“Provide sufficient nutrients for the crop to produce maximum economic yields. That includes making sure there will be enough nutrients there when the crop needs them most.” This is the mantra that guides Troy Jenkins when he works with retailers and growers to ensure that crops make the best use of each dollar invested in fertilizer.

“For corn, nitrogen is typically the most expensive nutrient,” says Jenkins, Rochester, Ind. He is an agronomist with 34 years of experience, covering north-central Indiana and southern Michigan for Ceres Solutions.

“We believe strongly in the 4R concept,” he explains. “We focus on the right source of nutrients applied at the right rate, in the right place where roots can use it, all done at the right time.

“For nitrogen, right time means supplying enough during reproductive phases, when corn needs a lot of N. If someone sidedresses and applies part of the nitrogen requirements during the season, they could achieve 0.85 nitrogen efficiency. That means they could produce a bushel of corn on 0.85 pound of nitrogen if the season cooperates. If you’re applying all N preplant or in the fall, it could be 1.2 pounds of N per bushel. The system just won’t be as efficient.”

Figuring additional N needs

Jenkins developed a nitrogen management program, which he uses to help growers who sidedress know how much additional N to apply. It starts with soil tests, usually pulled about a week before the applications. Jenkins pulls 11 cores at two nearby locations, and then mixes them together before preparing a composite sample. He uses a frame with 11 holes so he can get cores both within rows and in row bulks.

The lab detects both nitrate and ammonium nitrogen. “Once we have results, we walk the grower through a process to help him determine how much more N to apply,” Jenkins says.

Jenkins uses calculations based on growing degree days that indicate when corn plants will reach different stages and when the most nitrogen will be needed. Once he knows how much N the soil should supply and how much more will be needed, he can determine sidedress recommendations.

“If it’s a sidedress system with corn in the V6 to V 7 stage and the yield goal is 210 bushels per acre, suppose results show we need another 60 pounds of N to finish the season,” Jenkins says. “Then we can look at soil type and environmental conditions. The grower may want to apply more or less than 60 pounds, based on what he thinks the crop will need.

“We help the grower zero in on what N needs are instead of just guessing. There have been situations where the test shows there will be an excess of nitrogen available. Then we often recommend cover crops to help scavenge N after the season.”

Jenkins’ exceptional work on nitrogen management helped him earn the Indiana Certified Crop Adviser of the Year award from the Indiana CCA group.