Comparison of Measurable and Conceptual Soil Organic Carbon Pools Using the RothC Model in Eurasia Steppe Soils Under Different Land Use

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The Rothamsted Carbon model (RothC model) and Chikugo model were applied to 39 soils and corresponding climate data in Ukraine and Kazakhstan to compare (i) carbon input estimated using the RothC model and net primary productivity (NPP) estimated using the Chikugo model, (ii) estimated resistant plant material carbon pool (RPM) using the RothC model and measured light fraction carbon (LFC) content, and (iii) potentially mineralizable carbon (PMC), estimated using the RothC model, as well as measured PMC. Both RPM and PMC estimated using the RothC model correlated well with measured LFC and measured PMC, especially for natural vegetation sites (grassland and forest). For cropland sites, LFC and PMC did not account for the estimated RPM and PMC. These results suggest the utility of LFC and PMC as indices for monitoring carbon dynamics in natural ecosystems. Further studies are required to understand the source of readily mineralizable carbon in agro-ecosystems.