Keywords: alum sludge-soil solution, soil testing, alkaline soils, phosphorus availability, water treatment residuals, wheat yield, phosphorus, aluminium, solid waste management, alum sludge, agronomic performance, alkaline soils
Land application of Water Treatment Residuals: effect on wheat yield and the availability of phosphorus and aluminium
Water Treatment Residuals (WTR) can be a potential source for available phosphorus (P) and Al, but the influence of WTR rates on the dynamics of available P and Al and plant uptake in alkaline soils are not well documented. Our objective was to evaluate the effects of WTR (Alum-sludge) on the agronomic performance of wheat crop grown in alkaline soils as well as P and Al availability and extractability. Wheat (Triticum aestivum L) plants were grown in three alkaline soils amended with WTR at five rates. After 13 weeks, plant shoots, panicles and roots were harvested separately and P and Al were measured. Increases of 246, 32% and 43% in total dry matter yield were achieved as a result of applying 30 g kg−1 WTR to sandy, clay and calcareous soils respectively. The trend of P concentration in different parts of wheat plants in response to applied WTR was negative quadratic (P < 0.01). The application rates of WTR used in this study did not increase extractable Al in amended soils >6 mg Al kg−1. Therefore, slight increases in available Al from application of WTR should not have adverse effects on soils or plants.