Improving Crude Oil Contaminated Soil with Organic Amendments: Effect of Oil Palm Bunch Ash and Dried Poultry Litters on Soil Properties and Cassava Growth and Yields

Abstract

In this study, onsite field experiments were carried out to evaluate the effects of amending a crude oil polluted soil with oil palm fruit bunch ash (OPFBA), dried poultry litters (DPL), soil bacterial, physico-chemical properties, as well as the growth and tuber yield of cassava (Manihot esculenta CRANTZ) grown on the amended soils using standard techniques. Results of autotrophic bacteria counts revealed that nitrogen fixing bacteria (NFB) populations in soils treated with OPBA+DPL combined, OPBA and DPL singly, recorded high bioloads in the magnitude of 10⁵ , 10³ , 10⁵ CFU/g of soil respectively, whereas the group mean population was lower in the control soil (10³ CFU/g). Similar trends were observed for SRB, PSB, and THB. Results of aggregate growth showed that while the mean plant heights and number of nodes increased, stem girth and leaf area were observed to decrease in 2017 when compared with those of 2016. Apart from number of tubers and weights that showed increase under all amendment treatments, tuber girth and length decreased under DPL amendments in 2017. The average findings of several chemical and physical characteristics of crude oil polluted soil after amendments and subsequent cultivation demonstrated that the addition of DPL and OPBA fructifies the soil by increasing reduced or lost qualities. When the amendments were used, the concentrations of organic carbon, accessible phosphorus, Ca, Mg, Na, and K were greatly enhanced, while the Total Petroleum Hydrocarbon (TPH) content was significantly reduced. In this study, the application of combination DPL + OPBA yields the greatest results in terms of ameliorating the impacts of crude oil in cultivable soils, as it increases fertility parameters for better cassava production in Niger Delta soils. The technology has been shown to be cost effective, efficient, and environmentally friendly, as well as capable of resolving waste management issues.