Dr. Tandra Fraser
AAFC Charlottetown
Digging Deep Into the Soil
It may be just a handful of dirt to most people, but to Dr. Tandra Fraser it is a thriving ecosystem– one that has the potential to impact the bottom line for the grains and oilseeds producers across the Maritimes.
A soil microbiologist with Agriculture and Agri-Food Canada (AAFC), Dr. Fraser, is conducting research projects on the soybean nodulation in low pH soil and biostimulants in corn and wheat with the Atlantic Grains Council. Both the trials are centered at the (AAFC) Harrington Research Farm near Charlottetown, Prince Edward Island.
While biostimulants are growing in use among producers to help improve nutrient absorption or mitigate plant stress, she explained they are not regulated in the same way as pesticides. She added there has been little in the way of testing regarding the efficacy of biostimulants for corn and wheat, especially when it comes to growing conditions in the region.
“We need research that is geared to conditions in Atlantic Canada,” she explained. “A biostimulant may not act the same way on Prince Edward Island or in New Brunswick as it does on the Prairies.
The four-year project tests a variety of products at both the recommended fertilizer rate and reduced nitrogen calculation that is 70 per cent of the recommended total. There is a control application where no treatment is added.
The products include a seaweed extract and two others that are promoted to contain bacteria that can fix atmospheric nitrogen and supply N to the plant through the roots and leaves.
The trial entered its third year in 2025, while the results to date showed virtually no effect on yield from any of the biostimulants compared to the control sample at any of the N application rates. While she said that was somewhat of a surprise, Dr. Fraser and her team are still assessing the nutrient uptake of the plants and the potential carryover of the effects into the next crop year.
“This year we added an additional in-furrow application so we are interested to see if that will show any different results,” she said.
As soybeans require a large supply of nitrogen over the growing season to optimize both yield and protein content, inoculating soybeans can help the plant form nodules that can draw nitrogen from the atmosphere. Producers often also apply supplemental nitrogen, which means added costs and greenhouse gas emissions.
Dr. Fraser and her team are looking at ways to maximize nitrogen use efficiency. Previous research has shown factors such as high nitrogen levels in the soil or low pH can slow down nodule development and reduce nitrogen fixation and supply to the plant.
She explained that most soybean trials conducted in the region seek to maximize yields under optimal pH conditions using some supplemental nitrogen fertilizer. This project, which began in 2024, compares four conventional and four Roundup Ready varieties. Test plots were established with and without nitrogen in the soil with a pH of 5.5 or 6.5. They were compared for nitrogen levels in the soil, nodule development, nitrogen uptake and yield.
Results from the first year indicated there was a decrease in the number of nodules and weight in soils with nitrogen fertilizer but there was little difference between the varieties. Samples were also collected from 12 sites on Prince Edward Island from the Yield Enhancement Network to assess nodulation and nitrogen uptake in commercial fields.
“We plan to expand the number of trials over the next three years so we can evaluate the range of soil pH levels with and without inoculation,” Dr. Fraser explained. “The goal is to get a better understanding of the relationship between soil pH, available nitrogen and plant uptake, and how that will impact yields for commercial growers.”
