Knowing your microbes takes testing, and now there is one

A & L Canada Laboratories has developed a test that assesses the microbiological component of soils, called the VitTellus Soil Health test.

The company started a research program in 2011 that used a restriction fragment length polymorphism (RFLP)-based analysis to determine the different organisms within the soil profile.

“We took a number of samples from various soils, really looking at fields that had low productivity and high productivity, and tried to isolate what group consortia of bacteria are dominant in low-producing soils versus high-producing soils,” Nevin McDougall, president of A & L Canada Laboratories, said during the Farms.com Precision Agriculture conference in Saskatoon last fall.

He said A & L characterized and categorized all the micro-organisms present in the soil samples to understand factors that have a significant correlation to both yield and microbiological populations.

The eight-year research program ended in 2017 and the company published a paper outlining the methodology in the Journal of Microbiology & Experimentation, an open access journal.

A colony-forming unit (CFU) is a type of measurement used to estimate the number of viable bacteria or fungal cells in a sample. For the study, fields with high CFUs were isolated and key factors that contributed to the microbial communities that promote high yields were identified.

“In terms of the key factors, percent potassium, K:Mg ratio, nitrate or nitrogen, pH, CEC (carbon exchange capacity), P (phosphorous) saturation and soluble salts were all top factors that contribute to developing the right microbial population in the soil that’s associated with higher nutrient utilization, higher yields,” McDougall said.

A & L’s research program examined almost 500 soil factors, including physical, chemical and biological, and correlated them to yield.

“There were the traditional nutrient metrics, percent K, nitrate, percent P, a lot of other elements around different bacteria colonies, total fungal counts, rhizobium, pseudomonas, as well as some of the antimicrobial and antifungal properties that are excreted from those bacterial colonies,” McDougall said.

The company used the results from this research to develop the VitTellus Soil Health test.

“(The test) assesses the chemical, physical and biological balance in the soil,” McDougall said.

“It’s a broader, more integrated approach to looking at our soils. The point of the assessment is to help develop strategies that improve soil health, resulting in greater nutrient utilization, translating into higher yield.”

Ontario soils were primarily used in the research, but he said the analysis works regardless of soil type.

During the on-farm trial segment of the research project, nutrient use was up to 40 percent more efficient on farms with a high soil health index compared to farms that had a low soil health index when analyzed with the VitTellus Soil Health test.

“In one particular plot, a producer was growing corn and the neighbours had a lower soil health. The amount of nitrogen used per bushel was 40 percent difference and tied directly to the metric in the soil health test,” McDougall said.

The VitTellus Soil Health index is on a zero to 60 scale and gives an indication of soil health ranging from low to high. A lower index reflects that the microbiology in the soil is lower in activity and nutrient use.

A higher index number indicates that the right microbial populations are present in the soil, as well as higher nutrient use and higher yields.

The reports provide a snapshot of 21 soil parameters and whether they are in the right range to support good soil health development.

“It’s a fairly easy straight forward chart to look at; it gives you an index of where your soils are today and starts to generate some ideas on what you might do with your client or on your farm to start making some changes,” McDougall said.

“You can do the assessment, start implementing some practices and then reassess in another two or three year time frame to see if you’ve made a difference.”

From a biological standpoint, the most active soils occur about six to eight weeks after planting.

“You have crop in the ground, it’s growing healthy, it’s feeding the microbes in the soil, so that’s the ideal time to see the maximum microbiology in the soil,” McDougall said.

However, most test users will likely take samples during the fall soil-sampling season.

“What is being recommended is to go to the same spot at the same time of year, so at least you get a consistent approach over time. Fall time is still good, as long as you’re doing it consistently year over year, or on a specific interval,” McDougall said.

The second phase of research will examine what type of cover crops best support the soil microbial populations that promote big yields.

For more information, visit bit.ly/2F5Pxiz.

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