Interpreting soil tests, interviewing agronomists, and fertilizing in fall — LIVE! Q&A with Ross McKenzie


It’s the last day of September, and we figured we’d end it off with a bang! Today’s guest on RealAg LIVE! is really live in studio with host Shaun Haney — Dr. Ross McKenzie.

McKenzie is a retired researcher and soil scientist with Alberta Agriculture and Forestry, and one of the original go-to’s when Haney first started RealAgriculture. Check out the lively Q & A below, where the duo talk about soil testing, nutrient planning, and much more.

Don’t miss the RealAg LIVE! segment most Tuesday, Wednesday, Thursday afternoons at 1 pm Mountain/3 pm Eastern on your favourite social media platform — Facebook, Twitter, YouTube or Twitch!


  • Soil testing season is here.
  • Before we can make any decision on fertilizer, we need the full information of what is in the ground
  • There’s so many variable soil types across the country — you can’t take shortcuts, know what is best for your field.
  • What depths do you want to be sampling at? How many should you be taking? McKenzie says more is better. You can never have too many soil samples!
  • Timing of sampling — the very best time is as close to when you are going to fertilize/seed as possible. But that’s not usually practical, so late fall is adequate. There is such a thing as doing it too soon, as nutrient levels can change depending on fall conditions.
  • McKenzie is a big fan of riding along with the soil sampler. You get to learn very quickly what sort of variability you have in your soil across your field.
  • What should we be testing for in these fields? N-P-K-S, but also check for micronutrients every 3-5 years. Macros every year, micros every 3-5.
  • It’s important to use the right soil tests as well. There’s a few different methods you can request. You can ask your agronomist about different types — there’s plenty of research out there.
  • What do you do with the results sheets? How do you interpret them? What is that benchmark? Go back and look at the recommendations that have been developed. For example, in Alberta, you can go to the Alberta Agriculture and Forestry website to see these recommendations.
  • The lab doesn’t know your soil — McKenzie says it’s really up to the farmer (and maybe an agronomist) to develop an action plan.
  • Understanding the WHY of your soil test results is imperative to being successful on your farm. Don’t be afraid to get a second opinion.
  • Harvest in parts of western Canada has been on a good schedule. Fall fertility is not for everyone, but there’s a lot of people that could be taking advantage of it.
  • Can you apply too late? Not really, but there are restrictions on applying manure/fertility in some provinces
  • What about N on snow? No, other than the spring, there could be an opportunity if the frost is out of the ground. But with more than 4″ of snow, the pellet might not necessarily make soil contact.
  • Is anhydrous ammonia really that bad for soil bugs? It is lethal right at contact point, but biology flourishes again with nitrogen in a warm, moist soil.
  • Variable rate fertilizer: definitely a fan of targeted variable rate, even from well back in the ’80s. But! Is your soil and topography variable enough to make paying for the technology worth it?
  • How well trained is the precision agronomist offering the service and technology? Just yield or satellite images are not enough.
  • New technologies coming down the pipeline: micro-sulphur work with elemental sulphur.
  • Leaf uptake (foliar) vs soil? Remember that plant roots are designed to take up nutrients, leaves are designed to take in carbon dioxide and give off oxygen. In some emergencies, some foliar sprays will correct a deficiencies.

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RealAg LIVE! (view all)Season 1 (2020) Episode 53

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