By: Mitchell Japp, MSc, PAg, Provincial Specialist, Cereal Crops
Have you ever walked through your field shortly after the crop has emerged and been disappointed in the stand? No doubt many possible reasons went through your mind – poor germination, dry soil, salinity… the list goes on. But, did your list include the number of seeds sown?
Seeding by volume or weight is easy, but it’s not a reliable way to establish a consistent plant stand. Seeding for a target plant stand is most effective at establishing the crop and helps to ensure a healthy plant stand. What you start with establishes the potential for your crop.
A single seed of a small grain crop like wheat, barley, canola, flax or lentils weighs very little. You don’t even notice when you hold it in your hand. Even the most experienced of us are unable to guess the weight of a seed in our hand.
Starting with such a tiny seed makes the differences between seeds minimal. But that doesn’t mean they’re not important!
Seed weight is the weight of a single seed in milligrams, but is commonly measured as thousand kernel weight (TKW) – the weight of 1,000 seeds in grams. TKW varies between varieties, but also varies from year to year and field to field, regardless of variety. Seeding by weight or volume does not account for the tiny differences in seed weight and will influence the final plant stand.
For example, in this year’s regional variety trials, the TKW for Canada Western Red Spring wheat ranges from 33 to 46 grams. All those varieties were grown on small plots at the same location. In 2015, the greatest seed weight was only 38.7 grams.
You may be thinking, “It’s only a few grams!” Actually, a few grams makes a big difference. In the chart below, the actual plants per square foot drop from 26 to 18, depending on whether the seed is big or small, all seeded at 90 pounds per acre. A thin plant stand is less competitive with weeds, and extensive tilling extends the period the crop is susceptible to some diseases and insects. Proper timing of pesticide applications would be more challenging.
The plant stand establishes the yield potential for your crop. Get the plant stand you want by using thousand kernel weight and a target plant stand.
For more information, visit the 1,000 kernel weight factsheet or contact the Agriculture Knowledge Centre at 1-866-457-2377.