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 N 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 N also varies based on the type of sunflower grown.
- Nitrogen suggestions for oilseed sunflower are given in Table SF-1.
- Suggestions for confection sunflower production are given in Table SF-2.
- Guidelines are based on suggestions for sunflower grown under conventional tillage for Eastern North Dakota, which has 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 Tables SF-1 and SF-2 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.
For more specific recommendations, North Dakota State University has an interactive sunflower N calculator.
Nitrogen application rate tables
Table SF-1. Total known available N (lb./acre) for oilseed sunflower in situations based on N cost and sunflower harvest price. Total known available N includes soil test N to 2 feet, previous crop credit and fertilizer amendment N rate.
* Chart adapted from NDSU Extension Publication SF713.
Sunflower seed price per pound harvested | 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 |
$0.60 | 150 | 150 | 150 | 150 | 150 | 150 | 150 | 150 | 150 |
Table SF-2. Total known available N (lb./acre) for confection sunflower in situations based on N cost and sunflower harvest price. Total known available N includes soil test N to 2 feet, previous crop credit and fertilizer amendment N rate.
*Chart adapted from NDSU Extension Publication SF713.
Sunflower seed price per pound harvested | N use @$.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 |
Table SF-3. Suggested nitrogen credits for various crops that might precede sunflower in a crop rotation. 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 N per acre to the N credits listed.
Previous crop | 1st 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 |
Sugarbeet | |
Yellow leaves at harvest | 0 |
Light-green leaves at harvest | 15-30 |
Dark-green leaves at harvest | 60-80 |
Table SF-4. 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
Table SF-5. Phosphate fertilizer guidelines (pounds of P2O5 suggested to apply per acre) for sunflower 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 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)
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 |
---|---|---|---|---|---|
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 |
Table SF-6. Potash fertilizer guidelines (pounds of K2O suggested to apply per acre) for sunflower production based on the ammonium acetate potassium test reported in parts per million (ppm).
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.
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 |
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.
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.
NDSU Fertilizing Sunflower Guide: https://www.ndsu.edu/agriculture/sites/default/files/2022-08/sf713.pdf
Reviewed in 2023