Reuse/disposal of agricultural drainage water with high levels of salinity and toxic trace elements in central California.

Authors: Banuelos, Gary; Ayars, James; LIN, Z - Southern Illinois University

Submitted to: Book Chapter
Publication Type: Book / Chapter
Publication Acceptance Date: 10/1/2012
Publication Date: 11/15/2012
Citation: Banuelos, G.S., Ayars, J.E., Lin, Z.Q. 2012. Reuse/disposal of agricultural drainage water with high levels of salinity and toxic trace elements in central California. Zueng-Sang Chem (Ed) International remediation and management of soil & groundwater contaminated sites. pp. 207-215. National Taiwan Uni. Press, Taipei, Taiwan (Book Chapter)

Interpretive Summary: There is an increasing trend towards reusing poor quality waters for irrigated agricultural production systems. Sufficient evidence exists to support the concept of reusing saline water originating from agricultural drainage or from shallow groundwaters. Reusing poor-quality water for irrigation can serve two purposes – one is to dispose of drainage water that would otherwise be costly to be treated, and the other is to utilize poor-quality drainage water as a water resource for growing crops that have economic value. The objective of this review was to illustrate a plant-based agricultural drainage-water reuse system in the Westside of central California, with an emphasis on the role of soil and vegetation in operating a water reuse system in an environment having high levels of salt, B and Se. The tested plant species to be irrigated with drainage waters included; (salt-sensitive) lettuce, tomatoes; (moderately salt tolerant) cotton, canola, sunflower; (salt tolerant) saltgrass, pickleweed, cordgrass, eucalyptus trees, and final disposal site-a lined solar evaporator. The quantity and quality of drainage water decreased along the water reuse path. With subsequent usage increases in a sulfate-dominated salinity, soluble B and soluble Se in drainage water were observed. Unused drainage water was sprinkled into the solar evaporator. Successfully re-using drainage water for irrigation on salt and B tolerant crops not only disposes of drainage water that would otherwise be costly to discharge but also reduces the requirement for good-quality irrigation water. Although producing crops of economic value from poor quality waters enhances the long-term, acceptance of this water reuse strategy, salt and trace element build-up in the soils must be monitored.

Technical Abstract: Agricultural drainage waters in the western San Joaquin Valley of Central California contain high levels of salts, boron (B) and selenium (Se). Discharge of the drainage water directly into the Kesterson Reservoir in 1980's was hazardous to plants and wildlife. To investigate the plausibility of using plants as recipients for disposing of poor-quality drainage-waters, multi-year field studies were conducted to reuse drainage water on plants that are salt and B tolerant, and accumulate or stabilize soluble Se from the drainage water. Installation of subsurface tile drainage systems in cropping fields allowed drainage waters to be collected and subsequently reused on salt tolerant crops. The following tested plant species ranging from salt sensitive to salt tolerant were irrigated with drainage water; lettuce (Lactuca sativa), tomatoes (Lycopersicon esculentum), canola ( Brassica napus),cotton (Gossypium hirsutum L.), alfalfa (Medicago sativa L), sunflower (Helianthus annuus), salt grass (Distichlis spicata L.), pickleweed (Salicornia bigelovii Torr.) and eucalyptus trees (Eucalyptus camaldulensis). A lined solar evaporator pond was site of final disposal of residual drainage water. Each growing site had a subsurface drainage system installed 2 m below he soils surface. Water was collected and routed for irrigation of the subsequent crop through a central distribution manifold. Results showed the quantity and quality of drainage water decreased along the water reuse path, with increases in a sulfate-dominated salinity from 4.5 to 15.2 dS/ m; soluble B from 3.4 to 14.5 mg/L; and soluble Se from 0.08 to 1.18 mg/ L. This study successfully demonstrated the crop productivity of selected crops used for the recycling of drainage water varied quality and importantly shows that increased levels of salinity and trace elements need to be monitored in the waters, soil and in the crops produced with water reuse of drainage water produced in this region of Central California.