Soil Mapping in Bangladesh

Electromagnetic induction (EMI) survey was conducted in the terrace and floodplain soils of Bangladesh by using a soil sensor, EM38. The soil apparent electrical conductivity (ECa) readings in the vertical orientation (ECa-V) of measurement ranged from 40 to 64 mS m-1 while readings in the horizontal orientation (ECa-H) ranged from 32 to 53 mS m-1 in the terrace site. In the floodplain site, the ECa-V readings ranged from 33.8 to 47.4 mS m-1 and ECa-H readings from 35.1 to 50.8 mS m-1. The EM38 response to soil conductivity was relatively higher for the vertical orientation than the horizontal orientation in the terrace site. But in the floodplain site, the ECa-H response was slightly higher than the ECa-V. In the terrace site, the ECa readings correlated best with soil property such as top-, sub-, and deepsoil texture (clay and sand), and topsoil chemical property, i. e. pH, CEC, Ca2+ and Mg2+. In the floodplain site, the ECa readings correlated best with top- and deepsoil texture, and topsoil organic C. A modest correlation was found in the terrace site between ECa-V and the subsoil clay (r = 0.78), and ECa-V and the subsoil sand (r = - 0.84).