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Use center pivots to spoon-feed N to your cornfields

After above-normal spring rain in 2011, Doug Ziemke of Waco noticed yellowing in several cornfields. Tissue samples verified his suspicion that some of his preplant nitrogen had leached below crop roots.

That prompted the York County farmer to equip two center pivots to apply nitrogen, the first time he had ever used his irrigation systems to do so. He made one pass with each pivot to apply 0.30 of an inch of water and the nitrogen solution. For 2012, he intends to apply less anhydrous ammonia preplant on these two circles and possibly a third one, and instead spoon-feed the remaining nitrogen by fertigation.

“I was real satisfied with the results in 2011,” he adds.

Practice used before

The practice of chemigation — the overall term for applying pesticides or fertilizers through center pivots — peaked in the 1980s and early 1990s when farmers treated for corn borer infestations. The practice subsided with the introduction of transgenic hybrids with Bt traits for corn borer control.

Richard Ferguson, University of Nebraska soils specialist, believes more farmers ought to consider applying nitrogen through pivots to spoon-feed N, especially since 80% of Nebraska’s 8 million irrigated acres is watered by sprinklers. “We should be taking more advantage of fertigation. We are in a good position in Nebraska to do so,” he says.

“It is an efficient method of supplying part of the nitrogen needed by the crop near the time of maximum nitrogen uptake,” Ferguson says. “It’s also a stewardship practice by preventing nitrate leaching to the groundwater.”

While it varies by hybrid, the most rapid period of uptake is between the eight-leaf stage and tasseling, a time when a steady supply is critical for optimum yield.

Certification training

Bill Kranz, UNL irrigation engineer who coordinates the chemigation certification training each year, has seen a moderate increase in the number of farmers or other operators the past two years taking the two- to three-hour course to become certified chemigation applicators.

The Upper Big Blue Natural Resources District, based in York, encourages use of fertigation, says Rod DeBuhr, district water department manager. Nebraska’s NRDs, under the 1987 Nebraska Chemigation Act, are charged with inspecting irrigation sysems that are equipped with several mandated safety components when applying pesticides or fertilizer.

Ziemke opted to have the United Farmers Co-op, based in York, do the actual chemigating through a new service it started in 2011 to foster use of fertigation. Eight of UFC’s employees became certified by taking the UNL course, eliminating the need for farmer/customers who sign on for the service to become certified themselves.

UFC built two mobile trailers, each of which carried a nitrogen tank, injector pump and a couple of safety components to the pivot site. And one of UFC’s employees certified in chemigation managed the actual fertigation application.

Farmers pay a fee for the service, and they also are responsible for purchasing the main check valve that prevents backflow from the pivot to the well in case of a system shutdown. Another component required of farmers is a simultaneous interlock system.

“When we frontload most of our nitrogen through preplant and starter, there are too many things we can’t control,” says Andy Bowman of UFC. “Fertigation is one of the solutions to this problem.”

UNL certifies, NRDs inspect

Nebraska passed the state Chemigation Act in 1987 to prevent backflow of chemicals or fertilizers from the irrigation system to groundwater in case of a breakdown.

The Nebraska Department of Environmental Quality oversees the program. The agency contracts with UNL to conduct certification training for chemigation operators, which can be farmers, one or more of their employees, a crop consultant or an agronomist.

A test at the end of the session must be passed. Certification lasts for four years. A certified chemigator submits the paperwork to his or her natural resources district, which then issues the permit. NRDs, under the law, also inspect chemigation setups.

Dates and locations for training sessions this year had not been finalized at press time. Contact your local Extension educator or Bill Kranz, UNL Extension, at 402-584-3857. His email address is wkranz1@unl.edu.

Try online training

The University of Nebraska-Lincoln Extension is set to unveil an Internet-based chemigation training program later this month.

UNL’s Bill Kranz says the Web-based training program is intended for those needing to recertify, not for those becoming certified for the first time.

“The training program covers all the information presented at the in-person training sessions,” he says. “You will be able to access the new training program from anywhere Internet access is available.”

The training consists of a series of modules which contain text, video clips and calculators to provide chemigators with the necessary information to employ chemigation in an effective, efficient and environmentally safe manner while safeguarding farm workers involved in chemigation, Kranz says. The training is self-paced and can be done over several visits to the website.

The online program, like the in-person sessions, requires taking a test after completing the training. However, the tests aren’t available in the same program. Instead, those finishing the online training must go to one of 16 Extension office locations in Nebraska to take the test.

Those testing sites for online testing and contact numbers are:

Alliance, 308-762-5616

Columbus, 402-563-4901

Fremont, 402-727-2775

Grand Island, 308-385-5088

Holdrege, 308-995-4222

Imperial, 308-882-4731

McCook, 308-345-3390

Norfolk, 402-370-4040

North Platte, 308-532-2683

O’Neill, 402-336-2760

Ord, 308-728-5071

Scottsbluff, 308-632-1480

Sidney, 308-254-4455

Valentine, 402-376-1850

Wilbur, 402-821-2151

York, 402-362-5508

Again, you can contact Kranz at 402-584-3857 or your county Extension educator.

Once the program has been released, producers will be able to go to water.unl.edu/web/cropswater/chemigation. Once there, you’ll find links to “chemigation course directions,” where you can sign in, and then “proceed to chemigation training.”


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INSPECTION: Jon Reiter, a former employee of the Upper Big Blue NRD, inspects a chemigation check valve as part of the district’s state requirement to check up on pivot’s that are equipped to apply pesticides or fertilizers.
Upper Big Blue NRD photo

This article published in the February, 2012 edition of NEBRASKA FARMER.

All rights reserved. Copyright Farm Progress Cos. 2012.