Water use, productivity and forage quality of the halophyteAtriplex nummulariagrown on saline waste water in a desert environment

The halophyteAtriplex nummulariaLindl. was grown in a desert climate in Tempe, AZ, for 3 years in outdoor drainage lysimeters. Plants were irrigated with two sources of waste water from an electric power plant: mildly saline (1149 mgl l−1total dissolved solids (TDS)) storm runoff collected in a pond, or brackish (4100 mg −1TDS) blowdown water from cooling towers. Plants were irrigated weekly with enough water to replace evapo-transpiration losses but leaching fractions were only 4–10%.Atriplex nummulariaperformed equally well on both water sources, even though soil solution salinity in the rooting depth profile ranged from 300–1000 mol m−3NaCl in lysimeters irrigated with blowdown water compared to only 40–90 mol m−3in lysimeters irrigated with pond water.Atriplex nummulariahad higher productivity, water use efficiency and consumptive water use than conventional forage crops in Arizona irrigation districts. Nutritional content of plant tissues was acceptable for use as a ruminant forage.Atriplex nummulariahad key traits desired in a plant for disposal of saline water: high consumptive use to minimize land area devoted to reuse; high salt tolerance, conferring the ability to grow under low leaching fraction to minimize discharge to the aquifer; and useful production