The Agronomists, Ep 24: Deb Campbell and Don Flaten on 4R nutrient strategy

(Kara Oosterhuis/RealAgriculture)

The right source, right rate, right time, right place for nutrients adds up to more efficient use of fertilizer dollars, and keeps nutrients in the fields and out of our water and air.

On this episode of The Agronomists, host Lyndsey Smith is joined by Don Flaten, recently retired professor of soil fertility at University of Manitoba, and Deb Campbell, agronomist and founder of Agronomy Advantage just north of Guelph, Ont., to cover what 4R nutrient stewardship looks like in action.

Catch a new episode of The Agronomists every Monday night at 8 pm E!


  • Nitrogen and phosphorus! Nitrogen hogs the spotlight sometimes, so Lyndsey will try her best to give phosphorus a turn.
  • Why does 4R Nutrient Stewardship apply more to N and P? Cost. Most limiting nutrients in crop production
  • 4R is a management system where we take a wholistic view of using nutrients
  • Environmental, Economic, Social impacts
  • N and P move through soil differently. Traditionally, P is thought of as immobile in soil, but it does move. It has a large environmental impact when it runs off soil into water. It can leach and get into a tile drain and get into waterways that way. 50 ppb or less can cause algal bloom. “Agronomically insignificant losses that cause big water quality problems”
  • Clip 1: Canola School: Closing the hole in the phosphorus cycle
  • Special designation from Certified Crop Advisers is well received in Ontario, says Deb
  • Biosolids. Push back from neighbours, townships, counties? There’s a full commercial trade for waste products, which are getting further processing and has a fertilizer designation from CFIA. High in organic matter
  • At one time potato farmers who grew oats as a rotation were encouraged to remove the oat straw. That C and N content of the straw needs to be in the right ratio to be broken down by soil microbial activity
  • Clip 2: Corn School: Cold and wet means less available nitrogen
  • Ontario, end of May, early June, continuous release of N as microbes mineralize organic matter, soil testing can benchmark how much N needs to be applied
  • Breakdown of organic matter: N APPEARING! Up to 200 lb of N mineralized during the growing season. Highly variable rates of mineralization
  • More movement to split apps for corn, spring wheat, and even canola
  • Planning P is usually a longer-term plan. How to balance P management for minimal loss, but making sure the nutrient is available when the plant needs it. The form of P, timing of P… ya know the 4Rs!
  • When Lyndsey thinks P in Manitoba, she thinks of hog manure. But P also needs to be planned in Manitoba. In a western context, how are we managing P?
  • Clip 3: Switch up your fertilizer routine with deep banding
  • Deep-banding. How deep? How far apart? Do we still need to rely on other application methods?
  • For full-on zero-tillers, stratification of nutrients? Stratification is a natural process. High root-density in order to take up nutrients. P levels get enriched, which leads to a potential for run-off
  • What keeps Don up at night? Teaching university courses online.
  • Deb’s a fan of strip-till: good combo of minimizing tillage, optimizing fertilizer placement, upping yields. It’s a win environmentally, agronomically. More and more producers are adopting the practice.
  • Over the last… X number of years since Don graduated, there’s been massive improvements in soil health and fertilizer management. Tremendous increases in productivity. Challenging situations for nutrient management, but that means collaboration with equipment manufacturers
  • The evolution in 4R: the farmers, practitioners, agronomists, retailers, must take credit.

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