A controlled study of the effect of greywater (GW) irrigation on soil properties was conducted. Sand, loam and loess soils enriched with equal amounts of slow release fertilizer granules were planted with lettuce, and irrigated with fresh water, raw GW or treated GW. Greywater was treated using a recycled vertical flow constructed wetland, with a 12-hour hydraulic retention time. Soil samples were collected approximately every 10 days for the 40-day duration of the study. Soils were analysed for a number of physical, chemical and biological parameters. It was demonstrated that raw GW significantly increased the development of hydrophobicity in sand and loam soils. No increase in hydrophobicity was observed for the sand and loam irrigated with clean water or treated GW, or in the loess soil under all treatments. Fecal coliform (FC) were usually absent in soils irrigated with fresh water or treated GW, but found in significant numbers in raw GW irrigated soils. This study demonstrates that irrigation with raw GW may have a negative impact to soil properties. Additionally, a low-cost wetland treatment system eliminated the potential negative impact of GW on the soil.
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