Stalk Tests Before Harvest Worth Taking

Use it as the report card on your nitrogen program for that year.

Published on: Sep 20, 2010

Thousands of pieces of corn stalk, each precisely 8 inches long, cut at precisely the same place every time from the stalk, sit in hundreds of bags inside the sampling room at G & K Concepts near Harlan, Ind., a mile west of the Ohio line and only a few miles form Michigan. Soon these samples will be sent for analysis for nitrates at Brookside Labs in east-central Ohio.

Greg Kneubuhler of G & K knows the process involves a lot of hard work and money on testing. But he believes it closes the loop on analysis of a farmer's nitrogen program in that field for that year. The higher the nitrate content within the stalk at this stage, right before harvest, the higher the odds that the left money on the table, supplying more nitrogen than the plant could use. If the levels are too low, he left yield on the table by not adding enough N and pushing plants hard enough.

The stalk nitrate test was developed decades ago by Fred Blackmere, a world-famous scientist at Iowa State University. He developed a range of numbers that farmers who ran the tests could compare too. Kneubuhler and associates have run enough samples that they're developing their own, much tighter range for the 14 counties they work with in the Tri-State region. If a grower has stalk tissue analyzed and get s a report on amou8nt of nitrate left in the stalks, he can then compare it to their ranges they've found throu8gh testing, and see where he stacks up.

It's just part of the tests that G & K run on replicated plots that they have out on a number of farms in the area. There are about 60 plots in all, with nitrogen rates this year ranging from 100 to 250 bushels per acre. All plots are sidedressed. The plot setup is so simple that the only time the farmer has to do something different is when he sidedresses, and when he combines. He changes the setting from strip to strip at sidedressing, and records data while combining. Actually, most of the time, G &K do that step, taking the data off yield maps. The plots are actually strips that run the entire length of each field where a plot is laid out.

"We've had so much interest we've had to turn people away this year," Kneubuhler says. "Nitrogen is an important asset, and a big part of the budget for growing corn. People want to know if they're applying enough, too much, or just where they stand."

Partially funded by an environmental group, the studies are designed to not only help farmers zero in on the right rates but also hopefully help protect natural resources, primarily water supplies, by not putting excess nitrates into the system. If farmers can get by on less nitrogen at application time, they same money, plus there's less nitrate left to pass into tile lines and eventually wind up in a body of water.