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Sommer J.,University of Gottingen | Dippold M.A.,University of Gottingen | Flessa H.,Institute of Climate Smart Agriculture | Kuzyakov Y.,University of Gottingen
Journal of Plant Nutrition and Soil Science | Year: 2016

Forest management requires a profound understanding of how tree species affect C and N cycles in ecosystems. The large C and N stocks in forest soils complicate research on the effects of tree species on C and N pools. In-situ 13C and 15N labeling in undisturbed, natural forests enable not only tracing of C and N fluxes, but also reveal insight into the interactions at the plant-soil-atmosphere interface. In-situ dual 13C and 15N pulse labeling of 20 beeches (Fagus sylvatica L.) and 20 ashes (Fraxinus excelsior L.) allowed tracing the fate of assimilated C and N in trees and soils in an unmanaged forest system in the Hainich National Park (Germany). Leaf, stem, root, and soil samples as well as microbial biomass were analyzed to quantify the allocation of 13C and 15N for 60 d after labeling and along spatial gradients in the soil with increasing distance from the stem. For trees of similar heights (≈ 4 m), beech (20%) assimilated twice as much as ash (9%) of the applied 13CO2, but beech and ash incorporated similar 15N amounts (45%) into leaves. The photosynthates were transported belowground through the phloem more rapidly in beech than in ash. Ash preferentially accumulated 15N and 13C in the roots. In contrast, beech released more of this initially assimilated 13C (2.0% relative 13C allocation) and 15N (0.1% relative 15N allocation) via rhizodeposition into the soil than ash (0.2% relative 13C, 0.04% relative 15N allocation), which was also subsequently recovered in microbial biomass. These results on C and N partitioning contribute to an improved understanding of the effects of European beech and ash on the C and N cycles in deciduous broad-leaved forest. Differences in C and N allocation patterns between ash and beech are one mechanism of niche differentiation in forests containing both species. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Severin M.,University of Gottingen | Fuss R.,Institute of Climate Smart Agriculture | Well R.,Institute of Climate Smart Agriculture | Hahndel R.,EuroChem Agro GmbH | Van den Weghe H.,University of Gottingen
Archives of Agronomy and Soil Science | Year: 2015

Nitrogen-use efficiency in arable agriculture after organic fertilization can be improved by the incorporation of digestate into soil and through the use of nitrification inhibitors. To test the efficiency and the interaction of these measures, a laboratory microcosm study was conducted with undisturbed samples from two arable soils – a Gleysol and a Plaggic Anthrosol. Treatments were digestate application by injection to 15 or 20 cm depths or by trailing hose with subsequent incorporation. Half of the replicates of each application treatment were treated with the nitrification inhibitor 3,4-dimethyl pyrazole phosphate (DMPP). Emissions of the greenhouse gases (GHGs) CO2, N2O and CH4 were monitored during 51 days of incubation. Deeper injection (20 cm) did not lead to different GHG emissions compared with a shallow injection (15 cm). Application of DMPP decreased cumulative N2O emissions significantly by 17–70%. DMPP inhibited N2O fluxes and NO3- production, suggesting a positive effect of DMPP on the mitigation of direct GHG emission and nitrate leaching at least during several weeks after digestate fertilization. The effect of DMPP is independent of the application technique. © 2015 Taylor & Francis


Offermann F.,Institute of Farm Economics | Deblitz C.,Institute of Farm Economics | Golla B.,Institute for Strategies and Technology Assessment | Gomann H.,Institute of Rural Studies | And 11 more authors.
Landbauforschung Volkenrode | Year: 2014

This article presents selected results of the Thünen-Baseline as well as the assumptions upon which these results are based. The Thünen-Baseline is established using and combining several models of theThünen model network. It provides a reference scenario for the analysis of the impacts of alternative policies and developments. The projections are based on data and information available as of winter 2013/14. The baseline assumes a continuation of the current policy framework and the implementation of already decided policy changes. For the Thünen-Baseline 2013 to 2023, this implies the implementation of the EU-CAP reform decided in 2013 and its national implementation according to the decisions made at the German Ministers of Agriculture conference. Overall, the Thünen-Baseline 2013 to 2023 draws a picture of a competitive agricultural sector in Germany, which adapts well to the changes of the latest policy reform and seizes the opportunities for expanding production, especially in the dairy sector. On the other hand, the projections also highlight that - under the assumptions made and with unchanged policy conditions - the problems that may accompany intensive livestock production will not simply dissolve. In contrast, in view of the projected high profitability of intensive pig and poultry production the related challenges could increase.

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