Jeff Schoenau gets a variation of the same questions several times a year — on the phone, over coffee, via email or somewhere on the winter meeting circuit. “They basically all want to know, ‘What do you think of product XYZ?’” the University of Saskatchewan soil fertility specialist says.
That can be a tough question for an academic to answer as very little third-party research is ever done on commercial products these days, and typically research work by him and others in his field deals with larger basic questions such as how to manage soil fertility and run-off.
“I basically can’t give an informed, scientific response, because I haven’t worked with it,” he says.
But the continuing nature of these inquiries suggests that there is a need for primary producers to be able to sort fact from fiction. With that in mind, he’s on the meeting circuit this winter offering some practical guidelines for growers.
Do claims stack up?
At the recent Manitoba Agronomists Conference in Winnipeg, he told agronomists and farmers that the first test will always be the “smell” test — do the claims stack up with what we know about how soil science works?
“Do the claims fall within the laws of nature?” he asked, followed by a slide of a decrepit old outhouse appearing on the screen. “Or are they more like the call of nature?
“It’s hard to make something out of nothing, so ask yourself, how are we going to get 100 pounds of nitrogen from something you’re going to add at one pound an acre?”
When a product is at the early stages of commercialization, it can be a tough thing to find much meaningful information, Schoenau says. Typically the companies rely on lab and greenhouse studies that may or may not translate into the field. He also cautions that product testimonials shouldn’t necessarily be taken at face value, since they’re frequently in the realm of anecdote, not evidence.
“A testimonial is fine, but is there a name and contact information? That becomes a bit more meaningful.”
In the field there’s typically contract research by privately owned research facilities commissioned by the manufacturer, which can be another source of information, but still tend to be small-plot trials which may not translate to field-scale results.
Another source of information might be published articles, but he cautions they need to be critically examined too. Look for who wrote it, what their credentials are and if there’s any doubt, contact them with your questions.
One of the best sources of information comes from government agencies that may regulate these products like the CFIA and PMRA. Those organizations have high scientific standards and frequently require efficacy trials.
“That is only available, of course, where it’s appropriate,” Schoenau said.
If there still isn’t enough information to make a decision you’re comfortable with, there’s another call you can make — to the company marketing the product.
“Ask them, ‘Can I have a demonstration?’” Schoenau said. “Doing and seeing is believing.”
But these guidelines don’t eliminate the basic shortfall — a knowledge gap that requires scientific evidence.
To address it, Schoenau and his fellow faculty members at the university have designed a new program for their advanced thesis students, based on one of the agriculture science classes where they’re required to design an experiment.
Do it yourself
The intention is to familiarize the students with the scientific method, and Schoenau says in the past couple of years they’ve been having students test available commercial products.
He cited the work of student Gisele Ulrich during his presentation, who examined enzymes as soil additives.
To test their efficacy, Ulrich planted samples in a phosphorus-deficient soil, with four replications at various rates of the amendment and four without any additive. After growing it she measured phosphorus and nitrogen uptake, and soil residual available phosphorus and nitrogen. She also measured the biomass.
“There was no significant difference in yield, no significant difference in biomass and no significant difference in phosphorus or nitrogen uptake or residual,” says Schoenau. “The enzymes didn’t really seem to do anything.”
He went on to stress that the study still didn’t provide a definitive answer, since there could be variables outside the scope of the experiment that altered its outcome — say for some environmental reason the enzymes were inactivated and decomposed before they could have an effect.
Bioproducts are affected by complicated factors — they may have a positive effect in one environment or one season, and not another, he noted.
“But we do know that on that soil, and that crop, at that rate, there was no apparent effect,” he says.
“One of the things I have to remind my students is that performing an experiment and getting no result can be just as important as getting a dramatic result — in some cases it may be even more important.”
For farmers and agronomists he recommends asking questions and seeking evidence when considering new products. He cautioned them to be open minded and fair and to acknowledge that there can be variables in any experiment, and to continue to update their knowledge and be willing to learn. He also suggested that if there was no good evidence, they might consider creating their own.
“You could build a simple light tray, get some pots and soil, and perform your own experiment,” he said. “You can do what our fourth-year thesis students are doing.”