Influence of ley-arable systems on soil carbon stocks in Northern Europe and Eastern Canada

摘要

Grassland is one of the dominant forms of land use in Europe and is considered to have a considerable potential for sequestration of soil carbon. Forage-based crop rotations under Nordic conditions often include both ley and arable crops. These systems, having components of both grassland and cropland, are expected to have C stocks intermediate between those in permanent grasslands and croplands. The effect of ley-arable rotations versus continuous annual cropping systems on stocks of soil organic carbon was quantified by analysing data from long-term field experiments in Nordic countries. Unpublished data from four sites in Sweden are presented and results from 11 published studies are summarized. In the different studies, depending on the speciescomposition, management, experimental period and soil depth, on average 0.52 Mg ha~(-1) yr~(-1) (range 0.3 to 1.1; median 0.42 Mg ha~(-1) yr~(-1)) more carbon was retained in soils in ley-arable compared to exclusively annual cropping systems.