
TY  - JOUR
A1  - Bird, M. 
A1  - Kracht, O. 
A1  - Derrien, D. 
A1  - Zhou, Y. 
T1  - The effect of soil texture and roots on the stable carbon isotope composition of soil organic carbon
JF  - Soil Research
JO  - Soil Res.
Y1  - 2003
VL  - 41
IS  - 1
SP  - 77
EP  - 94
KW  - stable carbon isotopes, C13, carbon cycle.
UR  - https://doi.org/10.1071/SR02044 
N2  - This study examines the distribution of soil organic carbon and carbon-isotopes with depth and among particle size fractions in 2 forest soil profiles of contrasting texture from Cape York Peninsula, Queensland, Australia. The profile on sand has a comparatively low inventory of carbon (557 mg/cm2 from 0&#8211;100 cm) and exhibits comparatively small variations in &#948;13C value. In contrast, the clay-rich profile has a much larger inventory of soil organic carbon (1725 mg/cm2 from 0&#8211;100 cm) and large variations in &#948;13C value occur both with depth in the profile and between different particle size fractions. The considerable differences in carbon inventories and &#948;13C values between the sites appear to be largely due to soil textural differences. In the absence of fine minerals the trend in &#948;13C value with decreasing particle size is to similar or lower &#948;13C values, due to an increase in the relative abundance of low &#948;13C compounds in the residue left by microbial decomposition. In the presence of fine minerals, the trend is to higher &#948;13C values due to the stabilisation of the products of microbial decomposition by the fine minerals. Thus, the bulk &#948;13C value of soil organic carbon appears to be determined as much by the abundance of fine minerals in a soil profile as by isotope fractionation effects accompanying degradation. It is further postulated that an initial rapid rise in &#948;13C value in the upper soil layers is due to an increase in the relative importance of higher 13C, root-derived carbon immediately below the soil surface. 
ER  -

