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| Titel |
Theoretical and numerical analysis of a soil organic matter decomposition model along vertical soil profiles and coupling the dynamics of carbon and nutrients dynamics. |
| VerfasserIn |
Julien Sainte-Marie, Matthieu Barrandon, Laurent Saint-André, Antoine Henrot |
| Konferenz |
EGU General Assembly 2014
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 16 (2014) |
| Datensatznummer |
250097923
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| Publikation (Nr.) |
 EGU/EGU2014-13550.pdf |
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| Zusammenfassung |
| Abstract More than 250 models dedicated to the decomposition of the soil organic matter
(SOM) were developed over the last thirty years. Among them, E. Bosatta & G. Ågren have
proposed several equations based on the theory of organic matter quality noted q to describe
heterogeneous SOM dynamics. These models are ruling the fate of carbon and nutrients
concentrations in the soil organic matter.
One of these models considers the decomposition of SOM along a vertical soil profile [1].
Carbon and nutrients distribution functions are noted Ïc(q,z,t) and ÏÏ(q,z,t) (g cm2 q-1)
respectively where Ï is a specific nutrient. The mass balance provides the following
equations:
-Ïc(q,z,t) u(q,z) -« +- ′ ′ ′ ′ -[ν(q,z)Ïc(q,z,t)]
-t = - fc e(q) Ïc(q,z,t)+ fc 0 D (q,q )u(q,z)Ïc(q ,z,t)dq- -z ,(1)
-Ï (q,z,t) u(q,z) -« + - - [ν(q,z)Ï (q,z,t)]
–Ï––- = - fc––ÏÏ(q,z,t)+ fÏ D(q,q′)u(q′,z)Ïc(q′,z,t)dq′ ––––Ï––(2.)
-t e(q) 0 -z
where fc and fÏ are decomposer carbon and nutrient Ï concentrations; u(q,z) (g gc-1 t-1) is
the decomposer growth rate per unit of substrate carbon; e(q) is the decomposer efficiency;
D(q,q′) (q-1) is the dispersion function of quality; ν(q,z) (cmy-1) is the velocity of the
particles of organic matter.
This model considers continuous distributions in time, space and quality and requires few
parameters describing soil physics and micro-biological activity. Despite these conceptual
advantages, this particular approach was poorly used because of the absence of mathematical
analysis. Therefore, Bosatta & Ågren have chosen to simplify the equations to obtain explicit
solutions sufficient to describe a steady state. Here we extend their work from mathematical
point of view.
The existence and the uniqueness of solutions were proved for the original
model. A numerical method was also implemented to simulate SOM dynamics. The
consequences of model simplification were numerically studied by comparing the complete
model versus the simplified one. It results that model simplification is in general
not relevant and may have strong drawbacks when studying the heterogeneity of
SOM.
Our work was then an essential step to design a modeling toolbox able to investigate soil
data already available, using few parameters for soil physics and microbiological
activity, and suitable to various ecosystems. This work is included in a broader
modelling framework aiming at building a predictive tool for growth & yield of forest
ecosystems.
Reference [1] E Bosatta and GI Agren. Theoretical analyses of carbon and nutrient
dynamics in soil profiles. Soil Biology and Biochemistry, 28(10-11):1523 - 1531, 1996. |
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