Submitted to: ASA-CSSA-SSSA Annual Meeting Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 7/28/2014
Publication Date: N/A
Technical Abstract: Hydrothermally carbonizing surplus animal manures from concentrated animal feeding operations (CAFOs) may become a viable manure management alternative. Hydrothermal carbonization (HTC) not only provides environmentally acceptable manure treatment, but it may also bring potential income revenues to farmers from producing nutrient-rich hydrochar. Emerging compounds, such as pharmaceuticals, personal care products, and endocrine disrupting compounds posing significant environmental concerns in animal wastes, landfills, and wastewater may be thermally degraded/transformed under autoclaving conditions of HTC. Although there exist numerous research studies in the literature on soil and environmental applications using plant-based biochar made from traditional dry pyrolysis (hereafter referred as pyrochar), a very few such studies exist for hydrochar made from hydrothermally carbonizing animal manures. The objective of this study is to investigate greenhouse gas emission and groundwater pollution potentials of the swine hydrochar when used as a soil amendment. Swine hydrochar was prepared by hydrothermally carbonizing the swine solids at 250 degree Celsius for 20 hours. Some of the hydrochars were washed with 200 millilitre acetone for 2 hours in order to remove labile compounds accumulated on the hydrochar surface. Hydrochar or pyrochar was mixed with a 50/50 mixture of Norfolk Ap and E horizon at a rate of 20 gram per kilogram. Sufficient deionized H20 was added periodically so that each pot would be maintained at 10 % moisture content (w/w). Triplicate pots containing soil without biochar served as controls. During the incubation periods of 42 to 127 days, greenhouse gas (carbon dioxide and nitrous oxide) emission fluxes were measured by nonlinearly regressing time-series headspace gas concentrations. Mehlich 1 extraction of the initial soils amended with hydrochar showed significant increase in nutrients such as potassium, phosphorous, calcium, magnesium, zinc, and manganese. Surprisingly, the hyrochar-amended soils leached very little of these nutrients probably due to complex surface functionalities binding these nutrients. Addition of swine solid hydrochar increased soil CO2 emission; however, N2O emission was repressed.