Am I wondering about top dressing some Nitrogen on canola to increase yield. When is the right time(growth stage), what form of N works best, weather conditions before, during or after application to avoid leaf burn, rate, does it pay for itself with increased yield most of the time, when is there not a ROI?
Topdressing Nitrogen on Canola to increase yield?
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Canola can respond to fertility boosts pretty late, up to early bloom even. I use plain old ammonium sulfate, but then I usually do not get the sulfur I believe canola needs on at seeding time, so I do it no matter what anyway to get the sulfur on I need, not so much for the n, though the n is a bonus. I used to use a spin spreader, but now our local outlet has a floater which I hire. I usually aim for 25-30 lbs of n, on top of my nh3 at seeding time. I either put it on before seeding, or throw it on as soon as I can afterwards, especially if a good rain is forecast.
IMO, it almost always pays off.
IMO, it almost always pays off.
We don't do a topdress (unless we see deficiency sypmtoms) but have a neigbour with a smaller air cart that puts P and a small amount of starter AMS down at seeding. Then comes in before/after post-emerge spraying (depending on how fast spraying time hits!) and puts on more sulphur. They have floated on AMS before but depending on the year, the big floater tracks can be a big much to deal with. They have also sprayed on liquid 15-0-0-20 as well.
Anyone spraying on 15-0-0-20 with herbicide? Just running some seat-of-pants numbers here, but say you were spraying Liberty. If your carrier was 1/2 water and 1/2 fert (to cut the risk of plant damage), then at 10 gal/ac, you would be applying:
5 usgal water @ 8.3 lb/usgal = 41.5 lbs
5 usgal 15-0-0-20 @ 10.9 lb/usgal = 54.5 lbs
Total = 95.5 lbs/ac
(Obviously would need to adjust that slightly for the density of the Liberty....)
So 95 lb/ac of carrier would be roughly 7 lb of N and 10 lb of S. Not enough for total S needs, but might work if some S was also put on with the seed????
Andrew
Anyone spraying on 15-0-0-20 with herbicide? Just running some seat-of-pants numbers here, but say you were spraying Liberty. If your carrier was 1/2 water and 1/2 fert (to cut the risk of plant damage), then at 10 gal/ac, you would be applying:
5 usgal water @ 8.3 lb/usgal = 41.5 lbs
5 usgal 15-0-0-20 @ 10.9 lb/usgal = 54.5 lbs
Total = 95.5 lbs/ac
(Obviously would need to adjust that slightly for the density of the Liberty....)
So 95 lb/ac of carrier would be roughly 7 lb of N and 10 lb of S. Not enough for total S needs, but might work if some S was also put on with the seed????
Andrew
Why would you be considering this unless you are on highly leachable land? Canola is such a short season crop and it requires N pretty early. I doubt you would see an economic response over just applying it all in the spring. Let alone the risk of not getting it applied if it gets too wet which the odds have been pretty good for lately.
It was more of a question to see if there is a yield response with top dressing N. A way to get more flowers flowering which should then increase yield. We put all of our N on at seeding and are on clay soil.
Maybe the better question is ... Is there a way to increase the amount of flowers that a canola plant will have?
Maybe the better question is ... Is there a way to increase the amount of flowers that a canola plant will have?
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Mommy are you not thinking of boron? Did trials with that last year.... Little to no yield response.
Top dressing N can absolutely help with yield..but many variables need to be sorted prior to application....
IE: what amount of sulphur have you got down?
Are you already in the top "tier" of nitrogen fertilization levels? Hybrid canola vs composite vs polish?
Generally speaking, if you are nitrogen deficient than yes, top dressing will help. However, if you are sulphur deficient than a nitrogen application may not be your best plan of attack.
Rule of thumb is.....2-2.5 lbs N per bushel of yield with a 4-1 nitrogen to sulphur ratio ( in actual lbs nutrient per acre). Some number suggest a ratio of 5 or 6 to 1 but you're already putting down 285$ plus per acre so spend that extra 8$ per acre and bump your sulphur levels. Canola will uptake .5 lbs sulphur per bushel of crop....
Hope this helps...
Top dressing N can absolutely help with yield..but many variables need to be sorted prior to application....
IE: what amount of sulphur have you got down?
Are you already in the top "tier" of nitrogen fertilization levels? Hybrid canola vs composite vs polish?
Generally speaking, if you are nitrogen deficient than yes, top dressing will help. However, if you are sulphur deficient than a nitrogen application may not be your best plan of attack.
Rule of thumb is.....2-2.5 lbs N per bushel of yield with a 4-1 nitrogen to sulphur ratio ( in actual lbs nutrient per acre). Some number suggest a ratio of 5 or 6 to 1 but you're already putting down 285$ plus per acre so spend that extra 8$ per acre and bump your sulphur levels. Canola will uptake .5 lbs sulphur per bushel of crop....
Hope this helps...
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My friend has been doing trials on canola, top dressing with melted urea at podding stage, the last two years he has been seeing from 2 to 4bu increase and the trials he does are all weighed and has multiple side by side trials in the same field
Is that comparing to a check that had the additional n applied at seeding so total N applied is the same? Otherwise all he is proving is that additional N will increase yield.
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Excellent point and I'll bet the answer is no.
That was my original thought too. It would have to be a well planned trial to do it properly.
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It would be nice to hear from the farmers that do top dress. I have been thinking about it also if we get some rain
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