The Agronomists, Ep 66: Christine Brown and Mitchell Timmerman on manure management


There are so many pearls of wisdom in this episode of The Agronomists, such as, sometimes old science is good science; compaction is all bad; and not all manure is created equal.

But how should you pay for manure — by the pit or by the load? How much is it worth? Is fall-applied with cover crop seed OK, or do you wait? So many questions.

For this episode on valuing manure and determining how best to use this delightful soil amendment in crop production, host Lyndsey Smith is joined by Christine Brown, of the Ontario Ministry of Agriculture, Food and Rural Affairs, and Mitchell Timmerman, with Manitoba Agriculture.



  • It’s Lyndsey’s birthday and she chose to talk poop, as one does
  • Parts of Manitoba are still under water right now; there’s no field work happening
  • Ontario, however, is rolling — though perhaps a little slowly
  • Let’s talk manure!
  • Frozen ground is a nitrogen stabilizer. So, good for you Manitoba!
  • Manitoba has a no-manure rule from Nov 10 to April 10, with a mechanism for moving those dates if conditions require it
  • Ontario does not have such rules — check with your province
  • Christine reminds us: applying manure as close to when the crop need the nutrients is best, but that’s also very tricky
  • Fall application of manure is still most common in Ontario. Incorporation and a “trap crop,” ie. a growing cover crop helps minimize losses
  • Losses are an environmental consideration, but it’s also an economic one, to the tune of over $100/ac
  • Compaction is always a risk — application timing will always depend on soil conditions
  • How much is manure worth? Example: liquid manure from a 2,000 finisher hog set up ends up at about $80,000 worth of crop-available nutrients, plus microbiology and carbon
  • The key is, how do you make the most of those nutrients? It’s hard math if using nitrogen as the driver (too unpredictable)
  • But, the P and K add up to about $125/ac as applied (Thanks, Peter Johnson for the math)
  • Is there a volume maximum per acre?
  • If you’re buying manure, should you buy the whole tank to even out the water differences between loads?
  • Old science can still be good science (we stand on the shoulders of giants)
  • Manure isn’t just about an immediate N source (replacement for commercial N), it can also be an N enhancer, or a long-term play on building soil health
  • Phosphorus component can be the driver of going the distance (by rule or by need)
  • Biology additions are much harder to quantify and value
  • We still like to see results — like a thick, green crop
  • Strike the balance between good for the water, good for the soil, good for the crop (that might mean using some horsepower)
  • How much liquid manure can go on per acre? Depends on the soil type and conditions
  • The legacy of manure nutrients: Dr. Don Flaten talked about this in a past episode (*you can see it here)
  • Tl:Dr? We have perhaps overestimated the immediate nutrient availability and underestimated the long-term benefits of a manure program on a particular field
  • Ideal timing of manure will depend on the manure type and which crop will be growing next, Christine says
  • After wheat, is it better to incorporate manure along with cover crop seed, or drill in the seed and let cover crop grow and spread on top in late fall?
  • For those under saturated conditions right now, is some of the N lost already, from fall-applied fertilizer and/or manure? Mitch’s turn to say, it depends.
  • Liquid manure in early spring on a fall-seeded crop can cause burn. Will the nutrients be available, though, is the question
  • At this point, Lyndsey realizes she’s not getting to the clips. Sorry, Producer Jay
  • Is precision-applied manure a reality? Yes, and no. Choosing the right field is a step in that direction. Christine says there is work being done where commercial N is applied in concert with manure
  • There’s no feasible way to meet all of the corn crop’s N needs with manure
  • Mitchell has volunteered to test every load of manure that leaves the pit, maybe
  • Get those manure purchase agreements nailed down. Agitate that pit!
  • Looking at digestate and availability shows there can be huge value differences base on practice/timing (hello 4Rs!)
  • Is there a scale of best to worst manure? Well, there IS a range of C:N ratios, nutrient density, and nutrient availability. The more bedding, the more tie-up will occur (but the more carbon added to the soil)
  • Chicken manure is almost gold. Cherish it.


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