variable,description,unit site_id,Sampling point identifier,- depth_cm,Soil depth,cm NH3_flux_nmol_m2_s,Ammonia flux,nmol m-2 s-1 VWC_percent,Volumetric water content,% soil_temperature_C,Soil temperature,C NH4_mg_kg,Ammonium,mg kg-1 NO3_mg_kg,Nitrate,mg kg-1 total_N_percent,Total nitrogen,% humus_percent,Humus,% H_concentration_mol_L,Hydrogen ion concentration,mol L-1