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

Abstract. The recommended method of reducing the emission of NH₃ while spreading manure 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 loss was 50% of applied NH₄⁺ during warm/dry conditions and 10% during cold/wet conditions. The N₂O emission was always less than 1% of applied NH₄⁺. When 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.