Fresh Enough for the Farm?

摘要

As freshwater resources dwindle, purified waste-water is increasingly discussed as a supplement for such high-volume uses as crop irrigation. In a 15-year field-scale test of this prospect, Assouline and Narkis studied the soil properties of an irrigated avocado farm in Israel; one side of the farm received natural fresh water, while the other received treated domestic wastewater that by most accounts was quite similar to the natural source but had increased dissolved organic matter, salinity, and suspended solids. Over the study period, several hydraulic properties of the clay-rich soil degraded in the plots that received treated wastewater, to the point that irrigation events created a smaller but more saturated volume of wetted soil.