The object of research is corrosion of metal and polymer materials in soil operating. Method. Experimental studies of soil corrosion of samples made from metal piping materials of different manufacturers, as well as polymer composite materials based on an epoxy binder in soil conditions of the Republic of Mordovia (Russia). Metal samples were exposed to various types of soils (chernozem and loam) at a depth of 410 mm and 630 mm. Polymeric materials were located in various soils at a depth of 0.5 m and 1.5 m. During the tests, the samples were kept under conditions of variable temperature and humidity for 12 months. Microbiological studies were carried out to identify microorganisms on the surface of the samples. Results. The species composition of microorganisms that settled on the samples during the tests was established, and changes in the mass-strength properties of the composites were revealed. Methods for protecting pipeline materials from biological damage are proposed.