Agriculture Reference
In-Depth Information
Fig. 2.5.1.
A typical SOM transformation model. Pool decomposition rates are determined by
intrinsic rate constants K
i
and extrinsic rate modifiers F; partition functions
Φ
ij
are shown where
required by the reaction network.
through time as their reactivity declines according to a pre-defined pattern.
This model, however, becomes mathematically equivalent to the others
wherever a sufficient range of (usually geometrically distributed) pool
reactivities (
K
i
) is considered. It is conceptually distinct but, given enough
pools,
functionally
equivalent
to
the
majority.
It
too
assumes
areal
homogeneity and effective first-order kinetics.
Transformation processes within these models are typically represented
by some form of Equation 1:
V
i
=
K
i
F
i
(
T
,
Θ
,
C
)
Y
i
(1)
with partitioning between products being handled by some form of
equation [2]:
j
≠
∑
1
J
ij
=
Φ
ij
(
T
,
Θ
,
C
);
Φ
ij
(
T
,
Θ
,
C
)=1
(2)
In these equations,
V
i
is the decomposition rate of substrate Y
i
,
Y
i
is its
concentration and
K
i
its effective first-order decomposition rate constant;
F
i
(
T
,
,
C
) is a modifier function representing the effects on Y
i
decomposi-
tion of temperature (
T
), volumetric moisture content (
Θ
Θ
) and clay fraction
(
C
);
J
ij
is the flux from source pool
i
to target pool
j
, and
Φ
ij
(
T
,
Θ
,
C
)isthe
corresponding partition function. Upper case symbols (
T
,
Θ
,
C
,
Y
i
,
F
i
,
V
i
,
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