Tuesday, November 6, 2007 - 9:45 AM
202-2

Detection of Subsoil Compaction in Agricultural Loess Soils by Electromagnetic Induction Probing.

Gunnar Hoefer1, Joerg Bachmann2, Karl Heinrich Hartge2, Hartmut Stützel3, Volker Gundelach4, Sven Altfelder5, Ursula Noell6, Jürgen Boess7, and Wilhelmus Duijnisveld5. (1) Herrenhaeuser Strasse 2, Institute of Soil Science, Leibniz Universitaet Hannover, 30419 Hannover, (Non U.S.), GERMANY, (2) Institute of Soil Science, Leibniz Universitaet Hannover, Herrenhaeuser Strasse 2, 30419 Hannover, Germany, (3) Institute of Biological Production Systems - Vegetable Systems Modelling, Leibniz Universitaet Hannover, Herrenhaeuser Str. 2, 30419 Hannover, Germany, (4) Applied Airborne and Ground Geophysics, Federal Institute for Geosciences and Natural Resources, Stilleweg 2, 30655 Hannover, Germany, (5) Soil Water, Solute Transport, Federal Institute for Geosciences and Natural Resources, Stilleweg 2, 30655 Hannover, Germany, (6) Geophysical Methods for Resource Management, Federal Institute for Geosciences and Natural Resources, Stilleweg 2, 30655 Hannover, Germany, (7) Agriculture and soil protection, land use planing, State office for mining, energy and geology in Lower-Saxony, Stilleweg 2, 30655 Hannover, Germany

The regionalization of subsoil compaction on the field scale is still an open problem. This is mainly because selective and specific measurements for a location are representing only the local compaction state of the soil while ignoring the spatial variability of physical soil properties. Non-destructive probes, on the other hand, provide a better spatial resolution but do in general not show the state of mechanical stress.

Apparent electric conductivity (ECa) is considered as an easy measurable parameter which is potentially able to detect inhomogeneities in the field which can, in turn, be used to select specific locations for subsequent investigations regarding the compaction state of the soil.

An easy-to-apply method which measures the apparent electrical conductivity (ECa) of soil is performed with the EM38 probe (Geonics, Canada). Subsoil compaction was assessed by the penetration resistance (PR) (Penetrologger, Eijkelkamp, the Netherlands) from the soil surface down to 0.8 m soil depth with a vertical resolution of 0.01 m. The fields under study are located south of Hannover, in the northwest of Germany. We measured at approximately 10,000 locations the apparent electrical conductivity and at 5,000 locations the penetration resistance. Measurements were taken in April 2005 up to April 2007. Further, we used at one site a Ground Penetrating Radar to add detailled information of soil discontinuities on a small scale.

In general we found a strong correlation between the values of the Penetrologger and the signal of the EM38, especially in the area with high values of penetrations resistance. The additional results from the Ground Penetrating Radar back the results from the PR measurement and partly the spatial variety of the ECa results. This leads us to the conclusion that the geophysical based EM38 technique could be a detector for the regionalization of subsoil compaction in soils consisting of homogeneous material


Back to Compaction Assessment and Effects
Back to S06 Soil & Water Management & Conservation

Back to The ASA-CSSA-SSSA International Annual Meetings (November 4-8, 2007)