INJECTION OF PIG SLURRY AND ITS EFFECTS ON DYNAMICS OF NITROGEN AND CARBON IN A LOAMY SOIL UNDER LABORATORY CONDITIONS

Dynamics of nitrogen (N) and carbon (C) were investigated in a loamy s oil amended or injected with pig slurry. Treatments were with or witho ut acetylene C2H2 (which is assumed to inhibit reduction of nitrous ox ide (N2O) to dinitrogen (N-2), and soil cores were conditioned for 15 days at 25 degrees C while pH, production of CO2 and N2O, ammonia (NH3 ) emission and (nitrate) (NO3-) and (ammonium) (NH4+) concentrations w ere monitored. There was no significant difference in CO2 production b etween the injected and surface applied pig slurry treatments, and wit hin 15 days ca. 5% of the C applied had been mineralized, if no primin g effect was assumed. Neither the production of N2O nor the total gase ous production of the denitrification process (N2O plus N-2) were affe cted by the way the pig slurry was added to the soil. NH3 volatilizati on, however, decreased by 90% when pig slurry was injected. The additi on of C2H2 significantly increased the CO2 production and the concentr ation of NH4+, but significantly decreased the concentration of NO3-. It was concluded that the injection of pig slurry to a dry soil was an acceptable alternative to its application to the soil surface, as not only was NH3 volatilization reduced, but the production of N2O and N- 2 through denitrification was not stimulated. It is also suggested tha t the composition of the organic C fraction in the pig slurry, most li kely the concentration of fatty acids, had an important effect on the dynamics of N and C in the soil.