Monitoring of the content of heavy metals in the main types of soils and plant feeds of the republic of Mari ElSergey Smolentsev, Ekaterina Dubnikova, Tatyana Nikolaeva, Nadezhda Kislitsyna, Maria Bukatina, Maria Ershova, Vasiliy Polikarpov, Darya Elmakova, Larisa Chernyshova and Olesya SavchenkoBIO Web Conf., 141 (2024) 02001DOI: https://doi.org/10.1051/bioconf/202414102001