Manure Manager

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The proof is in the planting

Working to prove the benefits of biochar

June 18, 2024  by Ronda Payne

Biocar, derived from manure, is created through a process known as pylorization. All Images courtesy of University of Winsconsin

Biochar, the solid resulting from organic biomass material being heated at controlled, high temperatures with limited oxygen (pyrolysis), has long been hailed as a source of carbon and other nutrients for agricultural purposes. With its black, porous, lightweight appearance, it looks similar to charcoal, but without the fiery process to creation. 

Although biochar has been used as an agricultural amendment for more than 2,000 years, and has more than a few scientists, advocates, environmentalists, producers and suppliers behind it, it has yet to be incorporated into the modern, commercial-scale agricultural world as a regular treatment to advance soil health.

Researchers in Wisconsin are hoping they can move biochar to take its place in the sun, as well as fields and gardens, by proving the benefits our ancestors seemed to know inherently. 

Joseph Sanford, assistant professor in soil and crop sciences with the University of Wisconsin, Platteville has been working with a team to prove the efficacy of biochar in agricultural applications through two studies. 

Study #1: Studying plant health resulting from the use of biochar
“There’s not been a ton of biochar field studies,” he explains. “Particularly not in the Midwest. There’s been a lot of lab-based studies. This would be the only study that would look at making biochar from manure and then applying it to field plots and then studying the health of plants.”

This first study, conducted at the Arlington Research Center in Arlington, WI, will explore the benefits to plants of biochar applications to the soil at various rates. All plots (including the control) will have manure applied to them and will look at biochar application of one ton per acre, 2.5 tons per acre and five tons per acre.

This is a large field trial and to Sanford’s knowledge, a similar study has yet to be conducted.

“We will look at ammonia emissions,” he says. “And throughout the year, will look at greenhouse gas emissions. At the end of the year, we’ll look at yield.”

Soil nutrient retention will also be explored. 

“We’re going to be looking at the soil throughout the year,” he says. “From the soil health perspective, what impacts are there?”

Fellow researcher, Rebecca Larson, associate professor in biological systems engineering with the University of Wisconsin, Madison, says biochar is one of the more promising developments in terms of carbon sequestration.

“Biochar has more longer-term potential for carbon sequestration that we think. How does that impact it when you apply it to the land?” she inquires. “How it reduces emissions during application.” 

By applying manure to all plots, the view of how biochar can be of benefit in manured-systems will be significant to dairy and housed-livestock operations. Granted, these farms would need to invest in the systems to make biochar, but if the results are promising, it may be worthwhile.

While this study is focused on manure-input biochar, the applications are potential opportunities for other industries looking at biochar as an output from their waste materials as well. 

“A lot of landscape companies and sawmills are looking into it,” says Sanford. “To manage their waste streams.”

In Platteville, his pilot biochar production system is about the size of a commercial refrigerator and allows the team to produce a greater amount of biochar than previous systems. This allows for the volumes needed for the field study. 

“We have been looking at the ability to look at manure as the biomass to put in the pyrolysis system,” says Larson “A lot of people have been looking at using wood chips.”

While biochar produced from wood biomass has been proven to improve soil’s ability to retain water, increase plant-available water content, reduce nitrogen leaching, improve nutrient retention and decrease pollution to groundwater, the same results have yet to be shown from manure-derived biochar.

Previous studies have shown that manure biochar generally increases crop yields. 

“You can’t do a yield trial in a lab,” she says. “Is [this study] going to have the same impact that was seen in these smaller scale studies?”

It is hoped that this study will bring the positive results anticipated from manure-derived biochar’s application in large crop production systems. 

Biocar, derived from manure, is created through a process known as pylorization.

Study #2: Studying biochar as a transportable fertilizer
The second study looks at how to take the benefits of manure-derived, biochar from manure-heavy regions into other areas where phosphorus is needed in the soil. 

“We’re looking at making biochar out of manure itself,” Sanford says. “Instead of composting or doing other treatments on it, converting it to biochar and getting that phosphorus elsewhere.”

There are a lot of manure applications and additional phosphorus in crop fields in high dairy and livestock operations like those in the Midwest.

Many fields don’t need additional phosphorus making disposal of it a challenge.

“Groups have been looking into this,” he says. “Moving the phosphorus out. When a material goes through pyrolysis, it doesn’t lose any phosphorus. It just becomes a much more concentrated phosphorus.”

The theory is that applying manure-derived biochar at a phosphorus application level should provide plants with the same available phosphorus.

This makes the phosphorus-rich biochar a benefit to regions outside of the areas that have had heavy manure applications. 

“In the field, does that relate to plant uptake and can we use it as a potential phosphorus fertilizer?” he questions. “We know we can densify it. Can we now use that as a fertilizer source. The idea would be to export that to further sources from the farm than you can with manure or compost.”

Markets, on-farm applications and potential for the future
Larson says part of the problem biochar has had in reaching mass appeal is that the markets aren’t yet created for acceptance of this new (to the modern agricultural world) amendment. The market is not developed enough to support the production of on-farm and mass amounts of commercial-scale production systems.

She says some are moving forward and are taking biomass products to sale, but this isn’t yet common. 

“I think the markets are still in development,” she says. “It looks like the USDA is getting some support. There is a possibility for carbon sequestration so there’s the possibility for some funding on that, that may be available. 

Maybe there’s a potential market here, because there’s some support.”

Just as compost needed to have its market developed, the same goes for biochar.

She feels the data already available shows there is some emission mitigation and improvement to soil health. 

“All the collective data show some potential,” she says. “There’s a lot of nuances that we’re trying to build upon and determine.”

So far, pyrolysis reactors have been on an industrial scale and costs are high. Small-scale systems (processing about 2,000 tons per year) start at about $1 million and operating costs vary dramatically based on a significant number of variable factors. 

Systems work best with solid biomass that has less than 30 per cent of moisture content so separation prior to starting the pyrolysis process is necessary. Fortunately, as Larson points out, this has an easy, readily available and relatively affordable solution. 

“The current way that we’re doing it is separated solid,” she says.

“We’re using a screw press. You could use a variety of different things. There’s tons of screw presses out there. That’s one of the most commonly integrated separation technologies. Even some of the smaller organic farms have crew presses.”

She says that while wet pyrolysis can be done, it takes a lot of energy. 

The 5,000-foot view of biochar
Ultimately, these studies are unlikely to burst biochar onto the scene of agricultural awareness, but they will definitely help bring more data and interest to the topic. There is a lot more ground to cover when it comes to biochar because the variable factors of inputs (wood, plant matter, poultry manure, cow manure, swine manure and more), temperature, speed of process and more make for a variety of potential uses. 

Each varied set of inputs can lead to a different application because of the properties of the resulting materials. 

“We’ve been looking at ways to get the technology to be more economical,” Larson says.

“There’s a whole bunch of potential ways to use biochar in different systems.”

The team is also looking at how it can prevent nitrate leaching. 

“Using it as filter strips. The run off from feed storage,” she says. “That proved very effective in reducing nutrients to leaching in those systems. We ran some other studies and some of those studies were looking at could we put biochar in manure storages, could we reduce ammonia losses. Could biochar maybe absorb that? All those different ways of looking at biochar.”

She says there is significant interest in taking biochar in numerous directions.

Using it as a filter, a fertilizer, field applications, adding it to feed and more. 

“We’ve been looking at different ways of using biochar,” she says. 

Not bad for a product that was initially seen as a bi-product While biochar is the solid that come from pyrolyzing, other outputs include syn-gas and bio-oil fuels that have been applied to heating and energy uses. 

“All biochars are different,” Larson says “You can make them all different. It changes the properties. It would make them useful in different ways.”

Biochar has a promising future in the world of agriculture, but it’s going to take proof, on-farm application and awareness to get there.

With researchers like Sanford and Larson continuing to explore the various uses of biochar, everything from farms and gardeners to environmentalists and agricultural businesses will be learning about the potential applications. •


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