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Dissolved organics Carbon flows in the CoupModel (Jansson, 2004) Organic residues: surface litter, rhizodeposition: kg C/ha C/N:20-80C/N:10-30
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MODELLING CARBON MODELLING CARBON FLOWS IN CROP AND SOILFLOWS IN CROP AND SOIL
Krisztina R. VéghKrisztina R. Végh
Carbon and Nitrogen flows and storage
Eckersten, 1994)
Dissolved organics
Carbon flows in the CoupModel
(Jansson, 2004)
Organic residues: surface litter,
rhizodeposition: 900-3000 kg C/haC/N:20-80 C/N:10-30
Logistic growth:
Water use efficiency
Light use efficiency
(t))N/Ef(EcnC pl,pstptapaAtm
tawaAtm EC
plstptaleafaLaAtm )R/E)f(E)f(CNf(TεC
the potential growth is a function of time
growth is estimated from WUE and simulated transpiration
light use efficiency is used to estimate potential growth rate, limited by unfavorable temperature, water and N conditions.
3 approaches for the simulation of plant growth :
C input: crop growth
Plant biomass is divided into compartments of carbon (CLeaf, CStem, CRoot, Cgrain Cmobile)
Allocation of assimilated C to the different plant parts
Different response functions of C allocation to roots from above ground mass
Options: linear functionexponential independent
)/()/( tptawcwctpta EErrEEf 21
MrMcMc
McerrMf .)( 321
1Mcr1Mcr
Original parametersdoubled:
2Mcr3Mcr
1wcr2wcr
shoot mass, water stress,
leaf C:N
Decomposition and mineralization – Soil organismsm are implicit
When soil organisms are implicit, the soil profile includes maximum of three carbon pools with specific decomposition rates kl, kf, kh.The three rate constants are affected by response functions for soil moisture (f) and temperature (fT).
Efficiency parameter fe determines the fraction of C that is not released from the soil as CO2
The relative amounts of decomposition products
The decomposition is substrate controlled and calculated as a first order rate process:
litterdecomp Cf(T)fkC )(1
Organic carbon pools and carbon flows in the soil
fraction of microbes located in the different pools subpools
Estimated consumption rate of microbes with their efficiency explicitly taken into account + respiration of microbial biomass
Decomposition :Substrate dependence,
CN ratio
Decomposition :
Substrate dependence,
Carbon contentration
Scons: substrate half rate concentration
The affects of parameters TemQ10 and
TemQ10Bas affect the response function Q10 temp. response function with a threshold value
Simulation models help to understand the mechanistic relationships between SOC and soil – plant interactions
C flows and OC pools are similarly conceptualized in several models. Simple switches to obtional pools, the possibility of the use of different allocation functions and several abiotic response functions help to describe the processes that interact simultaneously to control C dynamics in crop and soil.
Conclusions