 |
| Titel |
Greenhouse gas fluxes during growth of different bioenergy crops |
| VerfasserIn |
K. Walter, A. Don, H. Flessa |
| Konferenz |
EGU General Assembly 2012
|
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 14 (2012) |
| Datensatznummer |
250063777
|
|
|
|
|
|
| Zusammenfassung |
| Bioenergy crops are expected to contribute to greenhouse gas mitigation by substituting fossil
fuels. However, during production, processing and transport of bioenergy crops greenhouse
gas emissions are generated that have to be taken into account when evaluating the role of
bioenergy for climate mitigation. Especially nitrous oxide (N2O) emissions during feedstock
production determine the greenhouse gas balance of bioenergy due to its strong
global warming potential. This fact has often been ignored due to insufficient data
and knowledge on greenhouse gas emission from cropland soils under bioenergy
production. Therefore, we started to investigate the greenhouse gas emissions of major
bioenergy crops maize, oil seed rape, grass (grass-clover, without N-fertilizer) and
short rotation coppice (SRC, poplar hybrid) at two sites in Central Germany (near
Göttingen and in Thuringia). The nitrous oxide and methane (CH4) fluxes from
these sites have been determined by weekly chamber measurements since May
2011.
The N2O emissions from all fields were low and without extreme peaks during the first
five months of measurement (222 to 687 g N2O-N ha-1 for 5 months). The rape
field near Göttingen emitted less N2O than the SRC, probably because SRC was
newly established in spring 2011 and the rape has not been fertilized during the
measurement period (cumulative emission over 5 months: rape seed 366 ± 188 g N2O-N
ha-1, grassland 497 ± 153 g N2O-N ha-1, SRC 687 ± 124 g N2O-N ha-1). The
maize field in Thuringia emitted more N2O than the SRC due to emission peaks
related to the fertilization of maize (cumulative emission over 5 months: maize 492
± 140 g N2O-N ha-1, grasslands 253 ± 87 and 361 ± 135 g N2O-N ha-1, new
SRC 222 ± 90 g N2O-N ha-1, 4 years old SRC 340 ± 264 g N2O-N ha-1). All
sites showed a net uptake of atmospheric methane throughout the summer season
(104 to 862 g CH4-C ha-1 for 5 months). However, net-exchange of CH4 is of
little importance for the greenhouse gas budget of the anlysed crops. Emissions
related to management activities and during fertilizer production have to be taken
into account. Total emissions were related to the net energy yield of the different
crops.
Our first results indicate that perennial crops have the potential to reduce greenhouse gas
emissions from bioenergy crop production as compared to annual crops due to its lower
fertilizer demand. |
|
|
|
|
|
|