Effects of plant species identity, diversity and soil fertility on biodegradation of phenanthrene in soil

The work presented in this paper investigated the effects of plant species composition, species diversity and soil fertility on biodegradation of 14C-phenanthrene in soil. The two soils used were of contrasting fertility, taken from long term unfertilised and fertilised grassland, showing differences in total nitrogen content (%N). Plant communities consisted of six different plant species: two grasses, two forbs, and two legume species, and ranged in species richness from 1 to 6. The degradation of 14C-phenanthrene was evaluated by measuring indigenous catabolic activity following the addition of the contaminant to soil using respirometry. Soil fertility was a driving factor in all aspects of 14C-phenanthrene degradation; lag phase, maximum rates and total extents of 14C-phenanthrene mineralisation were higher in improved soils compared to unimproved soils. Plant identity had a significant effect on the lag phase and extents of mineralisation. Soil fertility was the major influence also on abundance of microbial communities.

► Two grassland soils of contrasting fertility showing differences in total nitrogen content (%N) were used in this study.
► The effects of individual plant species and plant diversity on mineralisation of 14C-phenanthrene in soil were investigated.
► Soil fertility was the major influence on mineralisation of 14C-phenanthrene, and abundance of microbial community.
► The presence of a specific plant plays a role in the extent of mineralisation of phenanthrene in soil.