Measurements of N2O from composted organic wastes

The current atmospheric mixing ratio of nitrous oxide (N2O), a chemically significant trace gas, is increasing at a rate of 0.25-0.31% yr(-1), apparently well correlated with human activity. Better quantification of all N2O sources is required in efforts to stabilize this rate of increase. N2O emissions from the composting of wastewater sludge and livestock wastes were measured during 1993 and 1994 using enclosure methods. Static chambers were placed on the surface of the compost piles, and N2O mixing ratios within the chamber headspace were measured over time from which fluxes were calculated. The flux measurements resulted in mass-based emission factors of 0.7 g of N2O (dry kg)(-1) and 0.5 g of N2O (dry kg)(-1) for the sludge compost and the livestock waste compost, respectively. The derived emission factors were used in conjunction with recent waste generation and disposal statistics to estimate potential global N2O emissions from the treatment of organic wastes. Livestock waste treatment appears to hold the greatest N2O potential with estimated global emissions of 1.2 x 10(12) g of N2O yr(-1).