What Causes Fairy Rings on Lawns?
Mushrooms, the fruiting bodies of fungi that poke their heads up out of the soil after rainstorms, tell only part of the fungi’s story. Hidden in the soil is a huge network of threadlike mycelia. Mushrooms are not individual organisms. Rather, they are just one part of the mycelia lurking beneath your lawn. Fungi start out as single spores. As each spore grows, the strands of mycelia radiate out from it, forming a circle. Each year, the circle expands. Within the circle, there are usually several regions. As fungi feed, they break down organic matter, releasing nitrogen into the soil. This nitrogen dump creates the darker rings in lawns. Brown rings are caused by heavy mycelia growth. The mycelia hog all of the moisture in the soil, keeping your lawn from getting the water it needs. They can form a dense, impermeable layer in the soil that is very difficult to combat.
