Preliminary Results on the Use of Straw Cover and Effective Microorganisms for Mitigating GHG and Ammonia Emissions in Pig Slurry Storage Systems

Spain has been the largest pork producer in the EU in recent years, leading to significant pig slurry (PS) production that requires proper management to prevent environmental impacts. The objectives of this study were to quantify greenhouse gas (GHG) and ammonia emissions and to characterize the PS in storage pond systems. A straw cover pond (SP) and addition of effective microorganisms (EMs) in a biological pond (BP) were used to treat the slurries. During two periods (autumn and spring), PS was characterized and GHG (CO2, CH4, N2O) and NH3 emissions were measured with a dynamic chamber. After 5 weeks of storage, BP achieved a reduction of 96% for CO2, 98% for CH4 and 59% for NH3 compared to the control pond (CP) in spring, while SP presented a 74% reduction for CO2 in autumn, and 60% and 97% reductions for CH4 and NH3, respectively, in spring. Additionally, the PS samples showed a decreasing trend for EC, dry matter, COD, BOD5, total N, NH4+-N, Org.-N, NO3−-N, and PO43− during both seasons. This preliminary study shows promise in reducing GHG/NH3 emissions and improving PS properties, but further replication is recommended. Varying straw cover thickness, optimizing EM dose, and a pH reduction may enhance outcomes.