TY  - JOUR
AU  - Weihermüller, L.
AU  - Huisman, J. A.
AU  - Graf, A.
AU  - Herbst, M.
AU  - Séquaris, J.-M.
TI  - Multistep Outflow Experiments to Determine Soil Physical and Carbon Dioxide Production Parameters
JO  - Vadose zone journal
VL  - 8
SN  - 1539-1663
CY  - Madison, Wis.
PB  - SSSA
M1  - PreJuSER-5537
SP  - 772 - 782
PY  - 2009
N1  - We want to thank H. Hardelauf for the implementation of all necessary features into the SOILCO2-RothC code. We also want to thank C. Walraf for the C-pool fractionation and T. Schuster for his helpful hands during the experimental setup. This research was supported by the German Research Foundation DFG (Transregional Collaborative Research Centre 32-Patterns in Soil-Vegetation-Atmosphere Systems: Monitoring, Modelling, and Data Assimilation).
AB  - Soil water content (SWC) plays a crucial role in the production and transport of CO2 in soils. Classical approaches estimating the effects of SWC on soil respiration are incubation experiments, where soil structure is disturbed and processes are neglected. Nevertheless, such data govern the water reduction function of C turnover models. our approach, the water reduction control parameters (WRCP) of a water reduction function were estimated from experiments using inverse modeling. Therefore, we used the SOILCO2-RothC model in combination with multistep outflow (MSO) experiments. First, the effective hydraulic properties were estimated and then used in a second to estimate the WRCP and rate constants of the resistant plant material (RPM) C pool. The results showed the estimated hydraulic parameters can be used for the prediction of CO2 production and transport of a second experiment only if the WRCP and the C turnover rate of the RPM pool of RothC will also be optimized. Optimizing the WRCP matched the CO2 efflux fairly well but the WRCP at the highest matric potential, which determines the of reduction, was too low at -1.61 cm and (water-filled pore space [WFPS] = 99.9%). Calibrating both WRCP and the rate constant matched the efflux again fairly well and the results indicate a reduction of optimal CO2 production water contents of 0.224 m(3) m(-3) or 53.3% WFPS. Also, the estimated RPM rate constant seems to be in a reasonable at k(RPM) = 2.5791 x 10(-7) cm(-1).
KW  - J (WoSType)
LB  - PUB:(DE-HGF)16
UR  - <Go to ISI:>//WOS:000268871900024
DO  - DOI:10.2136/vzj2008.0041
UR  - https://juser.fz-juelich.de/record/5537
ER  -