R version of RothC model including two biochar and two exogenous organic matter pools

Expanded version of function 'RothCModel' included in SoilR package by Sierra et al. (2012). RothC is a soil carbon model originally developed by Jenkinson et al. (1990). Compared to the original version, this model includes two additional biochar pools and two exogenous organic matter (EOM) pools. The code was applied in Keel et al. (2023) to quantify the soil carbon sequestration potential for biochar additions. The scenarios are described in the paper and the output is published on Zenodo (https://doi.org/10.5281/zenodo.6413955). The EOM pools were added based on Mondini et al. (2017) but this version of the code was not applied in a publication so far. Cross tests against Claudio Mondini's version in Excel were performed and showed a good agreement (unpublished). Please cite Keel et al. (2023) if you apply this code for your own research. 

Keel S.G., Bretscher D., Leifeld J., von Ow A., Wüst-Galley C. 2023. Soil carbon sequestration potential bounded by population growth, land availability, food production, and climate change. Carbon Management, http://dx.doi.org/10.1080/17583004.2023.2244456

References:

Jenkinson, D. S., S. P. S. Andrew, J. M. Lynch, M. J. Goss, and P. B. Tinker. 1990. The Turnover of Organic Carbon and Nitrogen in Soil. Philosophical Transactions: Biological Sciences 329:361-368.

Mondini, C., Cayuela, M. L., Sinicco, T., Fornasier, F., Galvez, A., and Sánchez-Monedero, M. A. 2017. Modification of the RothC model to simulate soil C mineralization of exogenous organic matter, Biogeosciences, 14, 3253–3274, https://doi.org/10.5194/bg-14-3253-2017.

Sierra, C.A., M. Mueller, S.E. Trumbore. 2012. Models of soil organic matter decomposition: the SoilR package version 1.0. Geoscientific Model Development 5, 1045-1060.