To understand the apparent discrepancy between N losses and measured fluxes, it is important to consider the method by which the gas flux measurements were made, which involved premixing of the samples. Under these conditions, the apparent driving forces for emission were the N concentration and pH, and the daily loss of initial TAN was as reported above. On the contrary, N losses estimated by mass balance were obtained by sampling the manure stored in the vessels, which were mixed only during the sampling days.