Reuse of highly saline aquaculture effluent to irrigate a potential forage halophyte, Suaeda esteroa

We tested the feasibility of reusing saline aquaculture effluent to produce a salt-tolerant shrub (Suaeda esteroa) with potential as a forage crop. Plants were grown in sandy loam soil, in drainage lysimeters to determine forage yield, water use and capacity for nitrogen and phosphorus uptake when irrigated with highly saline (31 ppt NaCl) effluent from a tilapia culture system. Water was applied to soil three times per week at five rates, ranging in volume from 50 to 250% of the pan evaporation rate. Plant biomass increased significantly with increasing irrigation volume (P < 0.05). Due to higher plant growth, water consumption also increased with increasing irrigation volume (P < 0.05). Nitrate concentrations in water draining from the lysimeters decreased during the experiment and decreased with increasing irrigation volume (P < 0.05). Toward the end of the experiment, concentrations of nitrate in the leachate in the high volume treatments were below the mean limits set by the US Environmental Protection Agency for effluent discharge. Phosphorus concentrations in the leachate water increased during the experiment and increased with increasing irrigation volume (P < 0.05). We conclude that using high salinity aquaculture wastewater to irrigate halophyte crops can be a viable strategy for disposal of effluent, especially where phosphorus is not a limiting nutrient. (C) 1999 Elsevier Science B.V. All rights reserved.