WATER-MANURE INTERACTIONS ON AMMONIA VOLATILIZATION

The integrated horizontal flux method was used to determine NH3 volati lization from surface-applied swine manure (Sus scrofa domesticus). Th is method allows simple NH3 flux estimates to be made from small sourc e 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 immediate ly after field application were correlated with total N in the applied manure regardless of the treatment effect, although slight difference s 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 a pplication appeared to be slightly enhanced by watering, although the effects of the total N applied were dominant. Applying the liquid frac tion of separated manure resulted in slightly higher initial fluxes. L osses were subsequently reduced as the liquid manure leached into the soil.