Wheat Pete's Word, April 17: Minding the P and K questions


It’s time for Episode B of the mid-April Wheat Pete’s Word!

(Check out Episode A here)

On this episode, host Peter “Wheat Pete” Johnson focuses on soil nutrients, specifically phosphorus and potassium (potash, K). And hey, there’s even a great explanation of how to put more fertilizer down at seeding without endangering the seed — thanks, Western Canada!

Have a question you’d like Johnson to address or some yield results to send in? Disagree with something he’s said? Leave him a message at 1-888-746-3311, send him a tweet (@wheatpete), or email him at [email protected].


  • Looking at soil with a range of phosphorous — form four to 12 Olson test (quite low, to low). Same test has potassium (K) from 300 to 570. Wow! Ontario wishes they had those kinds of K levels.
  • A 10″ disc-drill with a mid-row band. What’s a mid-row band? In a dry fertilizer set up, it splits the distance between openers and allows a producer to put more N down at seeding, safely.
  • Is there a benefit to putting phosphorus, mid-row to get better soybean yields? But they’ve been told, soils are higher calcium and magnesium, and that ties up P quickly. Well, yes, it’ll get tied up as calcium phosphate. Banding it means you limit soil interaction and all of it doesn’t get tied up all at once. Either way, yes, phosphorus with the beans.
  • Older research, looking at potash (k) on 7.5″ spacing and did a “mid-row” band on 15″ soybeans, and there wasn’t a benefit. It was just too far away. So, then looked at 3″ apart and yes, that worked, as did broadcast K.
  • Is 5″ away from the seed row with P too far? Do a trial. What about broadcast P in the spring a better bet vs. too far away?
  • How long does it take for spring-applied K (potash) to be in a form the plant takes up? Immediately! Put it on before, or three weeks after planting, or at the first flower – it’ll get there with some moisture, and we don’t lose it, except in sandy soils (with low CEC).
  • A farmer has corn, oat/pea mix, alfalfa/timothy hay rotation. In that, would boron, zinc, and S in starter on corn make a difference? Do some trials. S is often needed, but zinc and boron are required in much lower amounts. Zinc deficiency can happen in corn, for sure. If you’ve got manure in
  • New farm, been in pasture forever, P at 6 (low) K at 113 (170 is solid). Grow edibles, of course! Now, you also want to build that soil test. Do you apply fertility after working the field or before (it’s being tiled). If it’s too deep, it’s too hard for the roots to find it. So broadcast after working the ground. I might even slather on some P ahead of plowing.
  • Manitoba rotation question. Grew rye as a grain crop last year. Didn’t harvest the straw. And many say that the crop following rye doesn’t do well (and that helps with weed control, but also can impact crops). Will it impact soybeans? Likely less so than other crops.

Wake up with RealAgriculture

Subscribe to our daily newsletters to keep you up-to-date with our latest coverage every morning.

Wake up with RealAgriculture

Other Episodes

Wheat Pete's Word (view all)Season 6 (2020) Episode 37

Please register to read and comment.


Register for a RealAgriculture account to manage your Shortcut menu instead of the default.