Variation in soil characteristics of ex-coal mining areas in Sawahlunto, West Sumatra Welly Herman, Iskandar, Sri Wilarso Budi, Heru Bagus Pulunggono, Andri Syaputra and Kurniati BIO Web Conf., 99 (2024) 05010 Published online: 01 April 2024 DOI: 10.1051/bioconf/20249905010