Funding for this research was provided by:
Natural Science Foundation for Young Scientists of Shanxi Province (201801D221323)
the Scientific and Technological Innovation Programs of Higher Education Institutions in Shanxi (201802107)
Received: 3 March 2020
Accepted: 23 August 2020
First Online: 31 August 2020
Ethics approval and consent to participate
: Not applicable. The soil samples used in this study were provided by the Standardized Planting Base of <i>Sophorae</i> of the Zhendong Chinese Herbal Development Company, which does not require ethical approval.
: Not applicable.
: The authors declare that they have no competing interests.