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Remediation of Crude Oil Contaminated Soil, Using Organic Supplement: Effects on Growth and Heavy Metal Uptake in Cassava ( Manihot esculenta Crantz)
OSU, SR; UDOSEN, IR & UDOFIA, GE
Abstract
Field experiments were conducted in 2016 and repeated in 2017 to evaluate the effectiveness of Oil
Palm Bunch Ash (OPBA) and Dried Poultry manure (DPM) as organic supplement, applied singly and in combination on
growth properties and heavy metal uptake of cassava cultivars grown in crude-oil contaminated soil of the Niger Delta
Region, Nigeria. There were four different organic amendments viz: DPM, OPBA, OPBA +DPM and control using TMS
30572, NR8082 and local variety as test crops. Results were elaborated statistically with the use of three-by-four factor
variance analysis with ANOVA. Effect of various application of amendment on morphometric parameters of cultivars
revealed in 2017 that at 36 weeks after sprouting (WAS), DPM and OPBA +DPM significantly (P≤ 0.05) enhanced plant
heights of TMS 3572 and LV but had no influence on number of nodes, stem girth and leaf area. However, the interactions
resulted in significant (P≤ 0.05) uptake and concentration of the heavy metals Fe, Cu, and Pb in leaves and Fe in roots of
TMS30572 and NR8082, indicating efficient metal removal by these varieties. Results of amendment also revealed
remarkable increment in bacterial and fungal (from 104 to 106 and 103 to 104) populations respectively, correlating with
reduction in soil total petroleum hydrocarbon (TPH) from 156.45 mg/kg to 146.73 mg/Kg. This is observed to diminish
oil toxicity and improve soil status. The response of these cassava varieties to crude oil contamination appears to be
optimistic. Consequently crop farmers are adviced against planting cassava and other arable crop at crude oil impacted
soil for the risk of uptake of heavy metal in crop tissues.
Keywords
Remediation; Heavy metal; Oil-contaminated soil; Organic amendment; Growth properties; Cassava
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