Quick facts
- Sunflower is highly responsive to nitrogen (N).
- Nitrogen rates should be adjusted for the type of sunflower grown.
- Suggested nitrogen fertilizer rates are no longer based on yield goals minus N fertilizer credits, as recent data has not shown a link between the yield of sunflower and N fertilizer requirements.
Recommended nitrogen fertilizer rates
Recommended rates of nitrogen (N) should be based on the value of the sunflower seed in price per harvested pound and the unit price per pound of N applied.
The suggested rate of nitrogen also varies based on the type of sunflower grown.
- Guidelines are based on suggestions for sunflower grown under conventional tillage for Eastern North Dakota, which has a similar climate and soils as Northwest Minnesota.
- Suggested first and second year N credits are listed in Tables SF-3 and SF-4.
The N rates suggested in the tables below include all known sources of N, including the amount of Nitrate-N in a two-foot soil sample and any N credits from previous crops. We suggest sampling for Nitrate-N. Samples can be collected in the fall after the previous crop has been harvested.
Nitrogen application rate tables
Total known available N (lb/acre) for oilseed sunflower in situations based on N cost and harvested sunflower seed price per pound*
| Seed price | N use @$.20/lb | N use @$.30/lb | N use @$.40/lb | N use @$.50/lb | N use @$.60/lb | N use @$.70/lb | N use @$.80/lb | N use @$.90/lb | N use @$1/lb |
|---|---|---|---|---|---|---|---|---|---|
| $0.09/lb | 150 lb | 135 lb | 124 lb | 111 lb | 96 lb | 84 lb | 72 lb | 59 lb | 47 lb |
| $0.12 | 150 | 145 | 135 | 125 | 116 | 106 | 96 | 87 | 78 |
| $0.15 | 150 | 150 | 143 | 135 | 127 | 119 | 112 | 104 | 96 |
| $0.18 | 150 | 150 | 148 | 141 | 135 | 128 | 126 | 115 | 109 |
| $0.21 | 150 | 150 | 150 | 146 | 141 | 135 | 129 | 124 | 118 |
| $0.24 | 150 | 150 | 150 | 150 | 145 | 140 | 135 | 130 | 125 |
| $0.27 | 150 | 150 | 150 | 150 | 148 | 144 | 139 | 135 | 131 |
| $0.30 | 150 | 150 | 150 | 150 | 150 | 147 | 143 | 139 | 135 |
| $0.33 | 150 | 150 | 150 | 150 | 150 | 150 | 150 | 150 | 138 |
| $0.36 | 150 | 150 | 150 | 150 | 150 | 150 | 150 | 150 | 142 |
| $0.39 | 150 | 150 | 150 | 150 | 150 | 150 | 150 | 150 | 144 |
| $0.42 | 150 | 150 | 150 | 150 | 150 | 150 | 150 | 150 | 146 |
| $0.45 | 150 | 150 | 150 | 150 | 150 | 150 | 150 | 150 | 148 |
| $0.48 | 150 | 150 | 150 | 150 | 150 | 150 | 150 | 150 | 150 |
| $0.51 | 150 | 150 | 150 | 150 | 150 | 150 | 150 | 150 | 150 |
| $0.55 | 150 | 150 | 150 | 150 | 150 | 150 | 150 | 150 | 150 |
| $0.60 | 150 | 150 | 150 | 150 | 150 | 150 | 150 | 150 | 150 |
*Total known available N includes soil test N to 2 feet, previous crop credit, and fertilizer amendment N rate.
This table is adapted from NDSU Extension Publication SF713.
Total known available N (lb./acre) for confection sunflower in situations based on N cost and harvested sunflower seed price per pound*
| Seed price | N use @$.20/lb | N use @$.30/lb | N use @$.40/lb | N use @$.50/lb | N use @$.60/lb | N use @$.70/lb | N use @$.80/lb | N use @$.90/lb | N use @$1/lb |
|---|---|---|---|---|---|---|---|---|---|
| $0.09/lb | 160 lb | 107 lb | 43 lb | 0 lb | 0 lb | 0 lb | 0 lb | 0 lb | 0 lb |
| $0.12 | 160 | 155 | 107 | 59 | 11 | 0 | 0 | 0 | 0 |
| $0.15 | 160 | 160 | 145 | 107 | 69 | 30 | 0 | 0 | 0 |
| $0.18 | 160 | 160 | 160 | 139 | 107 | 75 | 43 | 11 | 0 |
| $0.21 | 160 | 160 | 160 | 160 | 134 | 107 | 79 | 52 | 25 |
| $0.24 | 160 | 160 | 160 | 160 | 155 | 131 | 107 | 83 | 59 |
| $0.27 | 160 | 160 | 160 | 160 | 160 | 149 | 128 | 107 | 86 |
| $0.30 | 160 | 160 | 160 | 160 | 160 | 160 | 145 | 126 | 107 |
| $0.33 | 160 | 160 | 160 | 160 | 160 | 160 | 160 | 142 | 139 |
| $0.36 | 160 | 160 | 160 | 160 | 160 | 160 | 160 | 155 | 151 |
| $0.39 | 160 | 160 | 160 | 160 | 160 | 160 | 160 | 160 | 160 |
| $0.42 | 160 | 160 | 160 | 160 | 160 | 160 | 160 | 160 | 160 |
| $0.45 | 160 | 160 | 160 | 160 | 160 | 160 | 160 | 160 | 160 |
| $0.48 | 160 | 160 | 160 | 160 | 160 | 160 | 160 | 160 | 160 |
| $0.51 | 160 | 160 | 160 | 160 | 160 | 160 | 160 | 160 | 160 |
| $0.55 | 160 | 160 | 160 | 160 | 160 | 160 | 160 | 160 | 160 |
| $0.60 | 160 | 160 | 160 | 160 | 160 | 160 | 160 | 160 | 160 |
*The total known available N includes soil test N to 2 feet, previous crop credit, and fertilizer amendment N rate.
This table is adapted from NDSU Extension Publication SF713.
Suggested nitrogen credits for various crops that might precede sunflower 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 alfalfa1 or non-harvested sweet clover (4-5 plants/ft2) | 75 |
| Harvested alfalfa1 or non-harvested sweet clover (2-3 plants/ft2) | 50 |
| Harvested alfalfa1 or non-harvested sweet clover (1-2 plants/ft2) | 25 |
| Harvested alfalfa1 or non-harvested sweet clover (1 or fewer plants/ft2) | 0 |
| Harvested red clover | 35 |
| Sugar beet, yellow leaves at harvest | 0 |
| Sugar beet, light-green leaves at harvest | 15-30 |
| Sugar beet, dark-green leaves at harvest | 60-80 |
*Use these credits when the soil nitrate test is used.
For harvested alfalfa, if the third or fourth cutting was not harvested, add 20 pounds of N per acre to the N credits listed.
Suggested nitrogen credits when sunflower is grown 2 years after a legume crop
| Previous legume crop | 2nd 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, potash and other nutrients
Phosphate fertilizer guidelines for sunflower production based on either the Bray-P1 or Olsen soil methods test reported in parts per million (ppm)
| Expected yield: Bray-P1 and Olsen | 0-5 ppm (Bray), 0-3 ppm (Olsen) | 6-10 ppm (Bray), 4-7 ppm (Olsen) | 11-15 ppm (Bray), 8-11 ppm (Olsen) | 16-20 ppm (Bray), 12-15 ppm (Olsen) | 21+ ppm (Bray), 16+ ppm (Olsen) |
|---|---|---|---|---|---|
| 1400-1900 lb/acre | 55 lb/acre | 35 lb/acre | 15 lb/acre | 0 lb/acre | 0 lb/acre |
| 1901-2400 lb/acre | 65 | 45 | 20 | 0 | 0 |
| 2401-2900 lb/acre | 75 | 55 | 25 | 0 | 0 |
| 2901-3300 lb/acre | 85 | 65 | 25 | 10 | 0 |
| 3300+ lb/acre | 90 | 70 | 30 | 10 | 0 |
Use one of the following equations if you want a phosphate guideline for a specific soil test and a specific expected yield:
- P2O5 rec = [0.0225 - (0.0011) (Bray P in ppm)] (Expected yield)
- P2O5 rec = [0.0225 - (0.0014) (Olsen P in ppm)] (Expected yield)
Potash fertilizer guidelines for sunflower production based on the ammonium acetate potassium test reported in parts per million (ppm)
| Expected yield | 0-40 ppm | 41-80 ppm | 81-120 ppm | 121-160 ppm | 161+ ppm |
|---|---|---|---|---|---|
| 1400-1900 lb/acre | 55 lb/acre | 40 lb/acre | 20 lb/acre | 10 lb/acre | 0 lb/acre |
| 1901-2400 lb/acre | 75 | 50 | 30 | 15 | 0 |
| 2401-2900 lb/acre | 90 | 65 | 35 | 20 | 0 |
| 2901-3300 lb/acre | 110 | 75 | 40 | 25 | 0 |
| 3301+ lb/acre | 115 | 80 | 45 | 25 | 0 |
Use the following equation if you want a potash guideline for a specific soil test and a specific expected yield:
- K2O rec = [0.0410 - (0.00027) (Soil test K in ppm)] (Expected yield)
CAUTION: Do not apply more than 10 pounds N + K2O per acre in contact with the seed for medium to fine textured soils. Starter fertilizer placed on the seed is not suggested for sandy textured soils.
Research trials conducted in Minnesota have shown that most secondary macronutrients and micronutrients are not needed in a fertilizer program for sunflower production.
The need for sulfur (S) for sunflower has not been evaluated in Minnesota. The likelihood of sulfur deficiency on soils high in clay content (loam soils or heavier) is low if soil organic matter content is 2-3% or greater in the top six inches. The likelihood of an S deficiency is greater for sandy-textured soils low in organic matter. If a sulfur deficiency is anticipated, an application of 10 pounds of S in the sulfate form at or before planting or post-emergence before the R1 growth stage may be required. We suggest you apply a sulfate or thiosulfate form.
Caution: 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.
North Dakota State University Extension. NDSU Fertilizing Sunflower Guide. 2022. https://www.ndsu.edu/agriculture/sites/default/files/2022-08/sf713.pdf
Reviewed in 2026