Co-composted biochar field trial (corn harvest)
Supported by the Southern SARE On-Farm Research program, this project is testing the use of biochar in local farm fields to better understand its effects on soil health and crop production. With support from the Sustainable Technology and the Built Environment department’s biochar class, the Nexus team built three compost bins at Springhouse Farm in September 2024. One bin contained no biochar, one included commercial loblolly pine biochar, and the third used farm-made biochar from mixed hardwood. Each bin was filled with a 5:3 mix of food scraps from the university dining hall and hardwood chips, with biochar making up about 9% of the total mixture in the two biochar treatments.
The finished compost was screened in May 2025 and applied to sixteen trial plots at Kornecopia Farm, with four replicates each of four treatments: no amendment, compost only, compost + commercial biochar, and compost + farm-made biochar. Temptress sweet corn was sown in June and harvested in August.
While soil and biomass analyses are still underway, we have begun reviewing field data from the first harvest (plant height, ear weight, length, defect tip length, and marketability). As expected, strong effects are unlikely in the first year, but preliminary results suggest that the average weight of marketable corn ears followed this order: compost only > farm-made biochar + compost > commercial biochar + compost > no amendment.
We will continue to track soil nutrients and crop performance over the coming seasons to better understand the long-term impacts of co-composted biochar.
Biochar & compost field trial plots (left); Mature corn plants before harvest (right)
Harvest day: students recording corn year traits
Slaughterhouse waste composting with biochar
This project, supported by the NCDA-BRI grant, investigates the effects of co-composting slaughterhouse waste with biochar. The Nexus team visited and toured the Wilkes Abattoir Compost facility in June with owner and operator Seth Church. Seth Church’s operation was funded by the NCDA and produces a 10/10/10 NPK fertilizer using slaughterhouse waste as the primary nitrogen feedstock. Seth notes that the animal bones toward the periphery of the compost pile do not break down as easily as those toward the center.
The purpose of this project is to monitor temperature and CO2 flux in two compost piles and note any differences. One pile was inoculated with 5% biochar by volume, while the other was left alone to represent the compost produced at Seth Church’s operation. Approximately 2500 lbs of the premixed offal and carbon was composted in our two aerated static compost piles (ASPs) at a volume of one cubic yard each. By monitoring temperature and CO2 flux throughout the composting process, it should be possible to understand if the biochar has an effect on the composting process.
The premixed compost was found to be quite dense, so we are currently replicating the experiment using biochar that was graded to approximately one-half inch in an attempt to increase the potential aeration benefits of using biochar. While data is still being compiled from the first attempt at this experiment conducted over the summer, preliminary results indicate that the compost pile with biochar reached the target temperature of 131 degrees F faster and sustained higher temperature for longer compared to the control pile.
After two months of composting in our ASP bins, the compost was trommel-screened for curing. Post compost bones will be pyrolyzed into bone char as part of another research project investigating phosphorous sustainability. Samples of the finished compost are being prepared for analysis at the NCDA soil testing laboratories.
Two-month-old compost in the ASP bin
Trommel-screened compost for curing
Bone char co-composting for phosphorus recycling
This project, supported by the STEPS program, explores the potential of animal bone—a renewable, phosphorus-rich resource—as an alternative to conventional phosphorus fertilizer. Unlike phosphate rock, which is non-renewable and contributes to runoff-driven eutrophication, bone char produced through pyrolysis offers a slow-release form of phosphorus that is pathogen-free and provides long-term retention in soils. Its porous structure can also help support microbial activity.
To evaluate this potential, we are co-composting three treatments in compost tumblers: (1) food waste and wood chips (control), (2) the same premix with bone char, and (3) premix with bone char plus phosphorus-solubilizing microbes (PSM). During the composting process, we are also monitoring temperature and CO₂ gas flux as indicators of microbial activity.
Once composting is complete, samples will be analyzed for composition, bioavailable phosphorus, and microbial activity. These results will help us understand how bone char influences phosphorus availability during composting, and whether PSM additions enhance phosphate solubilization.
Charred cow bone
SEM (scanning electron microscope) images of bone char (left) and biochar (right)