Greenhouse gas balance of an establishing Sphagnum culture on a former bog grassland in Germany.

The cultivation of Sphagnum mosses on re-wetted peat bogs for use in horticulture is a new land use strategy. We provide the first greenhouse gas balances for a field-scale Sphagnum farming experiment on former bog grassland, in its establishment phase. Over two years we used closed chambers to make measurements of GHG exchange on production strips of Sphagnum palustre L. and Sphagnum papillosum Lindb. and on irrigation ditches. Methane fluxes of both Sphagnum species showed a significant decrease over the study period. This trend was stronger for S. papillosum. In contrast, the estimated CO₂ fluxes did not show a significant temporal trend over the study period. The production strips of both Sphagnum species were net GHG sinks of 5- 9 t haC^-1 aC^-1 (in CO₂-equivalents) during the establishment phase of the moss carpets. In comparison, the ditches were a CO₂ source instead of a CO₂ sink and emitted larger amounts of CH₄, resulting in net GHG release of ~11 t haC^-1 aC^-1 CO₂-equivalents. We conclude that Sphagnum farming fields should be designed to minimise the area covered by irrigation ditches. Overall, Sphagnum farming on bogs has lower on-field GHG emissions than low-intensity agriculture. [ABSTRACT FROM AUTHOR]