Biochar stability in a highly weathered sandy soil under four years of continuous corn production
2021
Novak, Jeffrey Michael | Watts, Donald W. | Sigua, Gilbert C. | Myers, William T. | Ducey, Thomas F. | Rushmiller, Hannah Claire
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.
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