Monitoring soil moisture status in a Black Vertosol on the Liverpool Plains, NSW, using a combination of neutron scattering and electrical image methods

Electrical image data were used to estimate soil moisture content beneath smectite-dominated black Vertosol in the Liverpool Plains catchment in northern New South Wales. Measurements carried out over a range of soil moisture conditions included: water use by lucerne sown into a full pro. le, recharge of profiles after lucerne and long fallow after a cereal crop. Measurements were repeated approximately every 2 months between September 2000 and August 2001. Estimates of bulk electrical conductivity (EC), determined from inversion of apparent conductivity electrical images, were compared to soil moisture measurements made using neutron access tubes. A correlation of 0.77 (n = 228, P< 0.0001) between the 2 datasets indicates that electrical imaging can be used to satisfactorily predict bulk moisture content in soils of this type. Interpretation of the bulk EC images indicates drying of the soil profile to 6 m depth beneath lucerne.