SOIL PETROLEUM CONTAMINATION AND UREA FERTILIZATION INHIBIT NUTRIENT RELEASE FROM WHITE CLOVER LITTER DURING DECOMPOSITION

Fresh litter from white clover, a petroleum contamination phytoremediator species, was buried in an uncontaminated soil as well petroleum contaminated soils with and without urea fertilizing for 6 months to evaluate the effects of petroleum contamination and urea fertilization on nutrient release from the litter over time. The results showed that petroleum contamination significantly inhibited the release of Cu, accelerated the release of Mn and had no obvious effects on the release of N, P, K, Zn, Fe, Mg and Ca from the litter. Fertilizing the contaminated soil with urea significantly inhibited the release of N, K, Cu and Mg from the litter and had no obvious effect on the release of the other nutrients. Although the soil petroleum contamination did not influence the release of most nutrients from the litter, urea fertilization potentially inhibited the nutrients release and it is not recommended to be applied in the petroleum contaminated soils along with phytoremediation.