Responses of litter decomposition and nutrient release of Bothriochloa ischaemum to soil petroleum contamination and nitrogen fertilization

Abstract

To assess the effects of petroleum contamination or fertilization with nitrogenous fertilizer in contaminated soil on the litter decomposition of Bothriochloa ischaemum, a phytoremediating species, its litter was placed in litterbags and buried in uncontaminated soil, and petroleum-contaminated soil with and without urea fertilization (petroleum concentration: 45 g/kg, the ratio of soil C/N was adjusted to 25:1 after urea fertilization) for a 6-month decomposition experiment at consistent soil moisture and room temperature (20–25 °C). The results indicated that petroleum contamination significantly inhibited the overall decomposition (the turnover period was extended by 44.35%) and nutrient release (the release of P, K and Fe was inhibited, while the release of N and Zn was accelerated) of B. ischaemum litter, while N fertilization significantly intensified the inhibitory effects of petroleum contamination (significantly extended the turnover period of decomposition by 36.71% again and simultaneously inhibited the release of C, N, P and Zn). Consequently, this research suggests that additional measures should be simultaneously used with phytoremediation to alleviate the inhibitory effects of petroleum on B. ischaemum litter decomposition. However, fertilizing the contaminated soil with urea might cause potential disadvantages, and it should not be applied in conjunction with phytoremediation.