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Fertilizing oat in Minnesota

In Minnesota, the oat crop is used for either grain and straw or as a nurse crop for seeding legumes. The recommendations in the tables that follow are intended for situations where the crop is grown for grain and straw.

Nitrogen guidelines

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

When the soil nitrate test is used, the fertilizer N guidelines are calculated as follows.

  • Suggested N in lb/acre = (1.3) (EY) - STN(0-24 in.) - Npc

Nitrogen formula variables

  • EY = expected yield (lb/acre)
  • STN = nitrate-nitrogen (NO3--N) measured to a depth of 24 in. (lb/acre)
  • Npc = amount of N supplied by the previous legume crop (lb/acre).

Nitrogen, when needed, can be supplied from several sources. If applied in a way to prevent loss, all sources of nitrogen have an equal effect on yield. When using either dry or liquid sources, the fertilizer N can be broadcast and incorporated before planting. If anhydrous ammonia is the preferred source, this N fertilizer can be knifed in before planting.

Nitrogen guidelines for oat*

Crop grown last year Organic matter level** 40-60 bu/acre 61-80 bu/acre 81-100 bu/acre 101-120 bu/acre 120+ bu/acre
Alfalfa (4+ plants/ft2) Low 0 lb N/acre 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 0
Alfalfa (2-3 plants/ft2) Medium/High 0 0 20 40 60
Alfalfa (2-3 plants/ft2) Medium/High 0 0 10 30 50
Soybeans or alfalfa (1 or less plants/ft2) Low 0 20 40 60 80
Soybeans or alfalfa (1 or less plants/ft2) Medium/High 0 0 30 50 70
Edible beans, field peas Low 20 40 60 80 100
Edible beans, field peas Medium/High 10 30 50 70 90
Group 1 Crops Low 0 0 0 25 45
Group 1 Crops Medium/High 0 0 0 15 35
Group 2 Crops Low 40 60 80 100 120
Group 2 Crops Medium/High 30 50 70 90 110

*Use this table in situations when the soil NO3--N test is not used based on expected yield of the crop in bushels per acre.

**low = less than 3.0%; medium and 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.

Suggested nitrogen credits for various crops that might precede wheat in a crop rotation*

Previous crop First year N credit (lb N/acre)
Soybean 20
Edible beans, field peas 10
Harvested sweet clover 10
Harvested alfalfa** or non-harvested sweet clover
4-5 plants/ft2 75
2-3 plants/ft2 50
1-2 plants/ft2 25
1 or fewer plants/ft2 0
Harvested red clover 35
Sugar beet
Yellow leaves at harvest 0
Light-green leaves at harvest 15-30
Dark-green leaves at harvest 60-80

*Use these credits when the soil nitrate test is used.

**If 3rd or 4th cutting was not harvested, add 20 lb. N/acre to the N credits listed.

Suggested nitrogen credits when wheat is grown 2 years after a legume crop

Previous legume crop Second year N credit (lb N/acre)
Alfalfa (4+ plants/ft2) 35
Non-harvested sweet clover 35
Alfalfa (2-3 plants/ft2) 25
Birdsfoot trefoil 25
Red clover 20

Phosphate and potash guidelines

The rates listed are appropriate for both broadcast and banded (drill applied) application. There is no research evidence with this crop to suggest that the banded placement is more efficient than a broadcast application.

Caution

  • Do not apply more than 20 lb. N per acre as urea (46-0-0) with the drill.
  • Do not place ammonium thiosulfate (12-0-0- 26) in direct contact with the seed.
  • Do not place fertilizers containing boron in direct contact with the seed.

Phosphate fertilizer 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
40-60 bu/acre 30 lb/acre 20 lb/acre 10 lb/acre 0 lb/acre 0 lb/acre
61-80 bu/acre 40 30 15 0 0
81-100 bu/acre 50 35 20 0 0
101-120 bu/acre 60 45 25 10 0
121+ bu/acre 70 50 30 10 0

*Pounds of P2O5 suggested to apply per acre for oat production based on either the Bray-P1 or Olsen soil methods test 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 = [0.644 - (0.032) (Bray P, ppm)] (Expected Yield)
  • P2O5 rec = [0.644 - (0.041) (Olsen P, ppm)] (Expected Yield)

Potash fertilizer guidelines*

Expected Yield 0-40 ppm 41-80 ppm 81-120 ppm 121-160 ppm 160+ ppm
40-60 bu/acre 55 lb/acre 40 lb/acre 20 lb/acre 10 lb/acre 0 lb/acre
61-80 bu/acre 75 55 30 0 0
81-100 bu/acre 95 70 40 0 0
101-120 bu/acre 115 85 45 10 0
121+ bu/acre 130 90 50 10 0

*Pounds of K2O suggested to apply per acre for oat production 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 = [1.277 - (0.00086) (Soil Test K, ppm)] (Expected Yield)

Other nutrients

Except for the need for sulfur (S) when this crop is grown on sandy soils, other nutrients are not needed in a fertilizer program. For production on sandy soils, either use 10-12 pounds of sulfur per acre with the drill at planting or broadcast 25 pounds of sulfur per acre and incorporate before planting.

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

Reviewed in 2023

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