Determination of microbial versus root‐produced CO2 in an
agricultural ecosystem by means of δ13CO2 measurements
in soil air |
| |
| Authors: | WOLFRAM SCHÜßLER ROLF NEUBERT INGEBORG LEVIN NATALIE FISCHER CHRISTIAN SONNTAG |
| |
| Institution: | Institut für Umweltphysik, Universität Heidelberg, Im Neuenheimer Feld 229, D‐69120 Heidelberg, Germany;Centrum voor Isotopenonderzoek, Rijksuniversiteit Groningen, Nijenborgh 4, NL‐9747 AG Groningen, The Netherlands |
| |
| Abstract: | The amounts of microbial and root‐respired CO2 in a maize/winter wheat agricultural system in south western Germany were investigated by measurements of the CO2 mixing ratio and the 13C/12C ratio in soil air. CO2 fluxes at the soil surface for the period of investigation (1993–1995) were also determined. Root respired CO2 shows a strong correlation with the plant mass above ground surface of the respective vegetation (R2≥0.88); the maximum CO2 release from roots was in August for the maize (2.0±0.5 mmol m?2 h?1) and in June for winter wheat (1.5±0.5 mmol m?2 h?1). Maximum CO2 production by roots correlate well with the maximum amount of plant root matter. Integrating the CO2 production over the whole growing season and normalizing to the dry root matter yields, the CO2 production per gram dry organic root matter (DORM) of maize was found to be 0.14±0.03 gC (g DORM)?1. At the sites investigated, root‐produced CO2 contributed (16±4)% for maize, and (24±4)% for winter wheat, respectively, to the total annual CO2 production in the soil (450±50 gC m?2 for maize, 210±30 gC m?2 for winter wheat). |
| |
| Keywords: | |
|
|
