Loss of ammonia in soil and of urea-autoclaved and treated organic residues

Abstract

Effect of adding organic residues to soil in ammonia losses by volatilization due to urea application is evaluated, together with autoclaving at 120°C, at 1 atm, during two hours. Samples of Ap surface of structured eutrophic dark red latisol (Rhodic Kanhapludalf, clay texture) from the municipality of Piracicaba SP Brazil, were used. Autoclaving delayed the peak of losses and increased loss of ammonia up to 56%. Autoclaving did not delete the stimulating effect of organic residues on the volatilization of ammonia (NH₃). Autoclaving partially decreased the effect on peat and enhanced ammonia loss in cattle manure and house garbage. Autoclaving increased pH of soil and of cattle manure; slight changes in pH also occurred in other residues