Horizon 1 1 17 ACL : Articles dans des revues avec comité de lecture répertoriées par l'AERES Biology and Fertility of Soils 797-804 C dynamics decomposition plant residue quality N availability 2007 fdi:010040723 ENG Biology and Fertility of Soils 0178-2762 CC:0002479995-0019 6 10.1007/s00374-007-0169-y https://www.documentation.ird.fr/hor/fdi:010040723 https://www.documentation.ird.fr/intranet/publi/2007/10/010040723.pdf 43 Horizon (IRD) This study assessed the respective roles of biochemical quality and N content of plant residues on C and N dynamics in a soil. Both N-15- and C-13-labeled oilseed rape residues (roots, seedpod walls) combining different biochemical characteristics and similar N content or the same biochemical characteristics and different N contents were used as amendments. These treatments were combined with two levels of soil inorganic N to ensure that decomposition was not limited by N availability. The soil was incubated under laboratory conditions for 134 days. Soil amended with residues of similar biochemical quality (i.e. the two pod walls) displayed similar C mineralization dynamics when the initial N availability (residue+soil N) ranged from 1.7 to 3.2% of residue dry matter. The roots showed poorer decomposition than the pod walls, lower cumulative C mineralization and greater accumulation of root-derived C in the > 50 mu m coarse fraction of the soil organic matter. The N content of the residues influenced mineral N accumulation in the soil with a lower net immobilization of residues with low C-to-N ratios. Adding an exogenous source of inorganic N had no effect on C dynamics but modified the remineralization kinetics of the previously immobilized N, suggesting changes in the microbial community involved. 068