Water-manure interactions on ammonia volatilization

Abstract

The integrated horizontal flux method was used to determine NH₃ volatilization from surface-applied swine manure (Sus scrofa domesticus). This method allows simple NH₃ flux estimates to be made from small source plots based on a measurement of windspeed and NH₃ concentration at a single sampling height. Simultaneous flux estimates were performed to indicate the NH₃ loss as affected by light rainfall and the effect of separating the solid and liquid fractions of manure and only applying the liquid fraction. The results showed that flux densities immediately after field application were correlated with total N in the applied manure regardless of the treatment effect, although slight differences did appear. In later days the treatment effects became more apparent. Rainfall events of approximately 1 mm h^-1 suppressed NH₃ fluxes on subsequent days after spreading. NH₃ losses immediately after field application appeared to be slightly enhanced by watering, although the effects of the total N applied were dominant. Applying the liquid fraction of separated manure resulted in slightly higher initial fluxes. Losses were subsequently reduced as the liquid manure leached into the soil.