Tissue sampling program sets goals of yields, grain quality, test weight

IVESDALE, Ill. — Got GDUs? If so, how many? What kind of nutrients are your corn plants using at 750 GDUs? How about 1,150 GDUs?

How much and what kind of nutrients will that crop need to maximize not just yield, but grain fill and test weight?

Answering those kinds of questions is one goal of a tissue sampling program that AgriGold started with its grower customers to look beyond the early stages of corn plant growth and health to what the plant and the ear needs to finish strong.

“The tissue sampling has really helped us to help growers who want to get to those higher yield levels make sure they have the nutrient load going into that critical period,” said John Brien, eastern agronomy manager for AgriGold.

Brien is based on his family’s farm near Kenton, Ohio. He credits Randy Dowdy, a first-generation farmer from Valdosta, Georgia, who has become well-known in the U.S. corn and soybean universe.

In 2014, Dowdy raised a world record-breaking 503 bushels per acre corn crop. Since then, Dowdy raised a record-setting soybean crop, in 2016, at 171 bushels per acre.

As Dowdy’s yields broke records, his methods tested conventional wisdom. Among his practices is regular and widespread tissue testing throughout the growing season to determine the crop’s nutrient levels and nutrient needs.

“We took that as a group and have run with it,” Brien said.

Brien said AgriGold agronomists work with cooperating growers in their area to do tissue sampling at regular intervals, according to the level of growing degree units. The database has over 4,000 samples in it, with a GDU level and yield attached.

“We can run data. For example, at this GDU, this is what 300-bushel corn looks like for potassium, for nitrogen and those types of nutrients,” Brien said.

He said one of the major learning curves has been to change the thinking on how long the corn crop needs to be managed for nutrients.

“Once tasseling happens, we tend to walk away from the crop because we aren’t able, really, to manage it. What we are finding with our tissue sampling is from about 2,000 GDUs on is extremely critical to high yields. That’s when that corn plant is packing more starch into that kernel and, extremely important for end buyers, test weight, grain quality. That is when those are determined,” he said.

Brien said the sampling program allows agronomists to prepare the plant to take advantage of the later-season GDUs to maximize its full potential of producing, then nourishing, the ear.

“As we go into tasseling, how do we get that corn plant fully loaded and ready to go tap into that late GDU accumulation?” he said.

Being able to see firsthand, from tissue samples, how much nutrient the plant is using at the late stages of GDU accumulation helps agronomists and growers adjust their programs, especially for later-season nutrients.

“One of the neat things we’ve done, we see that, at 3/4 milk line, we still have about 25% of the yield to go. We’ve got 10 to 14 days before black layer. That’s not very much time when we have 25% more yield to go. Do we have the nutrients to put us there? Do we have the plant health to get us there? Do we have the water to get us there? That’s a lot of yield. I don’t want to lose that much yield when that corn is pineappling out there for three weeks, so I’m not worried about the stress, I’m worried about grain fill,” Brien said.

Joe Stephan, AgriGold regional agronomist for northern Indiana and southwest Michigan, said he sees growers in his territory working with the tissue sampling data to make more precise decisions on nutrient applications.

“I have 40-plus operations this year. We have more growers trying to be intentional with their fertility programming to make sure they are doing it right. We are getting better growers who are trying to follow the data that’s being offered to them,” he said.

Stephan added that growers who are adjusting their nutrient programs in response to data from the tissue testing program are answering one of the big questions that is commonly asked of data — is it of use to growers?

“We can collect data, but is anything being done with it? Yes. There are growers who are actively trying to get their nutrients in line to be 300-bushel corn growers,” he said.