Population Rates: the Devil's in the Details

It's important to count final stands.

Published on: January 16, 2009

With planting season around the corner, I've heard a lot of talk about population rates.

 

For some reason, everyone likes discuss population rates during planting, but talk switches over to yield once the growing season starts. University of Illinois Extension agronomist Emerson Nafziger conducts population studies according to final stands.

 

So, what's it matter if you're counting kernels or plants? A lot of experts say the difference between what the planter is set at and the actual final stand is usually around 5%. Therefore, if you think you're pushing the limit with 40,000 kernels per acre, you may only be planting 38,000 kernels. With today's seed costs, who can afford to be off by 2,000 kernels per acre?

 

Gregg Sauder, Precision Planting owner, says farmers should always check final stands. Sauder has a fairly simple formula for counting final stands. On 30-inch rows, mark off 17.5 feet (1/10 an acre), count the number of ears and multiply it by 1,000. According to North Carolina State University, you should mark off 26 feet on 20-inch rows and 35 feet on 15-inch rows.

By checking final stands, Sauder says he can identify whether his planter is skipping, planting doubles or screwing up spacing. And don't just count plants. Sauder counts full mature ears, not plants. If the planter did a bang up job but you still lost yield, you'll want to know why.

 

At the end of the day, it's all about adding yield. Knowing which yield robbers got to your plants last year can help you prepare for next year.

 

By the way, various experts are saying Illinois farmers with high-quality soils are planting an average of 34,000 to 36,000 kernels. What are your thoughts on population rates? If you've pushed them in the past, did extra yield pay for the seed? Be sure to check out the February Prairie Farmer for more on population rates.

 

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