1 Introduction Microorganisms (including bacteria, archaea, fungi, and protists) are major drivers of terrestrial carbon cycling, controlling the balance between carbon storage in soil organic matter (see Box 1 for glossary) and CO2 release to the atmosphere (Liang, Schimel, and Jastrow 2017 and references therein). A growing body of indirect evidence suggests that the soil virosphere is an essential component of soil carbon cycling (Emerson et al. 2018; Graham et al. 2024; Lee et al.