A Word About Side-by-Side Test Plots and Replication

One of the most popular methods of evaluating new products in the field is with side-by-side test plots. The reason is because a side-by-side plot is easy to set up and easy to obtain results at harvest. But as we all know, quick and easy is not always the best path to take. This is certainly true with side-by-side comparisons. I’ll explain why.

In a side-by-side comparison we always have 2 sides. Your probably thinking “well duh!”, but stick with me. Those 2 side can be anything, i.e., 2 halves of a field, 2 passes of a sprayer, 2 passes of a planter, etc., etc. What’s important to consider is the fact that even before treating the 2 sides with the product you are evaluating, those 2 sides will almost never yield the same. What this means is that one side will always have an advantage over the other, right from the start. Personally, I’ve seen as much as a 25 bu. yield difference between 2 eight row passes with a combine. Usually the variance is in the 5-7 bu. range, but it often can be more.

If  I have a product to sell, a side-by-side plot is my best friend. Because the 2 sides never yield the same it means that I have a 50% chance of winning the plot even if my product does nothing. I’ll take those odds because half of the people who try my product will be satisfied and I’ll have a great base to build upon.

This doesn’t mean that side-by-sides are completely useless. The trick is to have multiple side-by-sides in a given year for a given product. These multiple side-by-sides can be accomplished not only in the same field, but in multiple fields. If you want to do a split field, do it on multiple fields. In order to get accurate data that can be trusted, it is generally recommended to do at least 6 replications. If you do split fields, split 6 different fields. If it’s by planter width, set up 6 different trials by width.

No matter how you do it, it’s important to replicate! Then, if you see a yield advantage across multiple trials, you can be much more confident that the product you are evaluating is actually providing a benefit. Yes, it does take more time to do it in this manner, but in the end you’ll be money ahead.

This entry was posted in Agriculture, Agronomy, Corn, Fertilizer, Soybean, Uncategorized, Wheat and tagged , , , , . Bookmark the permalink.

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