Wheat Pete's Word, Mar 29: Green up, setting up on-farm tests, melting urea and sulphur decisions


Purple wheat, especially at this time of year, is not anything that can be fixed, unless you can manage to change the weather to warm up in a hurry.

Spring warm up is a big focus of this week’s edition of Wheat Pete’s Word — from making the call on clover additions, to early S and N decisions, and on to making the call on “rescue” treatments, host Peter Johnson answers your questions and concerns happening this last week of March.

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].


  • For Ontario, we likely have full moisture recharge, over the winter since the really dry year/fall of 2022 (not Western Canada dry, but dry by Ontario standards)
  • Josh in Chatham-Kent is already planting potatoes!
  • Shout out to the women in agriculture — the change in the gender balance in agriculture programs is to be celebrated!
  • How many seed compartments inside of an apple?
  • Pete’s getting on the podcast train. He listened to Neil deGrasse Tyson who likens climate change and action to peeing in a pool
  • When it comes to greenhouse gasses, imagine if it changed colour if you peed in the pool! Yeah, that would change the way people people acted, wouldn’t it?
  • Please note: there’s been an incredible maple syrup crop this year. Many pulled taps this weekend (editor’s note: it’s still rolling in the east, but that’s to be expected)
  • Ben Rosser, corn specialist with the Ontario Ministry of Agriculture and Food is putting together a list of plot protocols for the Thames Valley region, for Ontario Soil and Crop projects
  • Got ideas? Get the script written. Pick the project, get the product in place, be ready to go so that when it comes time to do it, it doesn’t take any time.
  • Is it too late for red clover? It’s the end of March. Not too late, at all. Even April can work
  • Be cognizant of compaction with drag hose manure
  • For clover, in past trials, March was the best, February and wasn’t far behind, but April was still really good
  • December isn’t great, though, FYI
  • When should we expect green up? We want seven days of the average temperature above zero Celsius. So the average is the high plus the low divided by two
  • For those tempted to get out there and put some ammonium sulfate on my wheat crop. One grower says 150 pounds of ammonium sulfate. Wait! Why so much? That’s 36 pounds of sulphur. We do not need 36 pounds of sulphur
  • The demand for nitrogen of the wheat crop early  is really small. We don’t get into significant nitrogen demand until we hit the stem elongation, growth stage 30. It’s likely going to be at least the 20th of April maybe even later than that before we get to growth stage 30
  • Do a test strip
  • Sulphur demand in wheat is totally different than sulphur demand in corn
  • Wheat plant takes up 90% of its sulphur by the time it hits anthesis, by the time it heads out. Conversely, corn only takes up 55% of its sulphur by the time it tassels
  • Check out the Agronomists on sulphur
  • I like split nitrogen because it lets me do a better job of predicting my nitrogen rate
  • Be very careful when you look at the analysis of fertilizer!
  • In North America, when we report fertilizer values, nitrogen is pounds of actual nitrogen. Phosphorus is not pounds of actual phosphorus. It’s pounds of P205. Potash is K2O, sulphur is pounds of actual S
  • Sulphur vs. sulphate – divide by three
  • If you buy dry ammonium sulfate 21-0-0-24 That’s 21 pounds of nitrogen per 100 pounds. It’s 24 pounds of sulfate per 100 pounds. And so when you look at that sulphate number divide by three
  • What about applying dissolved urea or “melted” urea call it, can you decrease N rate by two thirds because that foliar applied melted urea is just so much more efficient? Well, at least 50% nitrogen utilization in a cereal crop or a corn crop. It’s very rare we get less than 50%. If you look at the yen data in winter wheat are often at two thirds or 70%. nitrogen use efficiency sometimes higher
  • If protein is one sixth nitrogen, even if the melted urea was 100% efficient, which is not, there’s no way you could cut back by two-thirds
  • Remember roots are designed to take up nitrogen, leaves are not
  • There is some research that suggests that when we put that foliar nitrogen on that melted urea, 90% of it is taken up by the roots, because the rain comes, washes it off the leaf, it goes into the soil and gets taken up by the roots
  • Wheat went in on October the 25th, which is a tad late in Michigan
  • The big demand for phosphorus in wheat that really we get a yield boost from comes in the fall
  • But if you have a low soil test, could you get a response to spring phosphorus? Probably a small response
  • How fast can you build up soil tests? So salt concentration becomes a significant issue
  • Most of the time, if you build over 10 years, then you’re going to get big fertilizer responses as you apply those broadcast fertilizers to build that soil test
  • There was a comment on Twitter that purple wheat, it means phosphorus and it needs zinc. Malarkey! When it’s cold, the roots can’t grow, and with a big plant above and the temperatures are above zero it photosyntheses and it’s got nowhere to send the energy and so it turns into anthocyanin
  • Purple wheat means that you’ve crappy root growth because the soil is cold and that’s all

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