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Serving: NE
manure being applied by sprayer in field
WASTE TO WORTH: Nebraska Extension biological systems engineer Rick Koelsch says that we shouldn't associate the word "waste" with manure.

What is manure worth to soil?

Nebraska Extension biological systems engineer speaks about how farmers can maximize this resource.

It doesn't matter what size of animal feeding operation, manure can be viewed as a product of value.

Rick Koelsch, Nebraska Extension biological systems engineer, says that manure presents a mixed bag of positive effects and challenges. In a recent USDA Natural Resources Conservation Service webinar, Koelsch talked about finding a balance to efficiently use manure resources.

"I don't even like to use the term 'waste.' Manure is not waste, but is a resource," Koelsch said. "Historically, we have recognized how valuable manure is. It was shipped from country to country on sailing ships of old because of its soil building capability.”

"Our agricultural enterprises are biological systems," Koelsch added. "For biological systems to function well, they must recycle carbon and nutrients, the first key to stewardship."

No matter if an animal feeding operation is quite small or larger, with a larger land base, there needs to be a focus on recycling nutrients, he said.

"Increasingly, AFO and crop production systems are viewed separately," Koelsch said. "Feed, in this case, becomes a big input. For AFOs purchasing feeds, we still need to recycle nutrients, so we look at exporting manure, and how efficiently we recycle manure nutrients through our neighboring crop farms."

This is a critical point for any size of operation, no matter if the manure is recycled internally to crop systems within the operation or recycled through fields belonging to neighbors.

Koelsch said that the second key to stewardship is using locally produced nutrients before importing commercial fertilizers from outside the region. "It's the same with manure," he said. "We value nutrients gained from manure, legume crops or irrigation water as sources of locally produced nutrients over outside sources to help us protect water quality.”

"Looking at these keys helps farmers understand the value of manure and how to get peak value from manure," Koelsch said. "The way to do that is to be a good steward of water quality and to control the flow of nitrogen and phosphorus from the AFO." He suggested finding "win-win" opportunities for using manure by targeting fields where the manure will provide the greatest value.

Understanding the actual value of the manure requires looking at the fertility benefits coming from organic nitrogen, ammonium, phosphorus, potassium and micronutrients. Beef feedlot manure could be valued as low as $14 per ton and as high as $28 per ton, based on 2017 commercial fertilizer prices.

"Phosphorus has the greatest value in the lower estimate manure, with potassium and phosphorus having the greatest value in the higher estimate," Koelsch said. "But it is different with different manures.”

Swine slurry, for instance, would have a lower estimated value of $19 per ton, going as high as $39 per ton, with phosphorus and nitrogen being the largest contributors to the slurry's value.

"You would target different fields with different swine and beef manures to gain the maximum value," Koelsch said. "Understanding this is helping farmers to get the greatest value from their manure. This gives more of a chance it will be used as a resource and less of a chance the manure will be an environmental risk."

Koelsch suggested matching the soil tests, crop needs and the manure nutrient profile. The distance of the transport also factors into the value.

Some manure benefits are hard to quantify. "Manure changes the chemical composition of the soil, but it also improves the physical and biological properties," Koelsch said. "Changes occur more quickly than we think. Several properties like the physical properties can change within days to weeks after manure is applied."

Manure feeds microbial activity, too. "It serves as a food source for the microbes, so the output is the formation of soil aggregates," he said. "Infiltration goes up, so there is less runoff and erosion."

Studies in southeast Nebraska show an increase of macro-aggregates from the application of all manures, including beef and swine, as well as compost, compared with places where no manure was applied.

"Aggregates form quickly and persist throughout the crop season," Koelsch said.

Learn more by contacting Koelsch at rkoelsch1@unl.edu. You also may be interested in online resources about the economic value of manure at water.unl.edu/manure/manure-value.

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