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Precision nitrogen application program catching on in Iowa

Precision nitrogen management, a set of tools designed to help corn farmers determine actual nutrient levels in their soils and adjust fertilizer applications more precisely to the needs of the crop, is gaining momentum in Iowa’s corn fields. Just ask Emily Ewoldt.

Ewoldt, who in May launched a new position at New Century FS to promote the N-WATCH nitrogen management program, has found a very receptive audience. So far, she’s signed up more than 60 growers in the N-WATCH, far exceeding the goal of the east-central Iowa farm cooperative.

"We think this a great program, and we are glad more growers are getting involved in it," Ewoldt said last week. "The growers we are working with definitely want to have more precise information."

Don Stratmann, agronomy de­­partment manager for Grinnell-based New Century, said the popularity of N-WATCH reflects farmers’ changing attitudes about fertilizer applications. As farmers’ emphasize precision, efficiency and environmental stewardship, they want to manage nitrogen as a system to apply the right amount, he said.

"They want to be precise with their nitrogen applications now as a way to limit input costs and reduce the potential for nutrient losses that can hurt the environment," Stratmann said. "They want to spoon-feed the crop, so they need to have better information on how much nitrogen is in their soil at different times in the growing season."

Farmers see the cost of the N-WATCH program, at $250 per year, as a very good investment in nitrogen management, Stratmann said.

Growmark FS calls the overall program to manage nitrogen as a system its "MOM" program, Ewoldt said. That program works to maximize nutrient utilization, optimize yield potential and minimize the impact on the environment.

Managing nitrogen

N-WATCH, designed by the Illinois Council of Best Management Practices, is a big part of improving farmers’ understanding of how their nutrient management program works, said Ewoldt, who grew up on a farm near Clutier and graduated from Iowa State University last spring. She works out of New Century’s Toledo location and manages the N- WATCH program across New Century’s entire territory in east-central Iowa.

N-WATCH is an educational tool using a system of soil probes taken in the same part of a field periodically throughout the growing season that’s a key part of its nitrogen management system. It’s not a nitrogen recommendation system, but is designed to help farmers and crop specialists build a knowledge base on the amount of nitrogen in the soil from after harvest through the corn-tasseling period.

The periodic tracking also helps show how the nutrient moves in the top 2 feet of soil.

In the N-WATCH system, Ewoldt works with clients to locate a spot in the field that is both representative and easy to access. Ewoldt marks that spot with a GPS system to make sure she can find it throughout the growing season.

Then, using a 30-inch wooden template that fits between two corn rows, Ewoldt and another New Century employee, Garrett Hoskey, take 11 core soil samples at a 12-inch depth and at a 24-inch depth.

Those samples are shipped to a laboratory in Ames, which analyzes them and emails results back to Ewoldt, usually in about 48 hours.

Setting a baseline

With the fall harvest in full swing, Ewoldt is busy taking soil probes in newly-harvested fields to get baseline nitrogen levels. "We want to know what levels of nitrogen are still in the soil after the crop has been harvested."

At planting time next spring, Ewoldt will probe the field again to gauge the amount of nitrogen available to the crop. Then she will continue to probe approximately every two weeks until the corn-tasseling period.

By analyzing those soil samples, Ewoldt and the farmer can track nitrogen amounts and how it is moving through the soil profile. They can also determine what form the nitrogen is in the soil and the applications needed.

System nitrogen management emphasizes making applications in smaller, more targeted segments, Ewoldt said. Farmers usually apply a base portion in the fall and another at planting time, she said. Then, depending on the crop needs, a third application may be required just before the crop tassels, Ewoldt said.

"The crop may need it, and it may not, and the N-WATCH testing will help us determine if it’s necessary," Ewoldt said.

The N-WATCH program, Ewoldt said, also helps farmers adhere to the industry-wide 4R approach to fertilizing, which emphasizes the right source, the right rate, the right time and the right place. It’s part of a range of practices, such as cover crops and nitrogen stabilizers, which are designed to improve nutrient utilization and reduce nutrient losses, she said.

"It really helps farmers know how much nitrogen is in their fields," Ewoldt said. "And that helps cut down over-applications and loss."



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