|Watts, Donald - Don|
|Myers, William - Tillman|
Submitted to: Energies
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/24/2021
Publication Date: 9/27/2021
Citation: Novak, J.M., Watts, D.W., Sigua, G.C., Myers Jr, W.T., Ducey, T.F., Rushmiller, H.C. 2021. Biochar stability in a highly weathered sandy soil under four years of continuous corn production. Energies [MDPI]. 14:6157. https://doi.org/10.3390/en14196157.
Interpretive Summary: Scientists concerned with determining suitable methods for reducing atmospheric carbon dioxide (CO2) gas concentrations are examining soil-based management practices that are linked to gains in soil organic carbon (SOC) sequestration. One of these potential strategies is the use of biochar as a soil amendment. Since biochar is a C-enriched material, its application to soil is known to increase SOC contents. For biochars to have a long-term impact at off-setting atmospheric CO2 concentrations, however, it has been suggested that the material should remain in soils for more than a hundred years. There are few field studies that have examined biochar stability in soils. We conducted a field-based assessment of pine chip biochar and poultry litter biochar under 4-years of continuous corn production using typical reduced tillage and agronomic practices for the Southeastern USA Coastal Plain region. By sampling soils treated with these two biochar types, we found that 80 to 90% of the original pine chip and poultry litter biochar was still accountable in the sandy topsoil (0-5 and 5-10 centimeters deep) after 4-years of continuous corn production. Based on this stability estimate, either pine chip or poultry litter biochar can be used as a C sequestration agent and serve as a tool to reduce atmospheric CO2 gas concentrations.
Technical Abstract: Biochar is being considered a climate change mitigation tool by increasing soil organic carbon contents (SOC), however, questions remain concerning its longevity in soil. We applied 30,000 kilogram per hectare (kg ha-1) of biochars to plots containing a Goldsboro sandy loam (Fine-loamy, siliceous, sub-active, thermic Aquic Paleudults) and then physically disked all plots. Thereafter, the plots were managed under 4 years (Y) of continuous corn (Zea Mays, L.). Annually, incremental soil along with corresponding bulk density samples were collected and SOC concentrations were measured in topsoil (down to 23-cm). The biochars were produced from Lodgepole pine (Pinus contorta) chip (PC) and Poultry litter (PL) feedstocks. An untreated Goldsboro soil (0 biochar) served as a control. After four years, SOC contents in the biochar treated plots were highest in the top 0-5 and 5-10 centimeters (cm) depth suggesting minimal deeper movement. Declines in SOC contents varied with depth and biochar type. After correction for SOC declines in controls, PL biochar treated soil had a similar decline in SOC (7.9 to 10.3%) contents. In contrast, the largest percent SOC content decline (20.2%) occurred in 0-5 cm deep topsoil treated with PC biochar. Our results suggest that PC biochar had less stability in the Goldsboro soil than PL biochar after 4 years of corn grain production.