Becker-Heidmann, P., Scharpenseel, H.-W. (1988): Natural 14C and 13C distribution pattern and organic matter dynamics in alfisols. XIXth ESNA-Conference, 29.08.-02.09.1988, Wien, Österreich. Abstracts Book, S. 46
With the thin layer sampling method and by measuring the natural abundances of 14C and 13C a variety of soils were investigated regarding the dynamics of the organic matter. The influence of soil order, climate and management practices on the depth distributions of the isotopes were studied. The soils comprise Alfisols , Vertisols, Ultisols, Mollisols and Inceptisols. The climates range from semiarid tropics to humid to mediterranean climate.
While in the agricultural soils plowing leads to a uniform isotope concentration in the topsoil, in the forest soils δ13C rises with depth, due to decomposition and translocation of decomposition metabolites. Constant δ13C values in clay enriched horizons reveal fixation of the organic matter with the clay. Descending δ13C values with depth within the topsoil correlate with a change of cultivation from pulses to sorghum. A high biological activity and turnover of organic matter is shown by high 14C abundances. In the argillic horizons the 14C activity decreases with depth, which is the same as increasing radiocarbon age, in correspondence to the δ13C results of clay fixation. Peak values of the 14C activity reveal changes in soil texture and percolation dynamics of dissolved organic matter.