Field performance of halophytic species under irrigation with saline drainage water in the San Joaquin Valley of California

Halophytes have been considered as potential crops for the reuse of saline drainage water (DW) in the western portion of California's San Joaquin Valley. This management strategy can reduce drainage volumes through plant water consumption and concentrate salts and other contaminants prior to discharge of the final effluent into a solar evaporator. A field study was conducted in order to assess the performance of six halophytes species Salicornia bigelovii, Atriplex lentiformis, Distichlis spicata, Spartina gracilis, Allenrolfea occidentalis and Bassia hyssopifolia, under long-term irrigation (4-6 years) with saline (Na-sulfate dominated) agricultural DW. The suitability of the halophytes was evaluated in terms of biomass production, water consumption, mineral composition and nutritional quality as animal fodder. Results indicate that all species grew well under highly saline-sodic soil conditions (average ECe, = 28.6 dS m(-1); SAR = 39.4), with average standing biomass ranging between 3.8 and 17.4 tons dry matter (DM) ha(-1) depending on species. Under frequent irrigation in drainage lysimeters, daily evapotranspiration (ET) rates for the halophytes were 1.02-1.18 times higher than reference ET (ET0). For S. bigelovii daily ET rates were similar to that of a non-halophytic grass, Festuca arundinacea, irrigated with fresh water (7.5 mm day(-1) vs. 7.4 mm day(-1). Mineral composition and forage quality data indicate several drawbacks associated with the utilization of DW-irrigated halophytes as forages. All species had metabolizable energy (ME) values lower than 7 MJ kg(-1) DM, the minimum value considered to be acceptable quality for most classes of ruminant animals. Additionally, halophyte tissues contained high levels of salts (total ash content ranged between 6 and 52%), and accumulated Na+, Cl-, SO42-, NO3-, B and Se to levels close or above the maximum tolerable levels (MTL). Halophytes tested in this study can be classified as very low quality forage for which long-term grazing is not recommended. However, they could be used as a fodder supplement, if rations can be controlled. (C) 2013 Elsevier B.V. All rights reserved.