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Three‐Dimensional Mapping of Organic Carbon using Piecewise Depth Functions in the Red Soil Critical Zone Observatory
Author(s) -
Song Xiao-Dong,
Wu Hua-Yong,
Liu Feng,
Tian Jian,
Cao Qi,
Yang Shun-Hua,
Peng Xin-Hua,
Zhang Gan-Lin
Publication year - 2019
Publication title -
soil science society of america journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.836
H-Index - 168
eISSN - 1435-0661
pISSN - 0361-5995
DOI - 10.2136/sssaj2018.11.0447
Subject(s) - topsoil , soil science , subsoil , soil carbon , borehole , environmental science , saprolite , piecewise , total organic carbon , geology , hydrology (agriculture) , soil water , mathematics , geotechnical engineering , mathematical analysis , ecology , biology
Core Ideas A piecewise depth function was fitted for three‐dimensional simulation of organic C. Regolith depth was used as a depth constraint. Topsoil organic C maps were utilized as covariates and benefited the three‐dimensional simulation.Organic carbon ( OC ) plays a pivotal role in earth surface systems. However, current three‐dimensional (3D) mapping studies usually focus on a soil depth of 1 m rather than the depth to the bedrock. A top‐down method using piecewise depth functions was proposed to fit the OC vertical decline patterns in a subtropical catchment in southern China. The vertical variation in OC was greatly affected by the heterogeneous topsoil due to natural processes and anthropogenic disturbances. Thus, topsoil OC maps were produced and utilized as covariates to indicate the OC decline rates and to benefit the 3D OC simulation. A distribution map of the underground critical zone thickness (UCZT) was applied as a lower boundary for the 3D simulation. Six widely used mapping techniques were performed to predict the spatial distribution of topsoil OC and depth function parameters. The overall cross‐validation results showed a root mean squared error (RMSE) of 1.7 g kg –1 and a ratio of performance to deviation (RPD) of 1.82. Given limited boreholes, validation showed that the depth function performed better in the lower part (>1 m) than in the upper part (<1 m). The proposed framework could holistically employ sufficient topsoil samples and limited boreholes and provides a promising solution to simulate the 3D information of subsurface systems. We anticipate that continuous 3D OC maps can be integrated with other critical zone information to elucidate the complex interactions of various processes and to support potential service management decisions.