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Field Nitrogen Losses Induced by Application Timing of Digestate from Dairy Manure Biogas Production
Author(s) -
Schwager Emily A.,
VanderZaag Andrew C.,
WagnerRiddle Claudia,
Crolla Anna,
Kinsley Chris,
Gregorich Ed
Publication year - 2016
Publication title -
journal of environmental quality
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.888
H-Index - 171
eISSN - 1537-2537
pISSN - 0047-2425
DOI - 10.2134/jeq2016.04.0148
Subject(s) - digestate , manure , leaching (pedology) , environmental science , biogas , silage , zoology , nitrous oxide , straw , nitrogen , agronomy , anaerobic digestion , soil water , chemistry , waste management , methane , organic chemistry , engineering , soil science , biology
Anaerobic digestion of dairy manure has environmental benefits, but the impact of effluent (i.e., digestate [DG]) application on environmental nitrogen (N) losses from soils has not been well quantified. Our objective was to evaluate how field application of DG affected nitrous oxide (N 2 O) emissions and nitrate (NO 3 ) leaching compared with raw dairy manure (RM) in spring versus fall applications. We measured N losses year‐round for 2.5 yr in silage corn on tile‐drained clay soil in Alfred, Ontario, Canada. Treatments were: digestate applied in spring (DS) and fall (DF), raw dairy manure applied in spring (RS) and fall (RF), urea applied in spring, and a control. Overall, the source of N had no effect on annual N 2 O emissions (overall average DG and RM, 4.9 kg N 2 O–N ha −1 yr −1 ), but more NO 3 leached from DS than RS treatments (8.8 and 4.8 kg NO 3 –N ha −1 yr −1 on average, respectively). Estimated indirect N 2 O emissions from leached NO 3 –N were small (<0.2 kg N 2 O–N ha −1 yr −1 ). Timing of application did not affect annual N 2 O emissions but did shift emissions to the non‐growing season for fall applications (65% on average) and to the growing season for spring applications (60% on average). Overall environmental N losses (N 2 O–N + NO 3 –N) from DG were similar to RM when applied at the same time. For the conditions of our study, downstream emissions from anaerobic digestion (i.e., emissions induced by applied digestate) do not present an adverse trade‐off to the environmental benefits incurred during the biogas production phase. Core Ideas Biodigestion has environmental benefits, but N losses from soils are uncertain. Nitrous oxide emissions and NO 3 leaching were evaluated. Digested and raw manure had similar annual N losses. Application in spring had lower annual NO3 losses than fall application. Soil emissions were not a trade‐off to environmental benefits of biogas production.