Greenhouse Gas Emission and Groundwater Pollution Potentials of Soils Amended With Different Swine Biochars.

The objective of this research was to study the greenhouse gas emission and groundwater pollution potentials of the soils amended with various biochars using different biomass feedstocks and thermal processing conditions. Triplicate sets of small pots were designed; control soil consisting of Histisol, Entisol, and a 50/50 mixture of Norfolk Ap and E horizon. The amendments (5 to 20 g kg-1) consisted of raw swine solids, thermally carbonized swine solids at 620 oC (biochar), hydrothermally carbonized swine solids at 250 oC (hydrochar), and the mixtures of hydrochars made from sugar beet, bark, and swine solids. After the amendments were mixed into the soil, its moisture content was maintained gravimetrically at 10% (w w-1) by replenishing with D.I. H2O. Eighteen to 30 days after incubation, the pots were leached with 1.2 to 1.3 pore volumes of deionized H2O to simulate flushing. The leachates were collected and analyzed for the oxygen-demanding water quality parameter (COD), nutrients (N, P, K, Na), and heavy metals (Cd, Cr, Cu, Ni, Zn). Soil samples from the initial set up along with samples at incubation termination were analyzed for fertility. Some of the hydrochars after incubation will be analyaed with a X-ray photoelectron spectroscopy (XPS) to determine the elemental composition on the incubated hydrochar surface. During the incubation period, greenhouse gas (CO2 and N2O) emissions from each pot of soil were measured. Data on CO2 and N2O emissions, water quality of leachates, and surface elemental composition changes from the incubation study will be presented at the meeting.