Enhanced Cd-Zn-Pb-contaminated soil phytoextraction by Sedum alfredii and the rhizosphere bacterial community structure and function by applying organic amendments

Abstract

The phytoextraction efficiency of metal contaminated soil needs to be improved. Organic amendment can be used to enhance the effectiveness of phytoextraction. However, studies on how organic amendment influence the rhizosphere microbial community of hyperaccumulators are still scarce. Two kinds of spent mushroom substrates (H and T) and their biochars (HB and TB) were used to facilitate the phytoextraction by Sedum alfredii Hance. The phytoextraction efficiency was monitored by measuring Cd, Zn and Pb extraction and the subsequent changes of soil microbial biomass, activity and diversity (indicators of soil health and functioning) . Compared to the control, the H and T amendments increased S. alfredii Cd uptake by 92% and 73%, and Zn by 106% and 67%, respectively. Organic amendments increased the microbial biomass and activities and substantially changed bacterial composition and diversity of rhizosphere soil. The relative abundances of some rhizosphere beneficial genera such as Promicromonospora, Acidibacter, Roseiflexus, Microbispora, Kribbella and Streptomyces were significantly increased under the H and T treatments. Spent mushroom substrates enhanced metal extraction of S. alfredii and improved soil health by increasing microbial biomass, activity and changing microbial community composition thus providing an effective option to facilitate phytoextraction of metal contaminated soil.