ISSN:
1573-5036
Keywords:
13C isotope
;
changes in soil
;
forest clearing
;
maize crop
;
modelling
;
soil organic carbon
Source:
Springer Online Journal Archives 1860-2000
Topics:
Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
Notes:
Abstract In southwest France, thick humic acid loamy soils have developed from Quaternary silty alluvial deposits. On these soils, most forest lands have been converted to continuous intensive maize cropping and the loss of C upon conversion to intensive agriculture has been shown to be significant. The objective of this study was to determine if a study of natural 13C abundance in soil organic C makes possible an improved modelling of organic carbon turnover in the cultivated horizons of soils in this landscape in southwest France. A chronosequence study is realized by comparing C pools and C-13 natural abundance of three forest sites and 14 adjacent agricultural sites, whose ages of cultivation ranged from 3 to 32 yr. δ13C ratio is found to increase with time of cultivation. The fraction of C coming from the maize crop increases during the first decades of cultivation, and reaches a plateau thereafter. This equilibrium level is reached after a few decades of cultivation. The decrease of the initial C pool is fitted by a simple model assuming that about half of this pool is mineralized during the first yr of cultivation whereas the other half decreases at a slower rate. Therefore, a general bi-compartmental model is proposed for describing the soil organic carbon dynamics in these soils after forest clearing and intensive maize cropping.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00011455
