CHANGES IN SUBSURFACE DRAINAGE WATER SALINITY AND BORON CONCENTRATIONS

The electrical conductivity (salinity) and boron concentrations of subsurface agricultural drainage effluent are analyzed. The effluent is from drainage systems ranging from 0 to 40 years of age, located on irrigated saline soils in the San Joaquin Valley, California. Data collected from 1962 to 1990 verifies that the equation developed between 1959 and 1962 is valid for use in predicting the quality of effluent that will be discharged from artificial subsurface drainage systems installed in irrigated agricultural soils of the San Joaquin Valley, California. The work is useful in that it demonstrates the predictability of the quality of subsurface drainage effluent from drains installed in irrigated land. Such relationships are important in arid areas of the world where reclamation of irrigated land is required, particularly when there is growing concern about the sustainability of irrigated agriculture on saline soils and the environmental impact of saline drainage effluent.