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| Titel |
Regional variability of environmental effects of energy crop rotations |
| VerfasserIn |
Anne-Katrin Prescher, Christiane Peter, Xenia Specka, Matthias Willms, Michael Glemnitz |
| Konferenz |
EGU General Assembly 2014
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 16 (2014) |
| Datensatznummer |
250098395
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| Publikation (Nr.) |
 EGU/EGU2014-14069.pdf |
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| Zusammenfassung |
| The use of energy crops for bioenergy production is increasingly promoted by different
frameworks and policies (ECCP, UNFCCC). Energy cropping decreases greenhouse gas
emissions by replacing the use of fossil fuel. However, despite this, growing in
monocultures energy crop rotations has low environmental benefit. It is broadly accepted
consensus that sustainable energy cropping is only realizable by crop rotations
which include several energy crop species. Four crop rotations consisting of species
mixtures of C3, C4 and leguminous plants and their crop positions were tested to
identify the environmental effect of energy cropping systems. The experimental
design included four replicates per crop rotation each covering four cultivation
years. The study took place at five sites across Germany covering a considerable
range of soil types (loamy sand to silt loam), temperatures (7.5 °C – 10.0 °C) and
precipitation (559 mm – 807 mm) which allow a regional comparison of crop rotation
performance. Four indicators were used to characterize the environmental conditions: (1)
greenhouse gas (GHG) emissions from the management actions; (2) change in humus
carbon (Chum); (3) groundwater recharge (RGW) and (4) nitrogen dynamics. The
indicators were derived by balance, by an empirical model and by a dynamic model,
respectively, all based and calibrated on measured values. The results show that the crop
rotation impact on environmental indicators varied between plant species mixtures and
the crop positions, between sites and climate. Crop rotations with 100 % energy
crops (including C4 plants) had negative influence on Chum, GHG emissions per
area and RGW in comparison to the rotation of 50 % energy crops and 50 % cash
crops, which were mainly due to the remaining straw on the field. However, the
biogas yield of the latter rotation was smaller, thus GHG emissions per product were
higher, pointing out the importance to distinguish between GHG emissions per
product and per area. The perennial legume rotation was identified as the most
beneficial and eco-friendly energy crop rotation by showing an increase in Chum, lower
GHG emissions per product and area and positive effects on nitrogen dynamics.
However, the absolute magnitude of changes and effects differs between the sites
indicating an influence of soil type and local climate on the final performance of
the energy crop rotation. Generally, the results showed that the positive effect of a
certain crop rotation on particular environmental indicators can have a less beneficial
effect on another indicator, making an overall evaluation of the energy crop rotation
complicated. The weighing of different environmental indicators finally depends on
the environmental priorities, political targets and describes a further challenge. |
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