In this whitepaper, we explore the phenomenon of Black Layer in turfgrass—an often invisible but highly damaging condition caused by anaerobic soil processes. Common on high-stress football pitches, Black Layer results from compaction, poor drainage, and excessive irrigation, leading to disrupted water flow, toxic gas buildup, and root damage. We break down the biological and chemical processes behind its formation and explain how to anticipate its development through key indicators such as low oxygen levels, high sulfate content, redox potential, and soil compaction.