Farmers who post top yields in the National Corn Growers Association yield competitions have formed groups in an effort to learn from each other. Many of these groups charge a sizable fee to join.

You can put one practice many of these farmers use to work for you without joining a high-yield group. Routine tissue testing during the season is a common denominator among many farmers who consistently turn out high corn yields, whether they participate in contests or not. Tissue testing comes with a cost, but it can provide valuable information.

Betsy Bower, a Ceres Solutions agronomist based in Terre Haute, Ind., and a certified crop adviser, works with several customers who rely on tissue testing to learn about their soil fertility. Some only test three times per year. Others test weekly or biweekly. If you’re only testing three times, Bower suggests doing so at the V5 stage, the grand growth stage between V9 and V12, and early R1.

Bower reveals more insight into tissue testing in this short interview with Indiana Prairie Farmer:

What can you learn from tissue testing weekly once corn reaches the five-leaf stage? Every-week tissue testing allows you to monitor nutrient status in corn through the season. You will be surprised at how much it can fluctuate week to week as the environment changes. Cool temperatures early in the season can slow nutrient uptake, showing low nutrient status in corn.

Rain followed by warm temperatures often speeds up corn growth and dilutes nutrient levels in the plant due to rapid growth. Dry or wet conditions allow you to see which nutrients are the first to be responsive or deficient in the plant.

It sounds like tissue sampling results could be confusing. They can be. Yet after testing for a few years — being sure to sample timely — you can get a feel for not only micronutrient status, but also your macronutrient nutrient program. Some of our biggest discoveries result from developing a program to adjust a macronutrient program for nitrogen, phosphorus and potassium, and a secondary nutrient program for magnesium and sulfur to ensure timely uptake in corn. Those adjustments to macronutrients have shown our largest yield responses.

A solid macronutrient plan allows the best response to a micronutrient addition, if needed, as well. Micronutrient needs will show up in tissue testing.

Why should you wait until V5 to pull tissue samples? If you start tissue sampling too soon, seedlings are still using remaining seed resources. At V5, you can get a pretty good picture of plant sufficiency of macro- and micronutrients.

Why do you emphasize the early R1 stage for later-season samples? The tissue sample at R1 needs to be early R1. Tony Vyn at Purdue University demonstrated there is a very narrow window at tasseling and early silking for a good picture of nitrogen status if your goal is making a good decision on additional nitrogen need.