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Strip trials can be deceptive

The crop is in the bin, and if you haven’t yet made your seed selections for next year, now is the time! Sure, some of your plans will change before next spring, but for the most part, you know what acres will go into what crop.

The availability of new corn hybrids and soybean varieties should be pretty good yet, but waiting can limit your seed choices. And placing the wrong hybrid/variety on a piece of ground can cost you 25% or more in yield potential. How do you choose the right seed, though? How do you pick through all the seed catalogs and yield data sheets to find that one right choice for each of your fields?

One method many growers use is looking at strip trials near their farm. The following is an example of the results from one of those types of trials that I did this year:

Hybrid Yield bu./ac. Moisture

A 222.2 16.8%

B 175.3 18.2%

C 163.6 18.8%

D 184.6 19.3%

E 172.7 18.2%

This strip was planted on an even piece of tiled ground that did not lack for nutrition all year. Which hybrid would you choose to plant next year? Hybrid A looks like the logical choice in this plot because it outyielded the second-place hybrid by nearly 40 bushels per acre while being almost 2% points drier. Or would you choose Hybrid C? It was 20 bushels per acre under the plot average and was the second wettest.

In truth, you cannot make an accurate selection using data from a plot like this. In reality, I used the same hybrid for all five of these strips. This just proves how much variability there is in a field even if you pick the most uniform ground for your plot. And this was only five hybrids. Can you imagine the amount of variability across the field in an eight-row, 25-entry plot?

Making a decision from a plot like this is making the choice of what did well this year — not what will do well next year.

Look at multiple years

To find what will work best for your farm you must look at multiple-year data performed over multiple locations. This will show varietal consistency and give you enough information to make your selection. Take into consideration the variety’s agronomic traits as well and how they will fit with each of your field’s individual “personalities.”

The only real way to conduct meaningful yield trials is by using replication of the entries in the plot. We replicate all of our entries three times at 10 locations per year, This minimizes field variability, allowing true genetic differences to be seen.

Make sure you know what kind of plot data you are examining before using it to make your seed selections. That seed decision is one of the most important decisions you’ll be making.

Spelhaug is an agronomist with Peterson Farms Seed, Harwood, N.D. Contact him at 866-481-7333 or visit

This article published in the November, 2010 edition of DAKOTA FARMER.

All rights reserved. Copyright Farm Progress Cos. 2010.