Getting the dirt on 4R nutrient stewardship

Fertilizer Canada’s 4R nutrient stewardship research tour delivers valuable information

In the ever-changing world of farming, information is a more valuable commodity than the finest canola crop. Consequently, the recently launched webinar series “Across Canada Tour of 4R Nutrient Stewardship Research” sponsored by Fertilizer Canada is must-see viewing.

The tour began last month in Alberta, where co-presenter Dr. Miles Dyck offered an overview of 4R Nutrient Stewardship research in Alberta.

As an associate professor of soil science in the Department of Renewable Resources at the University of Alberta, Dyck was a natural choice due to his involvement with the university’s Breton Plots. The long-term research plots are used to study the impact of agriculture management on soil properties and processes.

For Dyck, the timing of this tour couldn’t be better. “Agriculture today faces considerable scrutiny around its environmental footprint,” said Dyck. “Fertilizer in particular is often under the microscope, especially in connection with greenhouse gas emissions from soil following fertilizer application.”

The 4R Program, which stands for right rate of nutrient fertilizer, right placement, right timing of application and right product for the application or crop, seeks a “win-win” for farmers and industry.

“The idea is to increase fertilizer use efficiency by applying it in a way that maximizes its use by the target crops. In that way, we can improve productivity and minimize the environmental impact at the same time.”

As part of his presentation, Dyck highlighted a few key points for participants.

The rules of rotation

“Specifically, our research results have shown that long-term management of crop rotation and fertilizer application has a big impact on the levels of soil nutrient reservoirs. We have noticed that in the treatments where the fertilizer applications of nitrogen, potassium and sulfur match the removals in the harvested portions of the crop, soil quality and crop yield increase while the intensity of greenhouse gas emissions (amount of emissions per kilogram of grain or crop produced) goes down.”

Another interesting point concerned the two long-term rotations being studied by Dyck and his colleagues.

“One is a simple two-year rotation of wheat fallow and the other is a more diverse five-year rotation that includes three years of cereals (wheat, oats and barley) and two years of alfalfa-brome hay.”

When researchers looked at the long-term data from these crops, they found that rotation had a significant effect on how the crops responded to nitrogen fertilizers. For example, the two-year rotation needed 90 kg of nitrogen per hectare (80.3 pounds per acre) to grow a wheat crop with a comparable yield to wheat in the five-year rotation with only 50 kg N/ha (44.6 lbs. N/ac.).

“The biological nitrogen fixation of the alfalfa in the five-year rotation adds a lot of nitrogen and reduces the amount needed for the cereal crops.”

Also emerging from the focus on rotations was the fact that forage crops use a lot of sulfur and potassium, so in the five year rotation the wheat responded to sulfur as much as to nitrogen.

“For wheat to respond to potassium and sulfur fertilizer is rare in western Canada. For producers, the take home message is that rotations have really diversified over the last 20 years and even if you’re not growing a forage crop, you may be growing canola or pulses that also have a high demand for sulfur.”

Record and react

Since research shows that long-term management impacts soil, farmers may want to pay attention and keep records of crops, yields and nutrient applications over time. Results from this research indicate that nutrient deficiencies can emerge after changing crop rotations. Further, addressing P, K and S deficiencies will increase crop nitrogen uptake and nitrogen use efficiency. Using tables on the Alberta Agriculture and Forestry website, or working with an agronomist, producers can take use yield information to estimate nutrient removal from different crops.

Alberta was the first stop on this webinar tour and organizers were pleased by the response, with 68 people taking it in.

About the author

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Geoff Geoff Geddes is a freelance agriculture and business writer based in Edmonton. Find him online at www.thewordwarrior.ca or email [email protected]

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