EVALUATION OF POULTRY MANURE-BIOCHAR ADDITION TO STIMULATE OIL DEGRADATION IN SOIL
In this study, remediation of heavy metals; arsenic, cadmium, chromium, copper and lead,
and petroleum hydrocarbons in co-contaminated soil using in situ application of admixtures
of poultry manure and termite mound soil was examined. The contaminated soil with total
heavy metals content, MTot 110.69±3.08 mg.kg-1
(As 8.00±0.36 mg.kg-1
; Cd 10.83±0.33
mg.kg-1
; Cr 20.90±0.56 mg.kg-1
; Cu 43.43±0.99 mg.kg-1 and Pb 25.45± ±0.85 mg.kg-1
) and
total petroleum hydrocarbons content 208.30±0.62 mg.kg-1 was treated with admixtures of
poultry manure and termite mound soil of various compositions (0 – 100 wt% poultry
manure) and durations (30 – 120 days) of amendment application. Reductions in the levels
of total-extractable and bioavailable metal fractions and in residual total petroleum
hydrocarbons, plant (maize) uptake and transferability of heavy metals and changes in soil
enzyme activities were used as indicators of remediation end-point. It was found that in
comparison with unamended soil, marked reductions (in the range 64 -89%) were
associated with poultry manure/termite mound soil application to the contaminated soil. The
reduction in bioavailable metal fraction following amendment application was reflected in
corresponding reduced plant uptake, 18-fold by maize roots and 25-fold in transferability to
maize shoots as a result of the application of poultry manure/termite mound soil to the
contaminated soil. Degradation of petroleum hydrocarbons varied in apparent dependence
on the poultry manure content of the amendment and was almost quantitative (95%) with
application of amendment (100 wt% poultry manure) and duration of 120 days. Increased
levels of soil enzyme activities of several order of magnitude (67 – 500%) in comparison with
unamended soil accompanied application of poultry manure/termite mound soil amendment
to the contaminated soil. Restoration of soil quality (measured in terms of enzyme activities)
depended on the level of poultry manure component of the amendment material