Solar desalination for sustainable brackish water management in arid land agriculture

An agricultural facility aimed at sustainable production of crops in arid environments was built and tested in Hatzeva, Israel. The facility relies on solar-powered desalination with nanofiltration membranes to treat the local brackish water (EC=2.32 dS m^-1) and produce high-quality irrigation water (EC=0.71 dS m^-1). Red beet, a salt-tolerant crop, was grown with the concentrate stream (EC=4.73 dS m^-1), eliminating the need for concentrate disposal and with potential net economic benefits. Agricultural experiments with variable irrigation water quality, application rate, and four staple crops (potato, maize, millet and sorghum) were conducted over two growing seasons between September 2010 and June 2011. The desalination plant operated at low pressure (4.3 bar) and energy consumption (1.37 kWh m^-3) and with little maintenance over the entire study period. The results of the agricultural experiments consistently showed that irrigation with desalinated water promoted more efficient use of resources such as water and inorganic fertilizers. A reduction of 25% in the irrigation rate and use of fertilizers compared with best-practice guidelines was achieved with desalinated water, with no detectable detrimental effect on the marketable yield. On the contrary, a statistically significant yield increase was observed for sorghum (+10%). An increase in water productivity with desalinated water was observed for all four staple crops.