Nitrogen transformation and nitrous oxide emissions from various types of farm effluents

With land disposal of the farm effluents as an accepted practice, concerns are viewed for its effect on the nitrous oxide (N2O) emissions. This study was undertaken to determine the effect land application of different farm effluents (treated farm dairy effluent (TFDE), untreated farm dairy effluent (UFDE), treated piggery farm effluent (TPFE) and treated meat effluent (TME)) have on N2O emissions from soil. N2O emissions were measured in the field using closed chamber technique. Effluents were added to the plots at a constant hydraulic loading of 25 mm with total volume of effluent applied for each plot being 50 l. Some soil properties like Soil bulk density, water filled pore space, oxygen diffusion rate (ODR), mineral nitrogen and dissolved organic carbon were measured along with the N2O flux measurement to assess their correlation with variation observed in N2O flux. The emissions rate was affected by the type of the effluent with TPFE emitting the highest (0.585 kg N2O–N ha−1 or 2.17% of the total added effluent-N) during autumn application and TME emitting the highest (0.286 kg N ha−1 0.84% of the total effluent-N added) during winter application. The difference in the N2O emissions among the effluents could be attributed to the difference in their C:N ratio. The return to pre-application N2O emissions rates within 2 weeks of autumn effluent application and 3 weeks of winter effluent application indicates that the effect of effluent application on flux is short lived. Correlation studies indicate that N2O flux was affected by some of the above mentioned soil properties.