Δημοσιεύσεις σε Περιοδικά

Μόνιμο URI για αυτήν τη συλλογήhttps://dspace.library.tuc.gr/handle/123456789/135

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A coupled carbon, aggregation, and structure turnover (CAST) model for topsoils
(Elsevier, 2013) Stamati Foteini; Σταματη Φωτεινη; Nikolaidis Nikolaos; Νικολαιδης Νικολαος; Banwart, Steven A; Blum Winfried
The current multi-pool soil organic carbon (SOC) models, although a major improvement over the single pool ones, are not always able to capture soil saturation capacity and give reliable predictions for climate change effects, since they do not account for environmental constraints, like physical protection. In this work, we developed a soil carbon, aggregation, and structure (CAST) turnover model based on the concept suggested by many authors in the scientific literature that macroaggregates are formed around particulate organic matter, followed by the release of micro-aggregates. A simplified mechanistic Nitrogen model was also developed. The CAST model was evaluated by field data of cropland to set aside conversions of Critical Zones Observatories in Greece (fine textured Mediterranean) and Iowa (coarse textured humid continental). The model was able to capture the carbon content and the C-to-N ratio content of the pools comprising the three aggregate types (macroaggregates: >250 μm, micro-aggregates: 53-250 μm, silt-clay sized aggregates: <53 μm) in both sites. The soil system reached maximum macro-aggregation/porosity and minimum bulk density after 7 and 14 years in Greece and Iowa, respectively. Afterwards, macro-aggregate disruption presented a constant seasonal pattern and any further SOC increase was due to micro-aggregation resulting in the increase of bulk density and decrease of porosity towards to a stable value. The CAST model can assist in revealing primary factors determine organic matter, aggregation, and structure turnover in different ecosystems and in describing the response of the soil system to management practices, land use changes, and climate change in order to design and optimize the appropriate measures/practices.
Modeling topsoil carbon sequestration in two contrasting crop production to set-aside conversions with RothC–Calibration issues and uncertainty analysis
(Elsevier, 2013) Nikolaidis Nikolaos; Νικολαιδης Νικολαος
Model simulations of soil organic carbon turnover in agricultural fields have inherent uncertainties due to input data, initial conditions, and model parameters. The RothC model was used in a Monte-Carlo based framework to assess the uniqueness of solution in carbon sequestration simulations. The model was applied to crop production to set aside conversions in Iowa (sandy clay-loam soil, humid-continental climate) and Greece (clay-loam soil, Mediterranean). The model was initialized and calibrated with particulate organic carbon data obtained by physical fractionation. The calibrated values for the Iowa grassland were 5.05 t C ha-1, 0.34 y-1, and 0.27 y-1 24 for plant litter input and decomposition rate constants for resistant plant material (RPM) and humus, respectively, while for the Greek shrubland these were 3.79 t C ha-1, 0.21 y-1, and 0.0041 y-126 , correspondingly. The sensitivity analysis revealed that for both sites, the total plant litter input and the RPM rate constant showed the highest sensitivity. The Iowa soil was projected to sequester 17.5 t C ha-1 and the Greek soil 54 tC ha- 28 1 29 over 100 years and the projected uncertainty was 65.6% and 70.8%, respectively. We propose this methodology to assess the factors affecting carbon sequestration in agricultural soils and quantify the uncertainties.

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Πλοήγηση Δημοσιεύσεις σε Περιοδικά ανά Θέμα "Calibration"