Research shows biochar can help with root rot

REDVERS, Sask. — Biochar show promise in the quest to manage root rot in pulse crops.

Plots at the South East Research Farm clearly show the advantage of the product, as those treated with it are doing much better than those without.

Agriculture Canada researcher Michelle Hubbard has been working on root rot solutions for years.

She said it’s exciting to work on something that might actually work instead of finding things that don’t.

Collaborator Lana Shaw, SERF’s executive director, likened the process to throwing spaghetti at a wall to see what sticks.

This project came out of previous trials Hubbard started during the pandemic on using calcium to interrupt the life cycle of aphanomyces.

“Our thinking there was that if we added lime as a source of calcium to the soil, that could interfere with the ability of the aphanomyces to infect,” she said.

Multi-site trials with different liming products followed.

At Swift Current, Sask., where Hubbard is based, that trial used gypsum, while in Alberta, where Syama Chatterton was leading the project, the trial used spent sugar beet lime.

Hubbard said none of the liming products worked, but the gypsum did somewhat.

She continued to work on gypsum and started combining it with other things because gypsum can help with salinity, for example.

That led to the work with biochar.

Raju Soolanayakanahally had been working with biochar as a soil amendment at the Indian Head research farm in Saskatchewan.

Hubbard said she thought it could work in combination with something else she was working on, which is biocontrol by increasing soil porosity to create habitat for beneficial bacteria. This could potentially reduce compaction, which is a risk factor for root rot.

Hubbard said gypsum was tested last year at several sites and had a strong effect at Redvers. It reduced root rot at only that location.

She said one factor could be that the soil there has a more neutral pH compared to the more acidic soils at other sites. Redvers also had higher magnesium levels, which the gypsum lowered.

This year, both biochar and gypsum are being tested on peas at Redvers, Swift Current, the Conservation Learning Centre near Prince Albert, Sask., and Lacombe, Alta.

Researchers have measured shoot symptoms and root rot on two different scales, one focusing on symptoms more likely due to aphanomyces, one focusing more on fusarium symptoms, and then nodulation.

At Redvers, there are dramatic differences in plant height from the biochar.

“There wasn’t great nodulation, period, but there was better nodulation in the biochar treated soil, and that was the same in Swift Current and in Lacombe,” she said, as well as Redvers.

However, in Prince Albert, the site with the best nodulation to begin with, the biochar decreased nodulation. That’s likely why overall the research shows no significant effect, Hubbard said.

Shaw said yields in some of the Redvers plots this year will be zero, while those that had the biochar look like they will produce a respectable crop.

“We put the peas on to pea stubble because we’re trying to ensure that there is enough disease that we can pick up differences,” she said.

“On wet years like this, that strategy can work too well.”

The sites also vary in appearance, and it would be hard to guess which plots had the biochar and which didn’t, said Hubbard.

“There’s dramatic difference in how the plots look, but it has nothing to do with the treatments. It just has maybe something to do with the background soil or just chance,” Hubbard said.

The next step involves more soil testing and work in greenhouses to see if results can be replicated.

There is funding to do the project again next year.

“The biochar is very much worth continuing to explore, far more than most other things we’ve tested,” she said.

One variable is that not all biochar is the same because it can come from different feedstock, such as crop residue, wood or any other kind of organic material.

This project used Mayan Gold from Titan Clean Energy at Craik, Sask.

The company recommended this particular formulation because it’s not as powdery and a little easier to work with than some others.

Hubbard said it would be impossible to test all the different types of biochar, so for now they are using a local product that is readily available.

Another factor is the heavy application rate of 10 tonnes per hectare (nearly 9,000 pounds per acre). Biochar is supposed to be stable for a long time, and she said she hopes it could be applied once and last.

At this point it also has to be incorporated into the soil, unless alternative delivery methods are developed. That might concern farmers who don’t till.

“We haven’t tried not incorporating it,” added Shaw.

“We haven’t tried making it into little prills and putting it down in the soil in a fertilizer band.

“But if it looked like it would help with aphanomyces, I think that all the no-tillers would happily go do a little tillage because this is a very thorny problem.”

Shaw and Hubbard both said the work is at early stages and there is far more to do, but the possibility that biochar could lessen root rot impacts by either reducing severity or improving plant growth in its presence looks promising right now.

Funding for the research comes from the Pulse Science Cluster and includes Saskatchewan Pulse Growers, Alberta Pulse Growers, Manitoba Pulse and Soybean Growers and the federal government through the Sustainable Canadian Agricultural Partnership.