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Mapping Soil Moisture Content Variability Using Electromagnetic Induction Method

Published by the American Society of Agricultural and Biological Engineers, St. Joseph, Michigan

Citation:  9th International Drainage Symposium held jointly with CIGR and CSBE/SCGAB Proceedings, 13-16 June 2010  IDS-CSBE-100204.(doi:10.13031/2013.32155)
Authors:   A Farooque, Q Zaman, A Schumann, A Madani, D Percival, T Esau
Keywords:   Soil moisture, variability, EMI, irrigation, TDR, DGPS, GIS

In agricultural fields, large spatial variations in soil water content are associated with soil heterogeneities, topography, land cover, evapotranspiration, and precipitation. Detailed georeferenced maps would be useful to manage soil moisture according to soil variability to assess drainage and sub-irrigation requirements within wild blueberry fields. Two fields were selected in central Nova Scotia and a grid pattern of sampling points was established at each experimental site based on the geostatistical analysis of the ground conductivity survey data. The volumetric moisture content was determined for each grid point (n=86 for field 1 and n=56 for field 2) from both fields using TDR. The ground conductivity was measured and recorded with Dual EM at same sleeted grid points. Two comprehensive surveys were conducted in those fields to measure ground conductivity for moisture estimation in real-time using DualEM and a differential global positioning system. Linear regression analysis showed that ground conductivity was significantly correlated with the measured moisture content (R2 ranged from 0.85 to 0.90) in both fields. The accuracy of the estimated values from the DualEM data was calculated as root mean square error (RMSE: 2.66 and 3.63 for F1 and F2, respectively). The estimated soil moisture maps showed substantial variation in selected fields. The slope of both fields was also mapped using automated slope mapping system. The moisture and slope maps were overlaid representing high moisture content in low lying areas and steep slope areas having less moisture content. This information could be used to assess drainage requirements as well as to schedule site-specific sub-irrigation within fields.

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