Yellow Lawn

Yellowing is often a sign of a condition known as chlorosis. Iron is a necessary nutrient used by the plant in the formation of chlorophyll, which of course is needed for photosynthesis in plants. Certain soil conditions, such as improper soil pH and/or the presence of high phosphate levels, can cause elemental iron to be locked up in compounds the plant cannot take up and use. Since the plant can´t get the iron it needs, it can´t form chlorophyll and photosynthesize properly, resulting in the yellowed appearance. This can be corrected in some cases by applying chelated iron to the soil. It may also be corrected by applying elemental sulfur, which will reduce soil pH and release iron.