Abbau der Rückstände von Lolium perenne und dadurch initiierte Priming-Effekte in Böden unterschiedlicher Nutzung

The decomposition of shoot and root residues of Lolium perenne was tested in two grassland and two arable soils from the Kraichgau area (Baden-Wurttemberg, Germany) by incubation for three months under optimal conditions (20 °C, 60 % of mWK) in laboratory. The dynamics of 14 CO 2 and total CO 2 efflux during the incubation and soil N min before and after incubation were measured. Two periods with different rates of decomposition of shoots and roots of Lolium were found. The slowly decomposable portion amounted to 86 %. The decomposition rates of the easily decomposable portion of shoots amounted to 0.2 day -1 . The decomposition rates of shoots are three times faster that the decomposition rates of roots. The decomposition rates were independent from the soil management. Input of roots into grassland soil leads to intensive carbon immobilisation in soil. Input of shoots into soils induced the extra decomposition of soil organic matter at the beginning. This can be interpreted as a positive priming effect. Carbon accumulation was observed in all variants of the experiment after two weeks. The decomposition of shoots leads to the additional nitrogen mineralisation from soil organic matter-positive N priming effect of 15 to 53 kg N ha -1 during three months. The decomposition of roots leads to N immobilisation of 0 to 42 kg N ha -1 .