Biochar Diminishes Nitrous Oxide and Nitrate Leaching from Diverse Nutrient Sources

Manure generated by intensive livestock operations poses potential ecological risk in the form of water pollution and greenhouse gas emission. To assess the impact of biochar on coarse-textured soils under contrasting nutrient management regimes, a 55-d incubation was conducted using unplanted soil columns amended with manure, slurry, or fertilizer (plus unamended control), each with or without biochar applied at 2% soil mass (dry weight basis). Under repeated leaching, the cumulative N2O emission from the columns was significantly affected by the presence of biochar (p < 0.0001), although these data were not normally distributed. Results indicated that the biochar-amended soils emitted significantly less N2O than their unamended counterparts, with the exception of manure-amended soils. The presence of biochar increased the pH of column leachate by 0.08 to 1.70 and significantly decreased the cumulative amount of mineral N leached from the soil. The presence of biochar significantly increased the amount of PO43--P in soil leachate, but there was no significant difference between the means for any of the amendments used on their own relative to their biochar-amended counterparts. The data demonstrate that biochar could potentially aid in the mitigation of N2O emissions from certain soils and in N loss in leachate from soil amended with slurry, manure, or fertilizer used in livestock systems.