Seeding rates & emergence: A package deal

Jeremy Boychyn, Agronomy and Extension, Director | Alberta Grains

Wheat and barley yield comes down to a few fundamental components: the number of heads per sq. foot, the number of kernels per head and the weight of those kernels.

The most influential of those three factors is the number of heads per sq. foot. For example, the total number of heads per sq. foot (headcount) has a stronger influence on final yield than kernel weight. Seeding rate has an impact on the crop’s plant stand and subsequently, the total head count. This means you can greatly influence the final number of heads per sq. foot through seeding rate.

If you are already seeding based on seed rate targets rather than a consistent number of lb./ac, you are already ahead of the curve. However, appropriate seeding rates calculated using thousand kernel weight (TKW) are just the start. If you want to take your agronomy to the next step, plant stands and the number of heads/sq. ft data collection should also be taking place.

I don’t need to tell you that each year is different when it comes to seedling emergence. Whether that is due to environmental differences year to year or if you’ve purchased new seeding equipment. But, what I can’t tell you is how much variance occurs year to you on your farm.

Seeding rate recommendations come from the gathering of multiple small plot research results. These small plot trials assess the impact of different seeding rates on yield and quality. What we are left with is seeding rate recommendations targeting the highest yield potential without sacrificing too much quality or other agronomic factors.

Small plot research in Western Canada has continuously demonstrated that higher seeding rates (300-400 seeds/m2 (28-37 seeds/sq. ft.) for spring wheat and 300 seeds/m2 (28 seed/sq. ft.) for barley) produce higher yields with greater yield.

Seeding based on the number of seeds per square unit area was not always the norm. If you look at the historic Government of Alberta literature, the recommendations were to target a plant stand range. The Manitoba Government still provides recommendations that target plant stands.

Each farm manages the seeding process differently. Each farm has different equipment, soil, and residue and encounters different growing conditions. These differences impact the percentage of sown seeds that become established plants.

Knowing the percentage of seeds that produce plants on your farm conditions is fundamental for two reasons. First, it will impact the number of seeds you should be sowing. Second, it will impact the number of heads you produce per sq. foot. The number of plants per sq. foot has a strong relationship with the number of heads per sq. foot.

Recent research by Collier et al., 2021 investigated the impacts of ultra-early seeding on spring wheat. They applied two seeding rates (200 seeds/m2 (19 seeds/sq. ft.) and 400 seeds/ m2 (37 seeds/sq. ft.) and four seeding dates for temperatures ranging from 0C to 10C.

At a target seeding rate of 200 seeds/m2 (18 seeds/sq. ft.), the emergence percentage was 83%, resulting in 160 plants/ m2 (15 plants/sq. ft.). At a target seeding rate of 400 seeds/m2 (37 seeds/sq. ft.), the emergence percentage was 59%, resulting in 240 plants/m2 (22 plants/sq. ft.). The 400 seed/m2 (37 seeds/ sq. ft.) seeding rate resulted in a 3.87 bu./ac increase (5.54%) above the 200 seeds/m2 (19 seeds/sq. ft.) seeding rate.

These results tell us a couple of things. First, if your average emergence percentage is 59%, the ideal seed seeding rate is 400 seeds/m2 (37 seeds/sq. ft.). Second, it tells us that 240 plants/m2 (22 plants/sq. ft.) provided the best yield target.

O’Donovan et al., 2012 research investigated the impacts of malt barley seeding rates on yield and quality. Results indicated the seeding rate of 300 seeds/m2 (28 seeds/sq. ft.) provided the best yield and quality. This study established the recommended seeding rate of 300 seeds/m2 (28 seeds/sq. ft.) for malt barley. It’s important to know that, in the trial, the average plant stand achieved when seeding at 300 seeds/m2 (28 seeds/sq. ft.) was 200 plants/m2 (19 plants/sq. ft.).

What does this mean for farm decisions?

If you are targeting seeds per sq. foot, fantastic. If you are not collecting plant stand data to determine plant emergence on your farm, you should start. After collecting plant stand data for several years, you can determine if you have a consistent or variable emergence rate. If emergence is consistent, you may be better off agronomically and economically by targeting plant stand rather than seeding rates. If your emergence is variable, you can begin investigating the reason for variable emergence and adjust to fix it (a topic for another article). If your emergence is variable, it may be safer to seed based on target seeding rates to minimize the risk of ending up with a lower-than-optimum plant stand.


Collier, G. R., Spaner, D. M., Graf, R. J., and Beres, B. L. (2021). Optimal agronomics increase grain yield and grain yield stability of ultra-early wheat seeding systems. Agronomy, 11(2), 240.

O’Donovan, J. T., Turkington, T. K., Edney, M. J., Juskiw, P. E., McKenzie, R. H., Harker, K. N., ... and Smith, E. (2012). Effect of seeding date and seeding rate on malting barley production in Western Canada. Canadian Journal of Plant Science, 92(2), 321-330.