Among them exist naturally occurring P-solubilizing bacteria. The potential of P-solubilizing bacteria on commercial agriculture has been recognized since the 1980’s (2).

As scientists isolated these bacteria in labs to study them, they discovered the mechanisms behind the bacteria’s P-solubilizing properties.  P-solubilizing bacteria produce natural enzymes that affect soil pH and break the bonds connecting the Fe, Al and Ca to the P. These enzymes are called phosphatase enzymes. They are produced by bacteria, fungi and plant roots and their function is to break phosphate away its substrates transforming unavailable forms of P into plant available forms of P (3).

But it’s not just how the bacteria react with P in the soil but also their relationship with the roots of the plant that makes them special. The main pathway for P uptake is through the roots and specifically the root hairs of the plant. Many P-solubilizing bacteria (like Bacillus firmus) can change the structure of the plant roots by synthesizing plant growth promoting hormones. This can have the effect of decreasing the overall length of the root but of increasing the length of the root hairs. Because P is most accessible in the rhizosphere (root zone) this directly enhances the plant’s ability to uptake solubilized P in the vicinity of the root (4).

Phosphatase enzymes can work on different kinds of P:

  • Rock phosphate for organic applications
  • Soil bound P
  • Applied commercial P fertilizers

It is one thing to say in an academic sense that there are naturally occurring P-solubilizing microbes in the soil. But those microbes need to be isolated, tested and reproduced to be considered a technology. Hence, XiteBio® isolated, tested and reproduced Bacillus firmus in our IRD lab to an extent that we were able to obtain a worldwide patent on its use. Still the challenge was to create a commercial product. To see wide adoption and perform with consistency inoculant technology must be:

  1. Cost effective
  2. Uniform in formulation
  3. Ready-to-use
  4. User friendly

When XiteBio® decided to bring XiteBio® Yield+ to market we had to make the leap from applied technology to commercial technology. This was achieved through:

  • Development of a proprietary delivery medium
  • Controlled fermentation in discreet batches
  • Continuous & rigorous QA/QC performed on the product
  • Pricing to ensure ROI for growers.

Many companies in the ag-biological space claim to have found a revolutionary bacterium or fungus but if they are not following proper procedures to bring a consistent product to market then it can fail in the field. And that failure hurts not only the one company but the credibility of the ag-biologicals industry as a whole.

Every company tends to develop proprietary formulations or processes or trade secrets around their technology. At XiteBio® Bacillus firmus forms the basis of our PGPR products but the proprietary formulations ensure the consistency of the products year after year. While companies cannot be expected to divulge trade secrets or proprietary technologies, they should by and large be able to explain the broad strokes of how P-solubilizing products work. As a farmer It is important to do your due diligence and as such it is your right to ask: How a technology works and How it is guaranteed in commercial applications to provide the performance it claimed.

 

References:

  1. https://ohioline.osu.edu/factsheet/SAG-16
  2. https://www.jstor.org/stable/44506926
  3. https://www.nature.com/articles/s41598-017-01418-8#Sec1
  4. https://www.frontiersin.org/articles/10.3389/fpls.2017.01834/full

 

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