Tuesday, November 6, 2007 - 4:10 PM
145-8

Salinity Management and Cropping Systems.

S.R. Kaffka, Dept. Plant Sciences, Universidy of California, Davis, CA 95616, Stephen Grattan, 231 Veihmeyer, University of California-Davis, University of California-Davis, Coop. Ext. Dept. of LAWR, Davis, CA 95616, and Dennis L. Corwin, USDA-ARS, United States Salinity Laboratory, 450 West Big Springs Rd., Riverside, CA 92507-4617.

The difficulties with capturing and reusing drainage water for crop production in the WSJV involve the technical challenge of maintaining the productivity of the land to which it is applied for irrigation, the presence of trace elements like selenium and boron in drainage waters that pose ecological problems, and a number of institutional or policy barriers to an integrated approach to salinity/drainage issues. Nevertheless, drainage water management has been the subject of research for two decades and a number of possible approaches have emerged. A few research and development projects have been created that indicate that land-based management solutions for saline drainage water may be feasible. For example, we have documented perennial grass forage production levels of 7.5 to 10 tons/ac on variously salt affected lands using saline irrigation water and low levels of fertilization over the 1999 to 2006 period. Annual hay, grain plus straw, and oilseed crops have been produced on salt-affected lands where no irrigation is allowed using rainfall and crop uptake from subsurface shallow groundwater. With careful use, most of the salt affected land in the WSJV can be used sustainably to produce biomass or dedicated crops for conventional markets or for biofuel production. New technologies including precision agriculture and reduced tillage will facilitate farming under these conditions. Using drainage water on salt-tolerant crops will reduce the amount of drainage water to be managed in the WSJV by 80 to 90%. The nutrients in these waters will be beneficial for crop production. Any residual saline water will be concentrated in fewer places and will have higher concentrations of salts making it technically and ecologically easier to manage than widely distributed drainage sources. Larger areas of the valley will be better protected from groundwater degradation.