Environmental Science

Fresh Enough for the Farm?

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Science  02 Sep 2011:
Vol. 333, Issue 6047, pp. 1202
DOI: 10.1126/science.333.6047.1202-c
CREDIT: ISTOCKPHOTO

As freshwater resources dwindle, purified wastewater 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. These conditions may have contributed to smaller root zones that ultimately led to lower crop yields. Because some soil horizons responded differently to the treated wastewater, it is not yet clear if treated wastewater will have this effect on other soil types or if precipitation patterns across different regions buffer against soil degradation.

Water Resour. Res. 10.1029/2011WR010498 (2011).

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