The publication of this Handbook was supported by the Russian Federation

Soil mapping with the use of  electromagnetic induction
The EMI method is based on field measurements of  the apparent electrical conductivity (ECa) 
with the use of  a portable device that can be carried by hand or attached to a tractor (Fig. D.1). 
The data are transferred from the device to a portable computer along with GPS coordinates that 
are recorded in real time. The Geonics EM-38 ground conductivity meter (Canada) is the most 
common device for measuring electrical conductivity through EMI, which allows the assessment 
of  soil salinity within a layer 1-1.5 m thick. A more detailed description of  this method can be 
found in published papers [9, 11]. Similar devices include the DUALEM-421 sensor that has been 
recently introduced in practice. This sensor is capable of  measuring the ECa at six different depths, 
which allows creation of  multidimensional (3D and even 4D) models of  salt distribution in soils 
[21] (Fig. D.2).

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Soil salinity manаgement manual | Part II.Tutorial examples, guidelines and exercises 
Fig. D.1. A tractor equipped with an EM-38 ground conductivity meter and a satellite navigation 
system, with direct data transfer to a portable computer (USDA Salinity Lab, Riverside, USA).

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Annex D.Innovative methods of mapping and monitoring saline and alkaline soils 
Fig. D.2. The vertical distribution pattern of the apparent electrical conductivity ( 
σa, mSm/m) 
measured using a DUALEM-421 sensor in its horizontal ( Hcon) and perpendicular ( Pcon) positions, 
with different distances between its transmitter and receiver: a – 1 m, b – 2 m, c – 4 m.