Local Calibration of TDR Measurements for Determining Water and Organic Carbon Contents of Peaty Soils

Soil Systems

article

Claudia Kalla Nielsen¹  Anton Gårde Thomsen¹ 

[1] Department of Agroecology, Faculty of Technical Sciences, Aarhus University;CBIO, Centre for Circular Bioeconomy, Aarhus University

关键词: time domain reflectometry;    peatland;    organic carbon;    peaty soil;    water content;    soil moisture;   

DOI  :  10.3390/soilsystems7010010

学科分类：电子与电气工程

来源: mdpi

【 摘 要 】

Time domain reflectometry (TDR) measurements of the volumetric water content (θ) of soils are based on the dielectric permittivity (ε), relating ε to θ, using an empirical calibration function. Accurate determination of θ for peaty soils is vital but complicated by the complexity of organic soils and the lack of a general calibration model. Site-specific calibration models were developed to determine θ from TDR measurements for a heterogenous peatland across gradients of peat decomposition and organic carbon (OC) content; derived by soil organic matter conversion. The possibility of predicting OC contents based on the corrected θ (θcor); ε; electrical impedance (Ζ); and a categorical predictor variable was explored. The application of plot-specific and local area calibration models resulted in similar results. Compared to common calibrations, the threshold for accurate determination of θ was at ε = 5; with higher ε underestimating θ by up to 25%. Including the von Post degree of peat humification as a bioindicator, the OC content could be modelled across the area and the full range of θ with an accuracy of ±1.2% for 496 measurements. In conclusion, a strong indication was found for determining OC in peatlands in situ using TDR and a site-specific calibration model for θ together with indices of peat decomposition.

【 授权许可】

CC BY