MODELLING CARBON FLOWS IN CROP AND SOIL. Krisztina R. Végh. Carbon and Nitrogen flows and storage. Eckersten, 1994). Carbon flows in the CoupModel. Organic residues: surface litter, rhizodeposition: 900-3000 kg C/ha. C/N:20-80. C/N:10-30. Dissolved organics. (Jansson, 2004).
MODELLING CARBON FLOWS IN CROP AND SOIL
Krisztina R. Végh
Carbon and Nitrogen flows and storage
Carbon flows in the CoupModel
Organic residues: surface litter,
rhizodeposition: 900-3000 kg C/ha
C input: crop growth
3 approaches for the simulation of plant growth :
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.
Allocation of assimilated C to the different plant parts
Plant biomass is divided into compartments of carbon (CLeaf, CStem, CRoot, Cgrain Cmobile)
Different response functions of C allocation to roots from above ground mass
shoot mass, water stress, leaf C:N
Decomposition and mineralization – Soil organismsm are implicit
The decomposition is substrate controlled and calculated as a first order rate process:
When soil organisms are implicit, the soil profile includes maximum of three carbon pools with specific decomposition rates kl, kf, kh.
The relative amounts of decomposition products
The three rate constants are affected by response functions for soil moisture (f) and temperature (fT).
Efficiency parameter fe determines the fraction of Cthat is not released from the soil as CO2
Organic carbon pools and carbon flows in the soil
Estimated consumption rate of microbes with their efficiency explicitly taken into account + respiration of microbial biomass
fraction of microbes located in the different pools
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.