Compilation of data on soil organic carbon stocks and N2O emissions from published long term fields trials

This dataset was produced within the Landmark project to assess the accuracy of the DEXI climate regulation model. This was done by simulating the response of the soil organic carbon stock or N2O emissions from agricultural soils in long-term experiments (LTEs) and comparing the model outcomes to reported changes. LTEs were chosen because they facilitate the assessment of a range of different management practices on the component parts of the climate regulation function over a decadal timescale. The geographical location of the LTEs was limited to Europe, since the model has been developed specifically to make simulations across Europe. For this purpose, the database constructed by Sandén et al. (2018) was used. This database contains publications on 251 European LTEs in which the effect of alternative management practices on soil quality were assessed. From these, 78 LTEs reported on changes in SOC stocks and 40 reported on changes in N2O emission or NO3- leaching. A large portion of these LTEs studied the effect of tillage (n = 18 for N2O, n = 33 for C stocks). As the effect of tillage on these soil properties has been summarized in multiple meta-studies, it was chosen not to run all these studies separately by the model, but instead, model performance was assessed based on these meta-analyses (Luo et al., 2010; Powlson et al., 2014). After excluding studies on the effect of tillage and studies using parameters that are not simulated by the model, the number of studies we retained to test the model was 6 for N2O emissions, 2 for NO3- leaching and 12 for changes in SOC stocks. This includes one additional study on NO3- leaching (Hansen and Djurhuus, 1997) and one on C sequestration (Spiegel et al., 2018) that were added to the dataset. (2019-04-01) Hansen, E. M., and Djurhuus, J. (1997). Nitrate leaching as influenced by soil tillage and catch crop. Soil Tillage Res. 41, 203–219. doi:10.1016/S0167-1987(96)01097-5. Luo, Z., Wang, E., and Sun, O. J. (2010). Can no-tillage stimulate carbon sequestration in agricultural soils? A meta-analysis of paired experiments. Agric. Ecosyst. Environ. 139, 224–231. doi:10.1016/j.agee.2010.08.006. Powlson, D. S., Stirling, C. M., Jat, M. L., Gerard, B. G., Palm, C. A., Sanchez, P. A., et al. (2014). Limited potential of no-till agriculture for climate change mitigation. Nat. Clim. Chang. 4, 678–683. doi:10.1038/nclimate2292. Sandén, T., Spiegel, H., Stüger, H.-P., Schlatter, N., Haslmayr, H.-P., Zavattaro, L., et al. (2018). European long-term field experiments: knowledge gained about alternative management practices. Soil Use Manag. 34, 167–176. doi:10.1111/sum.12421. Spiegel, H., Sandén, T., Dersch, G., Baumgarten, A., Gründling, R., and Franko, U. (2018). “Soil Organic Matter and Nutrient Dynamics Following Different Management of Crop Residues at Two Sites in Austria,” in Soil Management and Climate Change (Elsevier), 253–265. doi:10.1016/B978-0-12-812128-3.00017-3.