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.
Reviewed in 2023