Pedosphere 17(2): 246--256, 2007
ISSN 1002-0160/CN 32-1315/P
©2007 Soil Science Society of China
Published by Elsevier B.V. and Science Press
| Calibration of soil electromagnetic conductivity in inverted salinity profiles with an integration method |
YAO Rong-Jiang , YANG Jin-Song and LIU Guang-Ming |
| Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008 (China). E-mail: rjyno@issas.ac.cn |
| ABSTRACT |
| Various calibration methods have been propounded to determine profiles of apparent bulk soil electrical conductivity (ECa) and soil electrical conductivity of a saturated soil paste extract (ECe) or a 1:5 soil water extract (EC1:5) using an electromagnetic induction instrument (EM38). The modeled coefficients, one of the successful and classical methods hitherto, were chosen to calibrate the EM38 measurements of the inverted salinity profiles of characteristic coastal saline soils at selected sites of Xincao Farm, Jiangsu Province, China. However, this method required three parameters for each depth layer. An integration approach, based on an exponential decay profile model, was proposed and the model was fitted to all the calibration sites. The obtained model can then be used to predict EC1:5 at a certain depth from electromagnetic measurements made using the EM38 device positioned in horizontal and vertical positions at the soil surface. This exponential decay model predicted the EC1:5 well according to the results of a one-way analysis of variance, and the further comparison indicated that the modeled coefficients appeared to be slightly superior to, but not statistically different from, this exponential decay model. Nevertheless, this exponential decay model was more significant and practical because it depended on less empirical parameters and could be used to perform point predictions of EC1:5 continuously with depth. |
| Key Words: coastal saline soils, electromagnetic conductivity, exponential decay model, integration calibration method, inverted salinity profiles |
| Citation: Yao, R. J., Yang, J. S. and Liu, G. M. 2007. Calibration of soil electromagnetic conductivity in inverted salinity profiles with an integration method. Pedosphere. 17(2): 246-256. |
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