Attendees inspect equipment at the North American Manure Expo on July 14, 2022, in Chambersburg, Pa.

Melissa Wilson, a University of Minnesota nutrient management specialist, speaks at the North American Manure Expo on July 14, 2022, in Chambersburg, Pa.

Attendees inspect equipment at the North American Manure Expo on July 14, 2022, in Chambersburg, Pa.

CHAMBERSBURG, Pa. — Farmers who sidedress corn typically use purchased nitrogen fertilizer, but liquid manure could be a good alternative.

Melissa Wilson, a nutrient specialist from the University of Minnesota, explained why in a July 14 talk at the North American Manure Expo.

Sidedressing in general is appealing because it delivers the nutrients when the crop needs them.

It also relieves some pressure to apply manure before or after a crop. In the Upper Midwest, those traditional windows of opportunities have been shrinking because of increasingly wet weather, Wilson said.

Minnesota has the additional challenge that many hog barns were built in the 1970s, when pigs were smaller and took longer to grow than they do today.

“A lot of the storages don’t last for a whole year anymore,” said Wilson, a Pennsylvania native.

A six-year research project in Ohio found that fields sidedressed with strips of manure produced an average yield 17 bushels per acre greater than fields sidedressed with urea ammonium nitrate.

In her first year of testing in Minnesota, Wilson found no statistical difference between sidedressing manufactured fertilizer and sidedressing manure via dragline.

In the study’s second year, the manure treatment underperformed the purchased fertilizer. Wilson said that was probably because the manure applicator mistakenly applied 90 pounds of nitrogen per acre instead of 140.

Now that manure sidedressing appeared to work — assuming one followed the directions — Wilson had to determine how much damage the corn could tolerate from a drag hose being pulled over it.

Wilson filled a manure hose with water and dragged it over corn at varying stages of growth.

She pulled the hose down and back across the field; in a commercial setting, most corn would only be dragged over once, but Wilson wanted to test the worst-case scenario.

The immediate aftermath was not pretty. The corn was battered, and in some places the crop appeared to be gone.

“I was like, wow, that was the stupidest thing we’ve ever done,” Wilson said.

To her relief, when she came back a week later, the corn treated before the V5 growth stage was starting to come back.

The V5 growth stage is about when corn’s growth point rises above the soil surface and becomes vulnerable to the dragline.

A corn variety with a relatively high risk of green snap — breakage during late-season wind storms — saw significant yield reductions from dragline damage starting at the V5 stage.

Curiously, yield reductions started earlier, at the V4 stage, in a hardier variety with a lower risk of green snap.

Wilson thinks that a stalk least likely to break in a storm will be thick. A drag hose might break such a stout stalk, while a thinner plant might only bend, Wilson said.

To be on the safe side, Wilson recommended sidedressing with a dragline before the V4 growth stage.

The manure expo was held July 13-14 at a recently harvested small grain field next to Interstate 81 in Chambersburg.

The expo included a trade show, tours and demonstrations. It was last held in the area in 2015.

Melissa Wilson, a University of Minnesota nutrient management specialist, speaks at the North American Manure Expo on July 14, 2022, in Chambersburg, Pa.

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Phil Gruber is the news editor at Lancaster Farming. He can be reached at 717-721-4427 or pgruber@lancasterfarming.com. Follow him @PhilLancFarming on Twitter.

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