Mechanistic simulation of vertical distribution of carbon concentrations and residence times in soils

• Published in: Soil Science Society of America journal Vol. 59; no. 5
• Main Authors: Elzein, A. (INRA, Versailles, France.), Balesdent, J
• Format: Journal Article
• Language: English
• Published: 01.09.1995
• Subjects: CARBONE; CARBONO; CICLO BIOGEOQUIMICO; CONVECCION; CONVECTION; CYCLE BIOGEOCHIMIQUE; DEGRADACION; DEGRADATION; DIFFUSION; DIFUSION; MATERIA ORGANICA; MATIERE ORGANIQUE; MODELE DE SIMULATION; MODELE MATHEMATIQUE; MODELOS DE SIMULACION; MODELOS MATEMATICOS; PROCESOS DE TRANSPORTE EN EL SUELO; SOL; SOL DE FORET; SOL TROPICAL; SUELO; SUELO FORESTAL; SUELO TROPICAL; TEXTURA DEL SUELO; TEXTURE DU SOL; TIPOS CLIMATICOS DE SUELOS; TRANSPORT DANS LE SOL; TYPE DE SOL CLIMATIQUE
• ISSN: 0361-5995; 1435-0661
• DOI: 10.2136/sssaj1995.03615995005900050019x

We developed a numerical simulation model of the decay and vertical transport of soil organic matter. Soil organic matter is divided into a number of compartments each with different decay rates but with similar migration parameters. Decay has been represented with first-order processes. Two elementary forms of migration were explored: diffusive equations represent transport through soil mixing whereas translational convection simulates movement within the liquid phase. Coefficients of decay, diffusion, and convection were taken to be uniform with depth. Carbon input is both through the surface in the form of litter fall and directly underground from roots. Profiles of total C content and (14)C content were measured for a temperate forest silt loam soil. Similar data for other forest soils, available in the literature, were also assembled. Statistical adjustment, through nonlinear regression, of decay, migration, compartment configuration, and plant production parameters, accurately simulated profiles of C and (14)C. The rapidly decaying compartment was successfully likened to the 50- to 2000-micrometer particle-size fraction. Convection rates of approximately 0.3 mm yr(-1) and diffusion rates ranging from 1 to 15 cm(2) yr(-1) were obtained. Diffusive processes appear to be preponderant relative to convection. The model has proven sensitive to differences between temperate and tropical soils as well as textural variations