The Agronomists, Ep 32: Amber Knaggs and Chris Roelands on tissue testing


A tissue test can give you a snapshot into what’s happening in a plant as far as nutrient uptake is concerned. The test doesn’t necessarily predict an issue, and not all results are actionable; that’s left many agronomists wondering how best to use tissue tests in conjunction with soil tests, zone mapping, and fertility planning.

To tackle that discussion, host Lyndsey Smith is joined by Chris Roelands with Honeyland Ag Services, and Amber Knaggs of Croptimistic Technology. From where and when and how to sample a plant, to what deficiencies can be corrected, to how best to work tissue testing into the toolbox, listen on to this episode of The Agronomists!

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


  • New people to the show! This is both our guests’ first time on The Agronomists (so an intro is due)
  • Tissue test report example (good to know what it looks like, what to look for)
  • Sufficiency ranges, balances, ratios. How low is low?
  • Is a plant tissue test proactive or reactive? Knaggs says that it’s reactive, generally. P deficiency in wheat example where the fertilizer did go down, but in a side-band, not seed-placed where it was really deficient. Bummer
  • Reactive and a snapshot of what’s happening in the field
  • Clip #1: Corn School: Hideous cobs? It could be boron deficiency
  • Is the best to pull tissue samples that follow grid/zone soil sampling? Depends what that zone is telling you in the first place
  • Remember, plant physiology and check the lab requisition form for what area of the plant needs to be sampled. For corn: most recent collared leaf, for soybeans and wheat: most recently matured leaf
  • When sampling the most recent collared leaf, where do you sever it?
  • When sampling soybeans, do you cut at the base of the trifoliate and do you include the leaf stem?
  • Some people pull the whole plant! Which is faster, but isn’t needed in the lab, thanks
  • What’s the turn-around test, and are all findings worth taking action on?
  • Let’s take a moment to talk about B, and it’s availability. It can be available, then not available quite quick
  • There are so many things that interact with the crop, including environment, and so much can change with the crop’s fertility throughout the season
  • Clip #2: Soybean School: Managing manganese deficiency
  • If you have good soil tests and a good sampling regimen, doesn’t tissue testing just reflect what the crop could do? Just because there’s a nutrient that should be available in the soil test, doesn’t mean it will get into the crop. Soil isn’t static, and it can be highly variable, so environmental conditions can really affect nutrient availability throughout the season
  • Mn toxicity in canola, interesting case study
  • Sometimes when people look to do tissue testing, they have the sprayer ready like a fighter jet, but not every issue can be solved in-season
  • Does a low reading of a nutrient imply that plant growth or productivity is being limited, or might the calibration of the test be incorrect?
  • “My tissue test is back and I’m deficient in X.” How does an agronomist walk through the decision making process and set the expectations?
  • Don’t be afraid to call in reinforcements!
  • An agronomists favourite response to a question: it depends
  • Two things we’ve learned: be curious, and ask smart people your questions (it pays to have a good team behind you as an agronomist)

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The Agronomists (view all)Season 2 (2021) Episode 20

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