Understanding Seeding Methods and Amounts for Winter Wheat and Canola

July 2017


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/lb30 lbs60 lbs90 lbs120 lbs
--------------- seeds/acre ---------------
10,000300,000600,000900,0001,200,000
10,500315,000630,000945,0001,260,000
11,000330,000660,000990,0001,320,000
11,500345,000690,0001,035,0001,380,000
12,000360,000720,0001,080,0001,440,000
12,500375,000750,0001,125,0001,500,000
13,000390,000780,0001,170,0001,560,000
13,500405,000810,0001,215,0001,620,000
14,000420,000840,0001,260,0001,680,000
14,500435,000870,0001,305,0001,740,000
15,000450,000900,0001,350,0001,800,000
15,500465,000930,0001,395,0001,860,000
16,000480,000960,0001,440,0001,920,000
16,500495,000990,0001,485,0001,980,000
17,000510,0001,020,0001,530,0002,040,000
17,500525,0001,050,0001,575,0002,100,000
18,000540,0001,080,0001,620,0002,160,000
18,500555,0001,110,0001,665,0002,220,000
19,000570,0001,140,0001,710,0002,280,000
19,500585,0001,170,0001,755,0002,340,000
20,000600,0001,200,0001,800,0002,400,000
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/lb1 lb3.5 lbs5 lbs
--------------- seeds/acre ---------------
50,00050,000175,000250,000
55,00055,000192,500275,000
60,00060,000210,000300,000
65,00065,000227,500325,000
70,00070,000245,000350,000
75,00075,000262,500375,000
80,00080,000280,000400,000
85,00085,000297,500425,000
90,00090,000315,000450,000
95,00095,000332,500475,000
100,000100,000350,000500,000
105,000105,000367,500525,000
110,000110,000385,000550,000
115,000115,000402,500575,000
120,000120,000420,000600,000
125,000125,000437,500625,000
130,000130,000455,000650,000
135,000135,000472,500675,000
140,000140,000490,000700,000
145,000145,000507,500725,000
150,000150,000525,000750,000
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/lb500,0001,000,0001,500,0002,000,000
seedsseedsseedsseeds
--------------------- lb/acre --------------------
10,00050100150200
10,5004895143190
11,0004591136182
11,5004387130174
12,0004283125167
12,5004080120160
13,0003877115154
13,5003774111148
14,0003671107143
14,5003469103138
15,0003367100133
15,500326597129
16,000316394125
16,500306191121
17,000295988118
17,500295786114
18,000285683111
18,500275481108
19,000265379105
19,500265177103
20,000255075100
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/lb150,000 seeds250,000 seeds350,000 seeds
-------------------- lb/acre --------------------
50,000357
55,0002.74.56.4
60,0002.54.25.8
65,0002.33.85.4
70,0002.13.65
75,00023.34.7
80,0001.93.14.4
85,0001.82.94.1
90,0001.72.83.9
95,0001.62.63.7
100,0001.52.53.5
105,0001.42.43.3
110,0001.42.33.2
115,0001.32.23
120,0001.32.12.9
125,0001.222.8
130,0001.21.92.7
135,0001.11.92.6
140,0001.11.82.5
145,00011.72.4
150,00011.72.3
Table 5. Example of differences in wheat and canola seeds per pound among cultivars and years, 2014-2016.    
† Data provided by the Oklahoma Crop Improvement Association.
Year
CropCultivar/Hybrid201620152014
-------------- seeds/lb --------------
Wheat†Bentley14,94213,98513,526
Doublestop CL+11,29713,30914,375
Duster14,17025,10718,822
Endurance12,46214,75614,831
Gallagher12,49616,76117,050
Iba14,08319,94914,699
Ruby Lee15,38515,00914,036
CanolaDKW 44-10130,227133,138117,541
DKW 46-1597,845106,740---
HyClass 115115,427105,581129,420
Pioneer 46W9498,78485,71481,264
Wichita---109,486124,848
Mercedes103,1515,6421---
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
Cultivar123
-------------------- seeds/lb --------------------
Bentley13,68013,70813,191
Doublestop CL +11,40311,03611,345
Gallagher12,15112,31513,023

 

David Marburger
Former Small Grains Extension Specialist

Josh Lofton
Cropping Systems Specialist

 

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