Weighty matters: Achieving your optimal seeding rate
Use thousand kernel weight to target your ideal rate this spring
Your optimal seeding rate is not only unique to you, but it’s also unique to your land’s capability, crop type, equipment, seed variety, your comfort level, cash flow, and the habits you’ve developed over the years.
As a result, optimizing your seeding rate this spring will look different from the farm down the road, and even from field to field on your own farm. Common to everyone is that achieving optimal seeding rate means getting the surviving plant stand you need to maximize yield, quality and a good return on your investment.
One of the key factors every farmer should incorporate into the calculation of optimal seeding rate is the thousand kernel weight (TKW) of a seed lot. This is literally the weight of 1,000 seeds, and since seed sizing can vary dramatically by crop, I have developed the following guidelines for canola, soybeans and spring wheat.
Crop Type |
Target Seeds per square foot |
Target Plant Stand | TKW and Target Seeding Rate per Acre (ac) |
|---|---|---|---|
| Canola | Minimum 10 seeds/sq ft | 5-7 surviving plants/sq ft |
3.2 grams TKW = 3 lb/acre 7.0 g TKW = 6.7 lb/ac |
| Soybeans | 4.5-5 seeds/sq ft |
3.5 surviving plants/sq ft |
135 g TKW = 61 lb/ac 165 g TKW = 74 lb/ac |
Spring wheat |
40 seeds/sq ft |
28-32 surviving plants/sq ft |
34 g TKW = 130 lb/ac 43 g TKW = 165 lb/ac |
*When seeding with a planter your mortality may be reduced (better) in soybeans and canola. Remember to take this into consideration when calculating optimal seeding rate.
Using thousand kernel weight in your calculations is not a guarantee of success, but it’s one important way to get closer to your optimal seeding rate. That in turn can help you achieve: the yield and quality you’re looking for; even crop maturity, which makes herbicide and fungicide application timing easier; quality of next year’s cereal seed; and more convenient harvest completion.
If you have questions about calculating your optimal seeding rate, contact your local Cargill agronomist, who can help navigate thousand kernel weight and other seeding considerations.