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Canola Nitrogen Rate Trial

Research Question: Are nitrogen (N) rates being used on canola across Manitoba sufficient for optimizing yield and nitrogen efficiency?

Treatments

  1. Reduced N Rate (75%)
  2. Standard N Rate (100%) – Farm Normal for Field
  3. High N Rate (125%)

Trial Setup: Randomized complete block, each treatment was one equipment width x field length, with four replicates per location (12 strips per location)

Data Collection: Plant Counts, Tissue N (bolting), Yield, Protein, Oil Content

Click here to see full protocol.

Trial Results to Date: 

Summary of 2022 – 2023 Trial Results

Click the Trial ID in the table below to view the full site report.

Trial ID (year) RMStandard N Rate (100%)Reduced
N Rate (75%)
High
N Rate (125%)
CV
N Applied
(soil residual N)
YieldChange in Yield from Standard Rate
lbs. N/acbu/acbu/acbu/ac%
NR_01 (2022)Swan Valley West113 (76)47.1-0.4+1.61.8
NR_02 (2022)Macdonald122 (55)52.0+2.3+3.9*4.1
NR_03 (2022)Lorne138 (60)35.4+0.9+0.15.5
NR_04 (2022)Morris120 (53)58.6-4.2*+0.44.5
NR_05 (2022)Two Borders118 (79)42.0-3.3+0.911.9
NR_06 (2023)Minitonas-Bowsman113 (18)55.5-5.3*-0.55.2
NR_08 (2023)North Norfolk135 (25)58.0-2.5+4.29.2
NR_09 (2023)Brokenhead137 (30)61.7-0.9+3.04.2
NR_10 (2023)Two Borders130 (50)51.4+2.3+3.37.6
NR_11 (2023)De Salaberry158 (127)22.8-1.3-0.15.5
COMBINED129 (57)48.4-1.3+1.6*24
* indicates significant difference in treatments with p < 0.05

Grain Yield

  • Average grain yield across all trial locations when the farm normal rate of N fertilizer was applied was 48 bu/ac, ranging from 23 – 62 bu/ac.
  • Overall, there was a significant 1.6 bu/ac increase in yield when an additional 25% N fertilizer was applied to the farm standard N rate.
  • Two of 10 locations had a significant yield reduction of -4.2 and -5.3 bu/ac when N was reduced by 25%.
  • One of 10 locations had a significant yield increase of 3.9 bu/ac when N fertilizer was increased by 25%.

 Nitrogen Fertilizer Efficiency

  • The current N fertilization recommendation for canola in Manitoba is to provide canola with 2.5 to 3.5 lbs. N (soil + fertilizer) per bushel of yield targeted (Canola Council of Canada and Manitoba Agriculture). Example: for a target yield of 50 bu/ac recommended N would be from 125 to 175 lbs. N/ac (soil + fertilizer).
  • N provided to the crop per bushel at farm standard N rate ranged from 2.4 to 5.6 in this trial.
  • As the amount of fertilizer supplied to the crop increases the efficiency of N was reduced → more N used per bushel of yield.

Economic considerations will vary farm-to-farm depending on buying price of N fertilizer, canola price and standard N rates.

 In Summary

  • All results presented are preliminary as this trial will continue in 2024 and 2025 field seasons.
  • Farms that saw a decrease in yield with reduced N rates achieved high grain yield (>55bu/ac) with modest N fertilization (2.4 and 2.9 lbs. N/bu yield).
  • The significant combined increase in grain yield of 1.6 bu/ac for could be sufficient to cover the added cost of 32 lbs. N/ac ($0.76 lbs. N and $16 canola).

Funded in part by the Governments of Canada and Manitoba under the Sustainable Canadian Agricultural Partnership, a federal-provincial-territorial initiative.