Carbon and better soil


Applying char to research plot
Char is spread onto research plots at the Mitchell Ag Lab, several miles north of the University of Nebraska Panhandle Research and Extension Center. The fine power is spread with a golf-course spreader.
UNL studying whether char from sugarbeet plants will improve soil

By Dave Ostdiek, Communications Associate
Panhandle Research and Extension Center

Scientists from the University of Nebraska-Lincoln (UNL) have begun a multi-year study into whether high-carbon char, a fine, powdery coal dust left over from the processing of sugarbeets, will improve the soil if applied to farmers’ fields.

Western Sugar Cooperative produces 35,000 tons of char each year as a byproduct at its sugar manufacturing plant in Scottsbluff. Western Sugar has plants and other storage and delivery facilities for sugarbeets in Nebraska, Wyoming, Colorado and Montana.

Researchers from UNL’s Panhandle Research and Extension Center and also the Lincoln campus of UNL’s Institute of Agriculture and Natural Resources are beginning a three-year study in which they will apply high-carbon char to several research plots near Scottsbluff. The char will be applied once at several different rates (ranging from 0 up to 25 tons per acre), incorporated into the soil, and crops will be planted in a four-year rotation that includes sugarbeets, corn and dry edible beans.

Char closeup
Before it is spread onto fields, char is screened, eliminating larger particles and leaving a finer powder.

The research team will measure crop yields as well as changes in the soil physical properties (infiltration, crusting, water holding capacity, density, color), and chemical properties (carbon, pH, salinity and soil nutrient levels).

The potential soil-quality benefits include an increase in organic matter and soil carbon. Higher concentrations of carbon in the soil reduce crusting, rapid soil-surface drying and compaction, and improve soil structure, water infiltration, water-holding capacity, and microbial activity. Decades of crop production have depleted organic matter and soil carbon from many fields in western Nebraska, according to Dr. Gary Hergert, retired soils specialist at the Panhandle Center, who is advising the research.

The project has the potential turn into a long-term effort involving generations of scientists, much like the adjacent Knorr-Holden corn plots, established 114 years ago in 1912.

It is one of a very few, and possibly the only, large field-plot-scale project in the United States to study the effects of biochar, according to Hergert.

For Hergert, the biochar project came about as the result of a convergence of several factors. Several years ago he did research into treating soil with another Western Sugar byproduct, precipitated calcium carbonate (PCC for short).

PCC is lime left over from the process of extracting pure sugar crystals from the raw juice removed from sugarbeets. In the earlier project, Hergert and other scientists at the Panhandle Center applied PCC to 30 fields in Nebraska, Colorado and Wyoming. The PCC added some nutrients but did not have a significant positive effect on soils. It also did not have any negative effects on the soil or crops.

Plots are still being monitored to see if the PCC helps reduce Aphanomyces, a sugarbeet disease. Research in other areas has shown a reduction in this disease.

But another byproduct produced at Western Sugar factories is high-carbon char. According to Hergert, the plants at Scottsbluff and Fort Morgan, Colo., generate 35,000 tons per year of the sooty powder from coal that is burned incompletely to heat the lime for the sugar-refining process.

Char is carbon-based, and numerous research papers show that carbon can be used to enhance soils, Hergert said. Additionally, charcoal has been used to improve soils in the Amazon River basin in South America for 2,500 years or more. The natives of the region would create charcoal and incorporate it into small plots of land.

Coincidentally, Hergert had been hearing about biochar and its potential for several years at agronomic society meetings.

Research into biofuel alternatives to ethanol had been on the increase since growth in ethanol was capped in the new Renewable Fuel Standard by the Energy Independence and Security Act of 2007 (EISA). The new Renewable Fuel Standard capped production of corn ethanol, but called for increases in other types of biofuels that had a greater reduction in greenhouse gases. Hergert said this led to the expectation that other biofuel sources, such as cellulosic materials like irrigated grasses, would grow in importance.

One potential ethanol addition is second-generation biofuels created by pyrolysis, the heating of cellulosic substances to create an oil-like substance. Biochar is a leftover remain of pyrolysis. Research conducted elsewhere on its agronomic effects has been on small-scale, greenhouse-size plots, due to lack of federal funding and congressional follow-through that would support second-generation biofuels, according to Hergert.

To date there are no commercial-scale pyrolysis plants in the United Sates. Little, if any, of the research has been conducted on field plots.

But there are large piles of char, which is very similar to the biochar, near the region’s beet sugar refineries. And there are field plots at the Panhandle Research and Extension Center. And now, thanks to funding from the Western Sugar Cooperative Research Committee, there is a multi-year project to see if char applications will benefit the soil.

Humberto Blanco, Associate Professor of Soil Management in the UNL Agronomy and Horticulture Department, is the principal investigator. Blanco, in Lincoln, has been collecting soil samples measuring the soil’s physical properties.

In addition to Hergert, other project members include several faculty and staff at the Panhandle Center: Research Technicians Rex Nielsen and Les Kampbell; Dryland Cropping Systems Specialist Cody Creech; Integrated Weed Management Specialist Nevin Lawrence; and Associate Director Jim Schild. Steve Godby and David Reichert from Western Sugar are also working on the project.

In addition to the irrigated plots at Mitchell, char is being applied on dryland research plots at the High Plains Ag Lab under the supervision of Creech, the dryland cropping specialist.

The project is in its first year and is scheduled to continue through 2018. But positive results and funding have the potential to transform it into a long-term effort, if it is determined that more time and funds will help achieve the project’s goals.

Getting the char from Wester Sugar’s piles onto research plots takes several steps. According to Hergert, the piled char is first hauled away by contractor Paul Reed, who is donating screening services to sort the material into different particle sizes. Reed uses the larger particles for road aggregate, and the finer particles are used for the UNL research project.

The UNL researchers truck the char to the plots at the Mitchell Agricultural Laboratory north of Scottsbluff, where it is applied with a golf-course green sander. Finding an implement to apply char was a challenge, Hergert notes. Manure and fertilizer spreaders do not work, but the sand spreader does, as long as the char is screened to eliminate larger pebbles out when it is loaded into the spreader.

Hergert said Nielsen has worked out many of the logistics of obtaining the char and applying it to the field.

Hergert hopes the Western Sugar funding will turn out to be seed funding that could be leveraged into larger federal grants to study the potential of char. Those efforts would need to be pursued by the younger faculty now on board at the Panhandle Center.

The study could stretch over many years, much like the century of research that has occurred at the Knorr-Holden plot into continuous corn production and application of livestock manure.

The char has current commercial use as a road material and the potential future use for improving soil properties and crop production could point to future demand for the byproduct, Hergert said.

“If it takes off, the demand will be much greater than the supply.”