Soil classification and salinity mapping for determining restoration potential of cropped riparian areas

Restoration and management of riparian areas have recently become important issues. Soil and salinity surveys are required before planning restoration activities and land-uses if the riparian area is salt-affected. In this study, we characterise the soils and salinity conditions of a riparian area that underwent irrigated agriculture with significant soil salinisation, to assess the general site suitability for riparian restoration and potential land-uses. Throughout the area, 19 profiles were described and classified and 95 soil samples were collected for their chemical and physical characterisation. The salinity of the 35-ha presumably salt-affected area was analysed by reading the bulk soil electrical conductivity (ECa) with the hand-held electromagnetic-induction sensor Geonics-EM38 at 558 locations and by measuring the electrical conductivity of the saturation extract (ECe) and sodium adsorption ratio (SAR) of 60 soil samples collected at 30 of those locations. The regression of ECe on EM readings predicted ECe with R-2 >0.92 at the 0-100cm soil depth. The geo-referenced soil classification (three soil units were established) and salinity maps identified the soil constraints for the area's restoration potential. The major limiting soil factors were soil salinity, sodicity and waterlogging in the southern half of the soil unit #3, and soil compaction in most of the area. The value of those limiting factors, along with differences in soil texture, as a means of assessing restoration potential of riparian vegetation and for identifying suitable land-uses for the three soil units was discussed. Agro-forestry, planned grazing, recreational and educational land-uses are possible for the site. Copyright (C) 2007 John Wiley & Sons, Ltd.