While many Corn Belt no-tillers have suspected it for years, it took researchers at North Dakota State University to demonstrate how continuously no-tilled soils require less nitrogen.

What has taken place in regard to nitrogen recommendations for long-term no-tilled soils is unprecedented with these new North Dakota guidelines. And there’s no doubt this fertility research represents a major step forward in no-till fertilization.

Soil scientist Dave Franzen has determined that when it comes to growing corn, fields that have been in continuous no-till for over 6 years require 40 to 50 pounds less nitrogen per acre than conventionally tilled soils. These recommendations follow on the footsteps of earlier North Dakota work with spring wheat and durum that indicated a 50-pound-per-acre nitrogen credit for long-term no-till.

North Dakota is apparently the first land-grant school in the country to adjust soil fertility recommendations to account for the nitrogen-reducing benefits of no-tilling. Like is the case in many states, fertility recommendations for corn grown in North Dakota were based on data published 40 years ago.

“My inspiration for doing this work came from my first winter in North Dakota when some founders of the Manitoba-North Dakota Zero-Tillage Association came up to me during a social time at one of their meetings,” Franzen says. “They welcomed me to North Dakota and then told me that they didn’t follow the university recommendations for nitrogen anymore. They found they could decrease their nitrogen rate once a field had been in no-till for a series of years.

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