Characterization of pressmud, and evaluating the growth, yield and metal uptake response of wheat to pressmud and phosphate fertilizer application on a metal-contaminated soil

Abstract

Abstract Use of industrial and municipal wastewater for crop irrigation adds toxic metals to soils. This causes a decline in crop productivity and metal contamination of food crops. This study characterized pressmud (PM), and evaluated growth, yield and grain metal accumulation response of wheat to PM and single super phosphate (SSP) application on a metal-contaminated soil. The mean values of different parameters of eight PM samples collected different sugar industries were; EC 4.81 dS cm-1, pH 5.74, cation exchange capacity 66 meq 100 g-1, nitrogen 2.1%, P2O5 2.90%, K2O (0.87%), organic carbon 35.09%, lead 1.32 mg kg-1 and cadmium 8 µg kg-1. Furthermore, a preliminary soil survey conducted on eight fields continuously irrigated with wastewater, and the soil having highest DTPA extractable lead (5.022 mg lead kg-1) and cadmium (0.26 mg cadmium kg-1) concentration was selected for pot experiment. PM (control, 10 and 20 g kg-1 soil) and SSP (0 and 250 mg kg-1 soil) were uniformly mixed with soil. PM at both levels exhibited similar improvement in growth and yield attributes of wheat. The highest increases of 38, 37 and 131% in tillers, straw biomass and grain yield were observed with PM addition than control. The application of SSP improved yield at par as recorded with PM. Applying SSP in combination with PM did not exhibited added benefit in terms of increase in growth and yield. The increase grain yield on PM-amended soil was linked to improved nutrient acquisition and decreased metal accumulation. PM-amended soil had higher available nitrogen, phosphorus and potassium concentration than control, which subsequently resulted in 2.96. 1.85 and 2.42-fold respective increase in their uptake by grains. The plants showed clear metal toxicity symptoms on leaves, while addition of PM alleviated those symptoms. Moreover, PM decreased accumulation of Cd and Pd in grains by 48 and 56%, respectively than control, while SSP effect was non-significant. Thus, PM improves wheat productivity through enhancing nutrient uptake and lessening metal absorption on a metal-contaminated soil.