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| Titel |
Short-term effects of biogas digestate and cattle slurry application on greenhouse gas emissions affected by N availability from grasslands on drained fen peatlands and associated organic soils |
| VerfasserIn |
T. Eickenscheidt, A. Freibauer, J. Heinichen, J. Augustin, M. Drösler |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1726-4170
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| Digitales Dokument |
URL |
| Erschienen |
In: Biogeosciences ; 11, no. 22 ; Nr. 11, no. 22 (2014-11-17), S.6187-6207 |
| Datensatznummer |
250117675
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| Publikation (Nr.) |
 copernicus.org/bg-11-6187-2014.pdf |
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| Zusammenfassung |
| A change in German energy policy has resulted in a strong increase in
the number of biogas plants in Germany. As a consequence, huge amounts of
nutrient-rich residues, the by-products of the fermentative process, are
used as organic fertilizers. Drained peatlands are increasingly used to
satisfy the huge demand for fermentative substrates (e.g., energy crops,
grass silage) and the digestate is returned to the peatlands. However,
drained organic soils are considered as hot spots for nitrous oxide
(N2O) emissions and organic fertilization is additionally known to
increase N2O emissions from managed grasslands. Our study addressed the
questions (a) to what extent biogas digestate and cattle slurry application
increase N2O and methane (CH4) fluxes as well as the mineral
nitrogen use efficiency (NUEmin) and grass yield, and (b) how different
soil organic matter contents (SOMs) and nitrogen contents promote the
production of N2O. In addition NH3 volatilization was determined
at one application event to obtain first clues with respect to the effects
of soil and fertilizer types. The study was conducted at two sites within a
grassland parcel, which differed in their soil organic carbon (SOC) and N
contents. At each site (named Corg-medium and Corg-high) three
plots were established: one was fertilized five times with biogas digestate,
one with cattle slurry, and the third served as control plot. On each plot,
fluxes of N2O and CH4 were measured on three replicates over 2
years using the closed chamber method. For NH3 measurements we used the
calibrated dynamic chamber method. On an annual basis, the application of
biogas digestate significantly enhanced the N2O fluxes compared to the
application of cattle slurry and additionally increased the plant N-uptake
and NUEmin. Furthermore, N2O fluxes from the Corg-high
treatments significantly exceeded N2O fluxes from the Corg-medium treatments.
Annual cumulative emissions ranged from 0.91 ± 0.49 to 3.14 ± 0.91 kg N ha−1 yr−1. Significantly
different CH4 fluxes between the investigated treatments or the
different soil types were not observed. Cumulative annual CH4 exchange
rates varied between −0.21 ± 0.19 and
−1.06 ± 0.46 kg C ha−1 yr−1. Significantly higher NH3
losses, NUEmin and grass yields from treatments fertilized with biogas
digestate compared to those fertilized with cattle slurry were observed. The
total NH3 losses following the splash plate application were
18.17 kg N ha−1 for the digestate treatments and 3.48 kg N ha−1 for the
slurry treatments (36 and 15% of applied NH4+–N). The
observed linear increase of 16 days' cumulative N2O–N exchange or annual N2O emissions, with mean groundwater level and ammonium
application rate, reveals the importance of site-adapted N fertilization and
the avoidance of N surpluses in Corg-rich grasslands. |
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