Soil Quality As Affected By Long Term Irrigation With Raw Wastewater

Abstract

There is consensus in the research community on the effect of irrigation with treated wastewater on soil properties and the accumulation of heavy metals in the soil. Studies that show the effect of irrigation with untreated wastewater(RWW)and evaluation health risk Index of heavy metals accumulation are very important and limited studies. This research was conducted in Palestine to examine the soil quality as affected by long-term irrigation with raw wastewater. A total of 44 soil, plant and water samples were randomly taken from Wadi al-Far'a; a region with a long history of RWW irrigation. The samples comprised 14 composite surface soil samples, 20 edible parts equally representing from two vegetable crops zucchini (Pepo gourd) and eggplant (Solanummelongena), and 10 irrigation water samples. All samples were collected according to the standard methods during the period May-September 2020 and were chemically and physically analyzed. The results showed that soils irrigated with RWW over the long term contained significantly higher concentrations of soil salinity, heavy metals, soil organic matter, and Nutrients available(N, p, and k. mg/L) compared to fields irrigated with fresh water. Heavy metal levels in water and soil samples were within the permissible limits, except for Cd concentration. Opposite behavior was seen for soil pH which decreased from 7.82 to 7.22, and 7.51, for RWW and Rain fed irrigation (Rf) respectively. The findings for determining the level of human exposure to heavy metals by using the Health Risk Index (HRI) for heavy metals accumulationin eggplant and zucchini crops were within the safe limits (<1). The presence of RWW nutrients within standards levels can increase land productivity, reduce fertilizer needs, and subsequently, cut down costs of the entire agricultural process. Our findings are critical for decision-makers in the Palestinian administration and other nations who are developing a plan for using Raw wastewater in irrigation for long-term agricultural management.