• journal_title：Vadose Zone Journal
• Contributor：Gonzalo Martinez ; Karl Vanderlinden ; Rafaela Ordóñez ; José L. Muriel
• Publisher：Soil Science Society of America
• Date：2009-
• Format：text/html
• Language：en
• Identifier：10.2136/vzj2008.0123
• journal_abbrev：Vadose Zone Journal
• issn：1539-1663
• volume：8
• issue：3
• firstpage：586
• section：ORIGINAL RESEARCH

Ancillary information, such as apparent electrical conductivity (EC_a), can improve the spatial and temporal estimation of soil properties. The purpose of this study was to determine if EC_a could be used for the spatial characterization of soil organic C (SOC) within a long-term tillage experiment. Apparent electrical conductivity was measured using an electromagnetic induction sensor, the EM38DD, and its predictive potential for mapping SOC was evaluated. The EC_a maps showed clear differences between the conventional tillage and direct drilling plots, with higher EC_a and SOC in the direct drilling plots. A normalized EC_a difference (ΔEC_a), calculated as the difference between the normalized vertical and horizontal dipole EC_a values (EC_aV and EC_aH, respectively) successfully classified the SOC observations according to their corresponding management systems. Maps of ΔEC_a (FKM1) and EC_aV and EC_aH (FKM2) classified by fuzzy k-means accounted for 30% of the total SOC variability, whereas the individual plots and management strategy explained 44 and 41%, respectively. Simple kriging with local varying means using either FKM2 or plot-average SOC as secondary information reduced the RMSE by 8% and increased the efficiency index by about 70% compared with ordinary kriging. Despite the low point-to-point correlation between EC_a and SOC, EC_a was shown to be useful for the spatial estimation of SOC.