Dig deeper to understand soils

Challenging what we’ve always thought can be enlightening, not disruptive - Country Guide Magazine, September 2020


By Ralph Pearce, Country Guide Magazine, Production Editor

What’s happening below the soil has a greater impact on crop performance and yield.

Traditions and routines can provide stability, familiarity and perhaps a sense of purpose. Yet when they keep us from exploring new possibilities — for whatever reason — there’s less room for meaningful change.


Earlier in 2020, Greg Patterson was a presenter at the Certified Crop Advisor (CCA)-Ontario chapter annual meeting in London, Ont., and created a stir when he observed that “we know virtually nothing about what happens below the surface of our fields.” That caught the attention of many who were impressed with the depth and implications of what he provided during his session.


In short, he shook many of the conventions and traditions pertaining to soil health, particularly those tied to fertility and microbial activity below the surface, all based on work he and others have conducted in the 36 years he’s been involved with A&L Canada Laboratories in London.


Patterson has worked with growers in the horticulture sector as well as in grains and oilseeds, aligning them with the soil science that he and Dr. George Lazarovitz — who joined A&L in 2009 — have been researching. His findings aren’t always accepted, and he concedes that his chemical analysis is complex. Yet he shares what he learns, not to win an argument, but because he believes it’s what’s happening in the soil.


"As a consultant working for growers, I tell them, ‘Don’t worry about what’s growing above ground, worry about the root system,’” says Patterson, a CCA and chief executive officer and founder at A&L Canada Laboratories. “The better the fertility, the better the microbiome for the plant.”


The long road to today

The journey that Patterson and Lazaro­vitz have taken from 1984 to today has involved a considerable amount of study and some intriguing premises on which they’ve built their business. The two worked together before Lazarovitz’s retirement from Agriculture and Agri-Food Canada (AAFC) in 2009, sharing insights and theories, and while they haven’t always agreed on courses of action, they almost always agree about where the data is telling them to look.


Don’t worry about what’s growing above ground, worry about the root system.” – Greg Patterson, A&L Canada Laboratories

One of the more ambitious projects Lazarovitz was involved with before he joined A&L Labs was creating a database of all soils from around the world. He worked with Dr. Sean Hemmingsen, a scientist with the National Research Council’s facility in Saskatoon, trying to “fingerprint” the soils and identify where they came from based on their microbial activity.


“They found out that it’s not the case,” says Patterson. “All soils, no matter where they come from on this planet have the same complement of bugs. They’re in different combinations and concentrations but the same organisms exist. They sequenced hundreds of thousands of organisms and found things that nobody even had names for.”


Further study on the soil microbes generated a clearer understanding of what was happening in the root zone, including the activity of several strains of bacteria that carry out different functions. Some of the research findings run contrary to current practices. For example, Patterson believes in enabling the plant to feed the soil as opposed to more conventional wisdom which says “feed the plant.” Another common belief is that diversity in cropping is the key to boosting yields.


“The plant doesn’t like diversity because it can’t sustain all of the good bugs — the microbes — because it doesn’t have enough food sources to sustain them,” says Patterson. “When the plant starts getting enough food source, it starts kicking out the bad bugs and begins to bring in more of the good bugs. It’s going to take its diverse population and reduce it down to a population of organisms that actually contribute to their community.”


What Patterson and Lazarovitz have found is that if the plant is fed the right nutrients, it can actually suppress weeds, discourage insects and reduce the potential for disease, and although Lazarovitz argues that it’s not possible to have an impact on disease through nutrition, Patterson refers to the paper he and another colleague published in 2007 that showed it is possible to control scab in potatoes using only nutrition in the soil.


“Depending on how we feed the plant, it has the ability based on environmental stimulus and what it wants to do to create these compounds to feed the right bug, to suppress the disease,” Patterson says. “But if it’s not fed right, it can’t do this.”


This is where Patterson contends the industry is going the wrong way — to stop using fertilizers. It’s not a matter of decreasing certain fertilizers, it’s determining the right fertilizers in the right concentrations. Otherwise, diseases will return and yields and quality of the crop will decrease — all because the plants aren’t being fed the way they should.


The same is true with insects and weeds. A plant will emit pheromones to attract beneficial predator species to respond to insect infestations. And weeds will grow where something like calcium is low or potassium is high.


“With proper nutrition you can almost control your weeds,” Patterson says. “You suppress them but not control.”


Good bug, bad bug

Patterson and Lazarovitz have also identified some of the activities surrounding the plant’s network of roots and have linked certain nutrients with beneficial and detrimental reactions in the root zone. Lazarovitz found that the microbial activity in the rhizosphere is key to creating the right environment for the plant. It also varies in the root zone versus the bulk soil found at lower levels.


It all comes back to feeding the right bugs, not just to suppress diseases or discourage insects, but to help the plant change the microbial population in its root zone.


“We’re struggling to put more carbon in the soil, because bugs live on that carbon,” Patterson says. “But the bugs that have an influence on how these plants perform, that are drawn into the rhizosphere by the plant, are feeding on the carbon source that the plant is distributing. It’s not from green manures or plow-down, it’s from the plant.”


In the plant, 20 to 60 per cent of the photosynthates are redistributed in the rhizosphere to feed the right bugs, and to signal and attract them to the rhizosphere. The carbon source and the bugs that are doing things are already in bulk soil, but they’re in such a diverse pool that they’re not presenting themselves because there isn’t enough food source to make them efficient.


“We understand that if you have a certain gut biome, you’re healthy,” says Patterson. “If you do something to alter that significantly and you don’t eat properly to give your body the right nutrition, the gut biome changes. The same thing happens in the soil: the gut of the plant is the rhizosphere. The plant wants to feed that gut properly to maintain that biological group.”

There’s also an important link to other players in the soil profile, like endophytes and bacteria, including Rhizobium, Pseudomonas and Bacillus species. Patterson and Lazarovitz have teamed up with researchers from Western University for help with some of the sequencing but also with a group that’s studying activity of the human gut.


As for the activity of the bacteria, the two have found that non-nodulating Rhizobium does a lot in the soil, with plenty of published material on what it does for disease and insect control in plants. It helps plants retain water around the root system and can release antibiotics that reduce diseases, and it has compounds that are biostimulants. But one of the main things it does — like Pseuda­monas — is to produce polysaccharides that aggregate soils, increasing soil tilth.

Cover crops keep the soils active and continue feeding microbes in the rhizosphere.

The effect of endophytes is another link to human health. At birth, a person is covered in beneficial bacteria that help support and protect them throughout much of their life. The same is true with plants: a plant that’s inoculated with a certain bacterium, even when transplanted, will carry that bacterium with it and create its own rhizosphere.

“A seed in rich soils will take up these endophytes — these bacteria — and that seed is the delivery mechanism for that first group of organisms to help support that plant throughout its life,” says Patterson. “So the healthier the soil is, the healthier that microbiome, and it will imbed that into the seed it produces, which it takes to the next population. We actually see a transfer of these microbes from parent plant to seed to the next generation from this evolution of building healthy soils.”

An Alphabet of Information

Patterson and Lazarovitz have also dug deeper on the relationship of many of the nutrients in the soil and found that some of the widely held concepts and recommendations in soil fertility are not exactly what the plant or its rhizosphere wants. Cutting back on phosphorus may be environmentally sound, yet healthy soils function on phosphate-solubilising bugs, and that activity is what the plant needs the bugs to do.

Other properties that Patterson has studied and included in his recommendations are the K:Mg ratio, the effect of cation-exchange capacity (CEC), per cent saturation of calcium, boron levels and the impact of pH, which he says is underrated.

“Yes, full stop,” says Patterson. “When you get a pH of 6.5, all of your nutrients are water soluble. Above or below that they become less soluble.”

Then there’s the issue of no-till production, and Patterson readily agrees that what he tells farmers at conferences may not be what they want to hear. But the research on reintroducing the plow into a no-till system is conclusive: doing it once every three to five years has no impact on the populations of good bugs. And many growers are getting the message, realizing there are some impediments to certain practices with no till, such as working in lime.

“They’re starting to put a plow back into their rotation and lime is really critical to those microbial populations,” he says. “They’re also seeing the stratification of nutrient is causing some unwanted effects, but everyone’s been told that they’re going to disrupt the microbials and destroy what they’ve developed.”

As an agronomist, Patterson believes there needs to be a greater level of awareness of “adjusting” practices. Yes, no till is a good thing, provided that fertility to depth, getting through soil stratification and working in lime are not overlooked in the chase for something more elementary.

Most of the soil health strategies currently in use are not linked to the yield or crop performance. None of them are looking at crop performance or outlining strategies, yet there are companies, including A&L Canada Laboratories, that are working on soil health strategies to improve crop performance and yield.

“We’re not just using cheap materials anymore; we’re using high volumes of fertilizer to get the yields that we’re trying to put out, and that’s going to continue,” says Patterson. “But we need to manage it, we need to work it in, we need to put cover crops on to maintain that microbial activity that we’re promoting and we need to understand how the plant is cultivating these bugs, and that the carbon sources feeding these bugs are coming from the plant.”


View the original article on the Country Guide website https://www.country-guide.ca/crops/dig-deeper-to-understand-soils/


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