Just about every crop decision is based on one simple question: how can I increase yield potential? How do you answer that question when it comes to seeding rates in corn?
Research out of Nebraska identified four yield environments for corn – low, medium, high and very high. These levels refer to the growth-promoting and growth-limiting factors that define each area, such as soil quality, heat units, water availability and so on. Researchers also found that yield environment was the strongest correlation factor between plant population and grain yield.
So to find your ideal seeding rate for corn, you need to start by knowing what your yield environment is. Irrigated regions of southern Alberta fall into the medium yield environment while dryland areas are in the low yield category.
Next, choose hybrids that are well suited to your yield environment, based on CHU ratings, then plant the appropriate population. And what is the appropriate population? Research* done in Lacombe and Brooks tested corn hybrids at 30,000 plants per acre (ppa) and 40,000 ppa and found that the percent ear relative to the whole plant decreased by 9.3% when plant populations were increased.
So what’s ideal? In a low yield environment that accumulates less than 2200 CHU, a good target is 24,000 to 28,000 ppa. In areas that accumulate more than 2200 CHU, a target of up to 32,000 ppa is recommended.
And keep an eye on it throughout the season to see if you need to make adjustments in subsequent years. If more than 5% of plants are barren, then the ppa was too high.
Don’t hesitate to call your local CAM if you want to talk it over and figure out what’s right for your farm.
We’re here to help!
* Agriculture and Agri-Food Canada and Alberta Agriculture Food and Rural Development.