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A wet fall followed by freezing temperatures and heavy snowfall in areas may force some Iowa farmers to adjust how they apply manure to their fields — which could spell foul odors for some rural residents and a higher risk for runoff into waterways.

Manure waste typically is applied to fields before spring planting and after fall harvest. The preferred method is injection — equipment cuts a slot in the ground and liquid manure is applied directly into the field — to reduce the risk of runoff and get the most nutrients from the manure.

A delayed harvest, a rain-soaked fall, early freeze and heavy snowfall all add up to a difficult year for farmers with limited manure storage — forcing some into winter application, said Kenneth Hessenius, environmental program supervisor with the Iowa Department of Natural Resources Spencer field office.

Frozen ground cannot be cut for injection, which means manure must be sprayed onto the ground — resulting in lost nutrients and higher risk for runoff. In addition, sprayed manure sits in the open air and can be smelled for miles.

“Over the last 25 to 30 years, I think this is right up there as one of the most challenging fall application and crop removal seasons that we’ve had,” Hessenius said. “There’s no doubt in my mind there’s going to be more surface application than what we normally see.”

Daniel Andersen, associate professor in manure management and water quality with Iowa State University, said the transition from fall application to storage is normal, but this year’s conditions have offered limited opportunities to get manure out of storage and onto fields.

“Now we want to encourage people to do those best practices,” Andersen said.

That means applying manure when and where possible before state-mandated prohibitions on application take effect.

Andersen said farmers can minimize the risk of nutrient loss by applying manure to drier locations, increasing setback distances from waterways and being mindful of the forecast to avoid applying manure before the possibility of precipitation.

Farmers also should try to avoid applying manure to snow-covered fields, to prevent runoff.

Such practices can help keep nutrients in fields and out of Iowa waterways. But Andersen noted they don’t eliminate the risk of runoff entirely.

Winter rules

As winter further envelopes the state, rules and restrictions on manure application begin to take effect.

Iowa’s winter manure application rules — which limit how and where manure can by spread on fields — kick in later this month.

From Dec. 21 through April 1, liquid manure application is prohibited on snow- or ice-covered ground unless manure can be injected properly. Starting Feb. 1, liquid manure application is prohibited on frozen ground.

Manure still can be applied in an emergency during those prohibitions, but doing so requires a waiver from the Iowa Department of Natural Resources. Added restrictions, such as no application within proximity of water sources, are enforced during emergency situations.

The DNR also issues waivers for surface manure application when injection isn’t possible due to frozen ground. Such facilities claimed points for manure application in their required master matrix review process — the state’s main regulatory system for animal confinements.

Hessenius said this is the first year the department has logged emergency waivers, adding that the number of waivers appears to be up from previous years.

“I suspect in most of Northern Iowa we’ve got some pretty frozen ground, at least in the top few inches, which is going to eliminate the ability to inject manure,” Hessenius said.

As of Monday, Iowa had recorded 79 emergency waivers for surface manure application. Of those, all but five were requested in the Department of Natural Resources’ field offices 2 and 3, which cover the state’s north-central and northwestern counties.

For Jason Russell, who operates two confinements with a capacity of more than 14,000 hogs in northern Linn County, his manure storage space likely is big enough to handle the winter.

Russell said his operation produces as much as four million to five million gallons of manure a year, so proper application is important.

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“Ideally, you want to be able to inject it,” he said.

“It’s best to plan ahead ..., we’re always trying to mitigate the risk. I don’t want to risk wasting manure or making the neighbors mad from the smell.”

Lost nitrogen

In early 2016, the not-for-profit Iowa Policy Project argued, in a “Winter Manure Application: Waste of a Resource” report, that Iowa’s winter manure regulations are harmful to the environment and economically wasteful.

The report, which looked at two years of nitrogen lost in surface runoff at different times in the year, found that 8.2 percent of nitrogen was lost during early winter manure applications on cornfields, compared to only 1.2 percent lost in the spring.

More than 22 percent of nitrogen was lost to runoff during late winter manure applications.

Nitrogen runoff in manure application has been linked to fish kills, beach closures and contamination issues in drinking water, as well as environmental concerns where the Mississippi River pours into the Gulf of Mexico.

David Osterberg, who founded the Iowa Policy Project in 2001, said little has changed in Iowa’s manure application rules since he authored the 2016 report.

“There are a whole lot of really good farmers out there who are thinking about the environment as well as their pocketbook, but a bunch of them don’t,” he said.

But while farmers may want to eliminate runoff to ensure the most nutrients for their crops or to prevent environmental harm, Osterberg said the state lacks disincentives for runoff, and doing so would add a level of accountability.

“There ought to be more of a downside when things don’t work well and all of a sudden you’ve done a lot of polluting,” Osterberg said.

“And it ought to be you take that possibility into consideration, in the way you’re doing your operation. But you don’t have to because Iowa won’t make you.”

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