Calculating the Long Term Effects on Soil Salinity
Abstract
Irrigating with saline groundwater may result in unsustainable levels of salt accumulation in the soil profile. This study uses field measurements in the Macalister Irrigation District of Gippsland, Victoria to test an analytical method for predicting the soil salinity from the salinity of irrigation water. The analytical method is based on a simple water and salt balance approach developed by the UN Food and Agriculture Organisation (Ayers and Westcott, 1985).
Soil salinity was measured at five sites irrigated for up to ten years with groundwater ranging in salinity from 2,252 µS/cm to 7,350 µS/cm. Calculated results using the UN Food and Agriculture method were compared to the measured field results for the same site. The interpretation of the field results was complicated by the likely addition of salt to the surface soils from a near surface watertable. However, the measured and calculated soil salinities compared reasonably well when the influence of the water table was taken into account. Appropriate input values to the analytical approach were recommended based on the comparison. The result is a greater degree of confidence in the prediction of the likely future soil salinity resulting from irrigation with saline water.
Authors
Andrew Harrison, Susana Hayes, Kate Hook