Temporal variation of soil friedelin and microbial community under different land uses in a long-term agroecosystem

Despite increasing knowledge of soil microbial community dynamics involved in various factors, relatively little is known about plant-derived allelochemicals and their impact on the development of soil microbial community either independently or synergistically with the other factors. Here we examined an allelochemical friedelin and its relation to microbial community in soils from a long-term agroecosystem under different land uses and seasons. Four land uses (paddy field, maize field, barren and fallow) in an eight-year old continuous establishment were selected to conduct the experiments. Soil samples were taken in spring, summer, autumn and winter at different depths. Friedelin was quantified by gas chromatography (GC) and microbial communities were characterized by phospholipid fatty acid (PLFA) analysis. Subsequently, friedelin was found in all soils but its concentration varied with land uses, seasons and soil depths. The largest observed concentrations always occurred in surface soils and winter samples of all four land uses. Compared with tillage fields, barren and fallow contained a greater amount of friedelin. Both soil microbial community and friedelin varied seasonally, and there were positive relationships between friedelin and microbial community. The signature lipid biomarkers of soil bacteria and fungi, and soil microbial community structure were affected under friedelin application. The results suggest that friedelin may be one of the factors involved in microbial community dynamics under different land-use scenarios and seasonal variations, and friedelin-specific influences in the corresponding microbial community composition result in changes in the microbial community structure in soils from a given agroecosystem. (C) 2013 Elsevier Ltd. All rights reserved.