EFFECT OF ADDING DRINKING WATER TREATMENT RESIDUALS AND SEWAGE SLUDGE ON P FRACTIONS IN SANDY SOIL

Accelerating the drive to re-use waste remnants due to growing stress and directives to recycle and re-use waste in addition to directives to soil improvement, resulting in water treatment residuals (WTRs) reuse that recently assorted as non-hazardous waste sludge, commonly using Alum [A12 (SO4)314H20] as coagulating and flocculating agents to precipitate undesired constituents. Disquiets over application WTRs to land are due to its supposed decreasing P availability and increasing AI toxicity with rising WTRs levels. Co-applying WTRs-sewage sludge can be beneficial for land application, especially sewage sludge high inherently in P and may act as a source of phytoavailable P, overcoming WTRs adsorptive capacity, by adjusting WTRs rate might prevent its negative effects and improve the quality of sandy soils. In pot experiment, the effect of co-applying WTRs-SS on the content of different forms of P in soil was investigated their effect as well on P & AI concentrations in radish plant and their uptake. The highest content of P in our soil was in Ca-bound P fraction while the lowest in soluble fraction, co-application of WTRs-SS increased total-P, moderately available and non-available P contents. Applying 5 gkg-1 of WTRs with P source (sewage sludge) to soil resulted in lower significant negative effects on available-P content and was effective in increasing hard-P content were increased by 84.18%. There is a negative linear relationship with increasing WTRs level and root, shoot P and shoot AI content (p < 0.05) and no symptoms for P deficiency or AI toxicity in radish plant with WTRs application.