Throughout the growing season, strip-tillers have kept a close eye on their corn crop to assess if and when any late-season nitrogen (N) applications are warranted.

Whatever the situation, strip-tillers don’t want to see N go to waste. This was a point emphasized by Grand Marsh, Wis., farmers Eric and Megan Wallendal at the 2015 National Strip-Tillage Conference held recently in Iowa City, Iowa.

Farming 3,200 acres of row crops and vegetables, all under center pivot irrigation, the Wallendals’ soil types in central Wisconsin range from sandbox sand to light clay.

“We try to maintain a 1:1 ratio of N we apply vs. what we take off, but we know we can’t bank nitrogen year to year,” Eric says. “So we’ve got to manage our applications and still grow a high-yielding crop without degrading the ground.”

To take the guesswork out of in-season N applications, the Wallendals recently began using sets of 12-inch vertical sensing probes to measure soil moisture, electrical conductivity and temperature. The probes take sensor readings every 4 inches up to 48 inches deep.

The in-field sensors have become an input management tool the Wallendals use to better time nutrient application and measure plant uptake within their strip-till system.

“We need to know what our soils can hold,” Megan says. “We’re trying to ‘smart apply’ and if our heavier soils can only hold 20-30 units of N, we’re not going to apply 120. We’ll apply 20 or 30 at a time, see when the roots take up those nutrients instead of guessing, and based on crop stage make that next application when needed.”

In 2014, the Wallendals averaged between 250-270 bushels per acre for strip-tilled forage corn, applying about 260 units of N per acre.

The moisture probes have also allowed them to reduce water application costs by about 20% because they can incorporate the sensor outputs into their variable-rate irrigation program.

But another goal with the probes is to proactively plan for any forthcoming N application rules.

“The reason why we’re going through this effort to correctly apply our N, utilize strip-till and variable-rate technology is because we know there are going to be changes coming with application of fertilizer,” Megan says. “It’s going to impact us and we want to get ahead of the curve smartly and correctly.”

How are you measuring nutrient uptake to improve application efficiency in your strip-till operation? Share your story with me at (262) 777-2441, or send me an e-mail at