Response of Maize (Zea mays) on Crude Oil Polluted Soil after One Month of Remediation with Spent Mushroom Substrate

The study was conducted to evaluate the influence of different levels of crude oil pollution remediated with spent mushroom substrate (SMS) on the growth of maize after one month of pollution. Composite soil samples randomly collected were polluted with Bonny light crude oil (v/w) at a concentration of 0%, 2%, 4% and 6% in a perforated plastic pots with 6 kg of top soil (0-20) cm. Ten percent of decomposed SMS was applied on each of the pots. A month after remediation, four seeds of Oba Super 11 maize variety were sown into each pot and later thinned to two after germination. The design was Complete Randomized Design consisting of six treatments and four replicates. After eight weeks of the study, results revealed a reduction in plant germination rate (60%) in polluted (SCM) against (87%) in non-polluted (SM) soil. Plant germination was highest (93.8%) on natural soil (SSM) amended with SMS. Amendment of the polluted soil with SMS improved the germination of the plant from 60% to 75%. There was a significant (P<0.01) decrease in plant height on polluted against natural soils. Amendment of the polluted soil with SMS slightly increased the height of the plant though not significant within the first six weeks of the study, however, a significant (P<0.01) increase was observed on the seventh and eighth weeks of the study. Pollution of the soil with crude oil revealed significant (P<0.01) reduction on some soil physico-chemical properties (available phosphorus, exchangeable cations (Ca, Mg and K), while a significant (P<0.01) increase was observed on total hydrocarbon content, total nitrogen, total organic carbon and total organic matter on the polluted over natural soil. Amendment of the polluted soil with SMS improved the nutrient status of the soil as there was significant (P<0.01) increase in the concentration of Ca, Mg, K, P and a reduction in the content of THC, TOC of the soil. Remediation of crude oil polluted soil, with spent mushroom substrate a month after pollution, improved soil fertility.