Management of salinity and sodicity in a land FILTER system, for treating saline wastewater on a saline-sodic soil

The FILTER (Filtration and Irrigated cropping for Land Treatment and Efflue nt Reuse) technique was developed to provide a sustainable system for treat ment of saline sewage effluent on naturally occurring saline and/or sodic s oils. Potentially, it can also be used to ameliorate soils that are salinis ed by inappropriate application of saline effluent on soils with impeded dr ainage. The FILTER technique involves using the nutrient-rich effluent for irrigated cropping combined with removal of excess water from the root-zone through a subsurface drainage system, during wet weather and winter period s when evapotranspiration demand is low. This paper describes the changes in salinity and sodicity in FILTER plots u sed for land application of saline sewage effluent on a heavy clay soil wit h restricted drainage, at the Griffith City Council sewage works site. The field experiments consist of trials conducted on four 1-ha plots, over an 1 8-month period. The pre-FILTER soil chemical characteristics and their chan ges with FILTER operations were measured. In addition, the volumes and the chemical properties of the effluent applied and subsurface drainage water p assing through the soil were monitored. These data are used to explain the salinity and sodicity changes within the FILTER soils, and their potential effects on soil stability. Management options to minimise salinity and sodi city to provide a sustainable system are suggested.