Impact of Palm Oil Mill Wastes on Soil P

Palm oil mill wastes (POMWs), including palm oil mill effluent (POME), palm fruit fibre (PFF), and palm kernel shell (PKS), are major by-products of palm oil processing and are often discarded without proper treatment. This study evaluated the effects of these waste types on selected soil physical and chemical properties, and concentrations of bioavailable heavy metals (Cr, Pb, Zn, Cd) in Aguata Area, Anambra State, Nigeria. Soil samples were collected from three dumpsites and control sites across three depths (0–15 cm, 15 –30 cm, and 30 –45 cm). Standard laboratory protocols were employed, and data were analysed using ANOVA. Results showed that POME-treated soils had significantly lower clay content (20.8%) and higher porosity (53.9%) at the surface layer compared to PKS and PFF. POME also increased soil pH (6.84), organic carbon (2.54%), total nitrogen (0.22%), and exchangeable base cations more than other treatments. Heavy metal concentrations, particularly Pb (0.19 mg/kg) and Zn (0.50 mg/kg), were higher in POME-affected soils but remained within permissible limits. Overall, POME demonstrated the greatest potential for improving soil fertility, though with elevated environmental risks due to heavy metal buildup. These findings underscore the need for regulated application and pre-treatment of POMWs to optimize their benefits while minimizing ecological risks in agroecosystems.