Agriculture 1 Biogeochemistry 1 C:N ratio 1 Carbon dioxide 1 Drainage 1 Humification 1 Humification index 1 Humus compound 1 Humus compounds Organic carbon 1 Organics 1 Peat 1 Peatland 1 Secondary humification 1 Soil organic matters 1 Soil sample 1 Soil surveys 1 Soils 1 Total nitrogen 1 Wetlands 1 humification 1 organic matter 1 peatland 1 residence time 1 siltation 1 soil carbon 1 soil organic matter 1