Soil fertility specialists from the University of Manitoba brought the latest “4R” research to the public while keeping a healthy distance, thanks to an innovative self-guided field tour July 23-25 near Carman.
“The beauty of a self-guided tour is that people can do it at their leisure,” soil ecology professor, Mario Tenuta told the Manitoba Co-operator prior to the event. “This got me thinking this (format) could actually be beneficial instead of a drawback because of COVID(-19).”
Why it matters: The jointly held self-guided tour, which relied on QR codes to access video and background on nitrogen efficiency research in corn, is one of several ag events using technology to get back to business safely.
The tour was a joint initiative between the University of Manitoba, province and 4R Industrial Research Chair program.
In a wide aisle between research plots, participants proceeded through numbered stations where they could scan a QR code (or quick response code) with their smartphone. The bar code-like image would then link the visitor to research information or video of one of the researchers presenting work on various topics of nitrogen application and the four “Rs” of nutrient stewardship (right source, right rate, right time, right place).
“The aims of the projects now are to increase nitrogen use efficiency of grain corn,” Tenuta said in a video overview of the site. “That’s to meet national objectives of reducing greenhouse gases and other nitrogen losses to the environment.”
The site is one of three in a project spread across Manitoba, Ontario and Quebec.
Don Flaten, also of the University of Manitoba, presented on attempts to measure nitrogen mineralization from soil organic matter.
In his video, he pointed to research trials by provincial soil fertility specialist John Heard, which measured up to 150 pounds per acre (lbs./ac.) of nitrogen solely from mineralization. University of Manitoba researcher Lanny Gardiner has measured anywhere from 15-90 lbs./ac.
“This could make quite a difference for a farmer’s pocketbook and also our environmental footprint if we could predict the amount of nitrogen mineralization from some sort of soil test,” Flaten said.
Unfortunately, of Gardiner’s 10 testing methods, “None of them worked worth a darn,” Flaten said.
He added breakdown of soil organic matter is somewhat dependent on soil moisture and weather, making it very hard to predict.
He suggested producers keep a close eye on residual nitrogen through soil testing each year so they can gauge if their application plan is working.
Tenuta presented research measuring the greenhouse gas nitrous oxide (N2O) produced in the soil from transformation of nitrogen from fertilizer, manure and crop residues.
“We need nitrogen,” he said, but most nitrous oxide gas from human activity comes from agriculture.
Research is showing that 4R practice can significantly affect how much N2O gas is produced. For instance, Tenuta said, in-season applied nitrogen seems to produce more of the gas than fertilizer applied at planting, possibly because higher temperatures cause faster nitrification.
Surface dribble caused more N20 gas than side banding. Adding a nitrification inhibitor, meanwhile, reduced N20 gas by about two-thirds.
Gardiner spoke about studies on nitrogen application timing. He used two different applications – fertilizer applied up front, broadcasted and incorporated in various amounts, or 30 lbs./ac. side banded at planting and then topped up (at different amounts) at the V4 or V5 stage.
The study showed differences between the timings in only three out of 17 sites, Gardiner said. He found reduced yield potential in the plots where the top-up was delayed after nitrogen deficiencies began to show.
Gardiner said that while he doesn’t expect a yield increase or a reduction in the amount of nitrogen needed if in-season application is used, in-season application is an important tool. It could allow producers to evaluate crops before deciding on a final rate of nitrogen application, or to add nitrogen if they see an increased yield potential, he said.
These results are consistent with American studies, Gardiner added.
Matt Gervais, technician with the University of Manitoba’s Applied Soil Ecology Lab, demonstrated (in video) using hand-held, tractor-mounted or drone-mounted spectral sensors to measure how much nitrogen corn plants are absorbing.
The principle is that light reflected off the leaves will come back at different intensities depending on what the plant is taking in, Gervais said. The V4 and V8 stages give the best indication of corn’s nitrogen uptake at a time when it might be viable to add more nitrogen to the crop.
Various trials at the site used in-season nitrogen application. The researchers had three examples of “Y-drops,” attachments for high-clearance sprayers to get applications below the corn canopy. One example was Y-DROP brand, and two were built by producers out of metal tubing and hoses.
At the time of writing, tour videos were still available online at soilecology.ca.