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Fertilizing canola in Minnesota

Quick facts

  • The canola crop has become an important part of the crop rotations in northern Minnesota.
  • Yields have increased as improved management practices are adopted by growers.
  • Improved fertilizer management is one major contributor to improved yields.

Nitrogen guidelines

Nitrogen (N) fertilizer guidelines can be based either on the results of the soil NO3--N test or the consideration of expected yield, previous crop, and soil organic matter content. The soil NO3--N test is appropriate for western Minnesota

When the soil NO3--N test is used the N guidelines can be derived from the following equation:

Nitrogen fertilizer formula

Suggested N in lb./acre = (6.5) (EY) - STN(0-24 in.) Npc

Nitrogen formula variables

  • EY = expected yield (lb./acre)
  • STN = nitrate-nitrogen (NO --N) measured to a depth of 24 in. (lb./acre)
  • Npc = amount of N supplied by the previous legume crop (lb./acre).¬†These N credits are summarized in table 6.

Nitrogen guidelines in the first table are for canola in situations when the soil NO3--N test is not used based on expected yield of the crop in pounds per acre.

Nitrogen guidelines

Crop grown last year Organic matter level* 10-15 lb./acre yield 16-20 lb./acre yield 21-25 lb./acre yield 25+ lb./acre yield
Alfalfa (4+ plants/ft2) Low 0 lb. N/acre 0 lb./ N/acre 0 lb. N/acre 0 lb. N/acre
Alfalfa (4+ plants/ft2) Medium/High 0 0 0 0
Alfalfa (23 plants/ft2) Low 0 0 0 0
Alfalfa (23 plants/ft2) Medium/High 0 0 0 0
Soybeans or alfalfa (1 or less plants/ft2) Low 0 10 20 30
Soybeans or alfalfa (1 or less plants/ft2) Medium/High 0 0 0 0
Group 1 Crops Low 0 0 0 0
Group 1 Crops Medium/High 0 0 0 0
Group 2 Crops Low 40 50 60 70
Group 2 Crops Medium/High 20 30 40 50
  • Low = less than 3.0%; medium/high = 3.0% or more.
  • Crops in Group 1: Alsike clover, birdsfoot trefoil, grass/legume hay, grass legume pasture, fallow, red clover.
  • Crops in Group 2: Barley, buckwheat, canola, corn, grass hay, grass pasture, oat, potato, rye, sorghum-sudan, sugar beet, sunflower, sweet corn, triticale, wheat.

Phosphate and potash guidelines

The listed rates are suggested for a broadcast application.

Phosphate fertilizer guidelines (pounds of P2O5 suggested to apply per acre) for canola production are based on either the Bray-P1 or Olsen soil methods test and reported in parts per million (ppm).

Use one of the following equations if a phosphate guideline for a specific soil test and a specific expected yield is desired:

  • P2O5 rec = [3.60 (0.17) (Bray P, ppm)] (Expected yield)
  • P2O5 rec = [3.60 (0.22) (Olsen P, ppm)] (Expected yield)

Phosphate guidelines

Expected Yield Bray-P1
Expected Yield Olsen
0-5 ppm
0-3 ppm
6-10 ppm
4-7 ppm
11-15 ppm
8-11 ppm
16-20 ppm
12-15 ppm
21+ ppm
16+ ppm
1015 cwt./acre 40 lb./acre 25 lb./acre 15 lb./acre 0 lb./acre 0 lb./acre
1620 cwt./acre 55 40 25 0 0
2125 cwt./acre 75 50 30 10 0
25+ cwt./acre 80 55 35 10 0

Potash fertilizer guidelines (pounds of K2O suggested to apply per acre) for canola production are based on the ammonium acetate potassium test reported in parts per million (ppm).

Use the following equation if a potash guideline for a specific soil test and a specific expected yield is desired:

  • K2O rec = [0.0358 (0.023) (Soil Test K, ppm)] (Expected yield)

Potash guidelines

Expected Yield 0-40 ppm 40-80 ppm 80-120 ppm 120-160 ppm 160+ ppm
1015 cwt./acre 60 lb./acre 40 lb./acre 25 lb./acre 0 lb./acre 0 lb./acre
1620 cwt./acre 85 60 35 10 0
2125 cwt./acre 110 80 45 15 0
25+ cwt./acre 115 85 50 15 0

Sulfur guidelines

The canola crop is very responsive to sulfur fertilization. When this crop is grown on heavy textured soils, a rate of 10 to 15 pounds of sulfur per acre is suggested. The suggested rate increases to 20 to 30 pounds of sulfur per acre when this crop is grown on sandy soils. Broadcast applications are appropriate for this crop.

Other nutrients

There is no research data to suggest that other nutrients are needed in a fertilizer program for canola production. Therefore, none are recommended.

CAUTION: Do not apply fertilizer in contact with the seed at planting.

Authors: Daniel E. Kaiser, Extension nutrient management specialist, and Keith Piotrowski, director of the University of Minnesota soil testing laboratory

Reviewed in 2023

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