Understanding Seeding Methods and Amounts for Winter Wheat and Canola
Planting is one of the most critical management aspects in crop production systems. Getting the right amount of seed in the ground is key to ensure good emergence and early-season crop growth. However, determining the amount of seed to plant varies substantially between crops. Furthermore, different methods can be used to determine seeding rates. For most summer row-crops, seeding rates are recommended on a “seeds per acre” basis, while most cereals and winter annuals are planted on a “weight per acre” basis. Part of this difference can be contributed to the equipment traditionally used to plant each of these crops. Summer row-crops are traditionally planted with planters that can singulate seed better than traditional drills, which is how most cereal crops are planted.
Conversations have started in recent years for shifting both winter wheat and winter canola planting from a weight per acre to a seed per acre basis. This is partially due to differences in seed size within individual cultivars among various seed lots. This can result in large differences in the number of seeds planted per acre when planting on a constant weight basis. Additionally, because of expected differences in seed size between cultivars, seed amounts planted on a constant weight basis can vary drastically when changing cultivars.
Realizing the amount of seed being planted is crucial for Oklahoma producers to improve planting practices. For producers interested in shifting seeding rates from a weight per acre to a seeds per acre basis, it is important to understand how these methods differ.
Tables 1 through 4 are provided to show differences in seed amounts for each planting rate using different combinations of seeding rates and seed sizes. Currently, little data in winter wheat and no data in canola exists in the southern Great Plains that suggests one planting method is superior to the other. Therefore, the tables provided do not indicate preference of planting rate determination. Finally, it is important to remember that seed size (i.e., seeds/lb in this case) can vary among cultivars due to genetic potential and can vary among seed lots of the same cultivar, depending on management and environmental factors. Data in Tables 5 and 6 are provided as examples to demonstrate these differences. The listed cultivars are a small selection of those entered in the official Oklahoma State University cultivar testing programs for winter wheat and winter canola during the 2015 to 2017 growing seasons and do not indicate preference or performance of the cultivars.
Table 1. Wheat seed number per acre for different seed sizes if planting rate is held as a consistent weight per acre.
| Constant seed weight per acre | ||||
|---|---|---|---|---|
| Seeds/lb | 30 lbs | 60 lbs | 90 lbs | 120 lbs |
| - seeds/acre - | ||||
| 10,000 | 300,000 | 600,000 | 900,000 | 1,200,000 |
| 10,500 | 315,000 | 630,000 | 945,000 | 1,260,000 |
| 11,000 | 330,000 | 660,000 | 990,000 | 1,320,000 |
| 11,500 | 345,000 | 690,000 | 1,035,000 | 1,380,000 |
| 12,000 | 360,000 | 720,000 | 1,080,000 | 1,440,000 |
| 12,500 | 375,000 | 750,000 | 1,125,000 | 1,500,000 |
| 13,000 | 390,000 | 780,000 | 1,170,000 | 1,560,000 |
| 13,500 | 405,000 | 810,000 | 1,215,000 | 1,620,000 |
| 14,000 | 420,000 | 840,000 | 1,260,000 | 1,680,000 |
| 14,500 | 435,000 | 870,000 | 1,305,000 | 1,740,000 |
| 15,000 | 450,000 | 900,000 | 1,350,000 | 1,800,000 |
| 15,500 | 465,000 | 930,000 | 1,395,000 | 1,860,000 |
| 16,000 | 480,000 | 960,000 | 1,440,000 | 1,920,000 |
| 16,500 | 495,000 | 990,000 | 1,485,000 | 1,980,000 |
| 17,000 | 510,000 | 1,020,000 | 1,530,000 | 2,040,000 |
| 17,500 | 525,000 | 1,050,000 | 1,575,000 | 2,100,000 |
| 18,000 | 540,000 | 1,080,000 | 1,620,000 | 2,160,000 |
| 18,500 | 555,000 | 1,110,000 | 1,665,000 | 2,220,000 |
| 19,000 | 570,000 | 1,140,000 | 1,710,000 | 2,280,000 |
| 19,500 | 585,000 | 1,170,000 | 1,755,000 | 2,340,000 |
| 20,000 | 600,000 | 1,200,000 | 1,800,000 | 2,400,000 |
Table 2. Canola seed number per acre for different seed sizes if planting rate is held as a consistent weight per acre.
| Constant seed weight per acre | |||
|---|---|---|---|
| Seeds/lb | 1 lb | 3.8 lbs | 5 lbs |
| - seeds/acre - | |||
| 50,000 | 50,000 | 175,000 | 250,000 |
| 55,000 | 55,000 | 192,500 | 275,000 |
| 60,000 | 60,000 | 210,000 | 300,000 |
| 65,000 | 65,000 | 227,500 | 325,000 |
| 70,000 | 70,000 | 245,000 | 350,000 |
| 75,000 | 75,000 | 262,500 | 375,000 |
| 80,000 | 80,000 | 280,000 | 400,000 |
| 85,000 | 85,000 | 297,500 | 425,000 |
| 90,000 | 90,000 | 315,000 | 450,000 |
| 95,000 | 95,000 | 332,500 | 475,000 |
| 100,000 | 100,000 | 350,000 | 500,000 |
| 105,000 | 105,000 | 367,500 | 525,000 |
| 110,000 | 110,000 | 385,000 | 550,000 |
| 115,000 | 115,000 | 402,500 | 575,000 |
| 120,000 | 120,000 | 420,000 | 600,000 |
| 125,000 | 125,000 | 437,500 | 625,000 |
| 130,000 | 130,000 | 455,000 | 650,000 |
| 135,000 | 135,000 | 472,500 | 675,000 |
| 140,000 | 140,000 | 490,000 | 700,000 |
| 145,000 | 145,000 | 507,500 | 725,000 |
| 150,000 | 150,000 | 525,000 | 750,000 |
Table 3. Wheat seed pounds per acre for different seed sizes if planting rate is held as a consistent seeds per acre.
| Constant seed number per acre | ||||
|---|---|---|---|---|
| Seeds/lb | 500,000 | 1,000,000 | 1,500,000 | 2,000,000 |
| seeds | seeds | seeds | seeds | |
| - lb/acre - | ||||
| 10,000 | 50 | 100 | 150 | 200 |
| 10,500 | 48 | 95 | 143 | 190 |
| 11,000 | 45 | 91 | 136 | 182 |
| 11,500 | 43 | 87 | 130 | 174 |
| 12,000 | 42 | 83 | 125 | 167 |
| 12,500 | 40 | 80 | 120 | 160 |
| 13,000 | 38 | 77 | 115 | 154 |
| 13,500 | 37 | 74 | 111 | 148 |
| 14,000 | 36 | 71 | 107 | 143 |
| 14,500 | 34 | 69 | 103 | 138 |
| 15,000 | 33 | 67 | 100 | 133 |
| 15,500 | 32 | 65 | 97 | 129 |
| 16,000 | 31 | 63 | 94 | 125 |
| 16,500 | 30 | 61 | 91 | 121 |
| 17,000 | 29 | 59 | 88 | 118 |
| 17,500 | 29 | 57 | 86 | 114 |
| 18,000 | 28 | 56 | 83 | 111 |
| 18,500 | 27 | 54 | 81 | 108 |
| 19,000 | 26 | 53 | 79 | 105 |
| 19,500 | 26 | 51 | 77 | 103 |
| 20,000 | 25 | 50 | 75 | 100 |
Table 4. Canola seed pounds per acre for different seed sizes if planting rate is held as a consistent seeds per acre.
| Constant seed number per acre | |||
|---|---|---|---|
| Seeds/lb | 150,000 seeds | 250,000 seeds | 350,000 seeds |
| - lb/acre - | |||
| 50,000 | 3 | 5 | 7 |
| 55,000 | 2.7 | 4.5 | 6.4 |
| 60,000 | 2.5 | 4.2 | 5.8 |
| 65,000 | 2.3 | 3.8 | 5.4 |
| 70,000 | 2.1 | 3.6 | 5 |
| 75,000 | 2 | 3.3 | 4.7 |
| 80,000 | 1.9 | 3.1 | 4.4 |
| 85,000 | 1.8 | 2.9 | 4.1 |
| 90,00 | 1.7 | 2.8 | 3.9 |
| 95,000 | 1.6 | 2.6 | 3.7 |
| 100,00 | 1.5 | 2.5 | 3.5 |
| 105,000 | 1.4 | 2.4 | 3.3 |
| 110,000 | 1.4 | 2.3 | 3.2 |
| 115,00 | 1.3 | 2.2 | 3 |
| 120,000 | 1.3 | 2.1 | 2.9 |
| 125,000 | 1.2 | 2 | 2.8 |
| 130,000 | 1.2 | 1.9 | 2.7 |
| 135,000 | 1.1 | 1.9 | 2.6 |
| 140,000 | 1.1 | 1.8 | 2.5 |
| 145,000 | 1 | 1.7 | 2.4 |
| 150,000 | 1 | 1.7 | 2.3 |
Table 5. Example of differences in wheat and canola seeds per pound among cultivars and years, 2014-2016.
| Year | ||||
|---|---|---|---|---|
| Crop | Cultivar/Hybrid | 2016 | 2015 | 2014 |
| - seeds/lb - | ||||
| Wheat† | Bentley | 14,942 | 13,985 | 13,526 |
| Doublestop CL+ | 11,297 | 13,309 | 14,375 | |
| Duster | 14,170 | 25,107 | 18,822 | |
| Endurance | 12,462 | 14,756 | 14,831 | |
| Gallagher | 12,496 | 16,761 | 17,050 | |
| Iba | 14,083 | 19,949 | 14,699 | |
| Ruby Lee | 15,385 | 15,009 | 14,036 | |
| Canola | DKW 44-10 | 130,227 | 133,138 | 117,541 |
| DKW 46-15 | 97,845 | 106,740 | --- | |
| HyClass 115 | 115,427 | 105,581 | 129,420 | |
| Pioneer 46W94 | 98,784 | 85,714 | 81,264 | |
| Wichita | --- | 109,486 | 124,848 | |
| Mercedes | 103,151 | 5,6421 | --- |
† Data provided by the Oklahoma Crop Improvement Association.
Table 6. Example of differences in wheat seeds per pound among three different lots of cultivars Bentley, Doublestop CL +, and Gallagher produced in 2016.
| Lot | |||
|---|---|---|---|
| Cultivar | 1 | 2 | 3 |
| - seeds/lb - | |||
| Bentley | 13,680 | 13,708 | 13,191 |
| Doublestop CL + | 11,403 | 11,036 | 11,345 |
| Gallagher | 12,151 | 12,315 | 13,023 |
David Marburger
Former Small Grains Extension Specialist
Josh Lofton
Cropping Systems Specialist