Wednesday, November 15, 2006

Saline drainage water can be managed by growing forages.

Stephen R. Kaffka1, Murshidul Hoque1, and John Maas2. (1) Department of Plant Sciences, One Shields Avenue, University of California, Davis, CA 95616, (2) University of California, One Shields Avenue, Department of Vetrinary Medicine, Davis, CA 95616

Soil salinity and saline water tables in the western San Joaquin Valley of California threatens crop production.  Without a means of disposing saline drainage water, increasing amounts of farm land will become unusable.  To evaluate drainage water reuse, we tested whether saline-sodic drainage and other waste waters can be used for forage and livestock production at a 30 ha acre site in Kings County.  Bermuda grass (Cyanodon dactylon) was planted in 1999 and grazed rotationally. Livestock trials were carried out for three years (2001-2003). Forage sampling occurred at sites reflecting soil variation.  Samples were analyzed for quality and mineral content.  Bermuda grass grew well at moderate salinity levels up to ECe levels of approximately 20 dS m-1. Biomass at the start of grazing during summer varied from 1.5 Mg DM ha-1 to 2.5 Mg DM ha-1.  On a hay basis, forage CP contents averaged 9.0 %, (range: 4.2 to 22.1%), ADF: 29.6 % (range:  20.7 to 42.3), B: 245.4 mg kg-1 DW (range: 73 to 1004), Mo: 1.44 mg kg-1 DW (range: 0.3 to 5.3), Cu:Mo ratios averaged 5.2. CP and trace element content were greater in the upper portion of the canopy selected by cattle. Forage quality data for Mellilotus officianalis and Koschia scoparia are also presented.  Intake by cattle was 40 to 60 % of standing biomass, depending on variable stocking rates and management. Unsupplemented average daily gains were 0.75 kg d-1 in year 3, but less in years 1 and 2.  No adverse livestock health effects were observed.