Emission of NH3 and N2O after spreading of pig slurry by broadcasting or band spreading

The recommended method of reducing the emission of NH3 while spreading manu re is to plough or harrow the manure into the soil. This in turn increases the possibility of N2O emission. At two sites in southern Sweden emissions of NH3 and N2O were measured after spreading pig slurry by broadcasting and band spreading. The band spreading technique can be used in growing crops i.e. when nitrogen is most needed, and it is thought that the NH3 emission is smaller with this technique compared to broadcasting. The average NH3 lo ss was 50% of applied NH4+ during warm/dry conditions and 10% during cold/w et conditions. The N2O emission was always less than 1% of applied NH4+. Wh en the NH3 emission decreased, the direct N2O emission increased. However, when taking into account the indirect N2O emission due to deposition of NH3 outside the field, the spreading techniques all produced similar total N2O emissions. The ammonia emission was not much lower for the band spreading technique compared to broadcasting, when compared on seven occasions.