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Dynamics of soil organic matter turnover and soil respired CO 2 in a temperate grassland labelled with 13 C
Author(s) -
Theis D. E.,
Jaeggi M.,
Aeschlimann D.,
Blum H.,
Frossard E.,
Siegwolf R. T. W.
Publication year - 2007
Publication title -
european journal of soil science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.244
H-Index - 111
eISSN - 1365-2389
pISSN - 1351-0754
DOI - 10.1111/j.1365-2389.2007.00941.x
Subject(s) - soil water , fumigation , soil respiration , organic matter , chemistry , grassland , respiration , temperate climate , soil organic matter , environmental chemistry , rhizosphere , ecosystem , agronomy , environmental science , carbon dioxide , soil science , botany , ecology , biology , genetics , organic chemistry , bacteria
Summary The fate of carbon (C) in grassland soils is of particular interest since the vast majority in grassland ecosystems is stored below ground and respiratory C‐release from soils is a major component of the global C balance. The use of 13 C‐depleted CO 2 in a 10‐year free‐air carbon dioxide enrichment (FACE) experiment, gave a unique opportunity to study the turnover of the C sequestered during this experiment. Soil organic matter (SOM), soil air and plant material were analysed for δ 13 C and C contents in the last year of the FACE experiment (2002) and in the two following growing seasons. After 10 years of exposure to CO 2 enrichment at 600 ppmv, no significant differences in SOM C content could be detected between fumigated and non‐fumigated plots. A 13 C depletion of 3.4‰ was found in SOM (0–12 cm) of the fumigated soils in comparison with the control soils and a rapid decrease of this difference was observed after the end of fumigation. Within 2 years, 49% of the C in this SOM (0–12 cm) was exchanged with fresh C, with the limitation that this exchange cannot be further dissected into respiratory decay of old C and freshly sequestered new C. By analysing the mechanistic effects of a drought on the plant‐soil system it was shown that rhizosphere respiration is the dominant factor in soil respiration. Consideration of ecophysiological factors that drive plant activity is therefore important when soil respiration is to be investigated or modelled.