Lin Yu developed with the rest of the Jena Soil Model (JSM) team a novel soil model (Yu et al., 2020a) and they further tested what is the improvement of this new model in comparison to the original one-dimensional soil model of the QUINCY model. Improving the soil modelling is important, since the current models are not capturing all the relevant interactions between plants and soil.
The original QUINCY soil model had already some novel features as vertical resolution and fully coupled nitrogen (N) and phosphorus (P) cycles. The novelties of JSM are in having explicit presentation of the microbial processes (decomposition and stabilization with microbial adaptation concept) and using equilibrium chemistry approach (ECA) to simulate competition of substrate uptake kinetics. In the first paper the model is introduced and model experiments are performed to obtain understanding of the studied site and model. It is concluded that the C and N cycle are decoupled from the P cycle. The C and N cycles are influenced by the depolymerisation and organo-mineral association, whereas P cycle is very connected to microbial processes. The study calls for more detailed understanding of the microbial dynamics.
In the follow-up study (Yu et al., 2020b) the authors compared the first-order kinetics soil model version of QUINCY with JSM at five different German beech sites with varying P stocks. At the sites also fertilization experiments have been conducted (both N and P) and these were also simulated. The JSM outperformed the simple soil model in QUINCY, when comparing against the measured soil profiles. The authors also make comparisons of the heterotrophic respiration response to nutrient additions, but here there isn’t data to help in evaluation, instead there are theoretical considerations for the diverging responses between the model. As in the earlier paper, the authors state the importance of the microbial processes as well as of the organo-mineral association processes. This is very fascinating work, and I wait forward for the results from the work where also plants are interacting with JSM (I know this is ongoing…).
References
Yu, L., Ahrens, B., Wutzler, T., Schrumpf, M., and Zaehle, S., 2020a: Jena Soil Model (JSM v1.0; revision 1934): a microbial soil organic carbon model integrated with nitrogen and phosphorus processes, Geosci. Model Dev., 13, 783–803, https://doi.org/10.5194/gmd-13-783-2020, 2020.
Yu, L., Ahrens, B., Wutzler, T., Zaehle, S., and Schrumpf, M., 2020b : Modeling Soil Responses to Nitrogen and Phosphorus Fertilization Along a Soil Phosphorus Stock Gradient. Front. For. Glob. Change, 15 October 2020, https://doi.org/10.3389/ffgc.2020.543112.