Impact Of Natural and Synthesized Hormones On Soil Microbial Community Structure In Manure-Amended Soils With and Without Biochar Treatment.

Hormones are of an environmental concern due to their capacity to induce strong endocrine responses in different species. Application of animal wastes to agricultural lands leads to the release of hormones and pharmaceuticals into the soil environment. Biochar as a soil amendment has been proposed for enhancing carbon sequestration and contaminant remediation. However little is known about the ecological risk of hormones in the soil environment. In this study, we investigate the influence of selected hormones on microbial community structure in two soils with and without biochar treatment. Two soils with different organic matter contents were amended with manure-spiked with natural hormone 17β-estradiol (E2β) and synthesized hormone 17α-ethinylestradiol (EE2) and incubated for one week. The effects of hormones on soil microbial community were studied by analysis of phospholipid fatty acids (PLFA). Different biomarker ratios including fungal:bacterial PLFAs (FBR) and cyclopropane: monoenoic PLFAs (CMR) for stress evaluation were calculated. In general, the high organic soil with high organic matter showed a greater increase in total microbial biomass than the low organic soil, and biochar-treated soils had greater response to hormones, especially the synthetic one. Overall the results suggest that biochar changes soil microbial sensitivity responding to hormones.