Effect of novel covering digested dairy slurry store on ammonia and methane emissions during subsequent storage

The objectives of this study were to evaluate the effects of the novel cover, a ‘hydrophobic powder’ containing plant-nutritional components, on ammonia, methane, and other gas emissions during subsequent storage of the digested dairy slurry and following nutritional constituents in the slurry. The novel cover was prepared by mixing finely ground ammonium phosphate and ammonium sulfate with hydrophobic silica, which made the novel cover possible to be floated on the slurry. Laboratory trials were carried out for 13 days using a pilot scale device. Four liters of dairy digested or raw slurry was placed in a glass beaker and the hydrophobic particle was floated on the slurry, where the particle layer would attain to 10% of height of the slurry. Cumulative volumes of ammonia and methane gases emitted from the digested slurry were considerably higher than those of the raw slurry. The novel cover could reduce the ammonia and methane emissions remarkably by reducing the emitting surface and/or by adsorbing these gases. The partial dissolution of the hydrophobic fine particle resulted in the increase in the nutritional efficiency of the dairy slurry, which could be useful for the bio-recycling of manures.