Application of Dairy Effluents to Pastures Affects Soil Nitrogen Dynamics and Microbial Activity

Abstract

The use of farm dairy effluents (FDE) has become a promising alternative to increase pasture yield while reducing the environmental impact of waste accumulation into streams, but other environmental implications should be considered. The present study aimed to assess the effect of application of either raw FDE or lagoon-stored FDE compared to dissolved urea or a non-amended control on N2O emission, soil N dynamics, functional microbial activity, and the yield and N-use efficiency of a fescue pasture. The normalized N application rate of 200 kg N ha−1 was divided into four seasonal events in a greenhouse experiment. Similar fescue forage production with FDE or urea positioned FDE application to soil as an alternative disposal. The repeated application of raw effluent delivered more organic C to the soil which induced an increase in enzyme activities, a shift in the catabolic activity of the soil microbial community, and greater N mineralization potential. On the other hand, urea addition decreased the functional activity of the soil microbial community. However, N2O emissions were greater for the raw effluent, so lagoon-stored effluent is an alternative to manage FDE under these conditions, avoiding urea addition and enhancing soil metabolic activity.

Differences in Bacterial Communities and Pathogen Indicators of Raw and Lagoon-Stabilized Farm Dairy Effluents

“…Therefore, considering that low temperatures decrease the activity of various microorganisms and slow the rate of organic matter degradation, it was expected that the TOC in DE would be higher in winter sampling and, accordingly, higher TN and lower cation content concentrations were found in the Lagoon samples ( Table 1 and Table S1 ). Previous studies showed similar results [ 38 , 50 ]. Thauera species were as identified as major denitrifying bacteria that occurred in digested DE [ 51 ], and their increase revealed in the Lagoon samples during the warmest sampling may suggest a role in N removal, as postulated by Ren et al [ 34 ].…”

Potential of Vermifiltration Technique to Reduce Chemical Oxygen Demand, Biological Oxygen Demand, and Total Suspended Solid of Farm Dairy Effluent in Developing Countries: Case of Indonesian Farm Dairy Industry

“…When organic materials are added to the soil, the carbon is broken down by soil microorganisms and incorporated into the soil organic matter [3]. Studies have shown that the application of FDE to soil can increase the soil's mineralization potential and improve its microbial activity and functional diversity [4]. The mineralization of FDE in the soil can also contribute to the release of nitrogen and other nutrients that can be taken up by plants [5].…”