The answer to 'why is my sod yellowing' is that there are several common causes, including improper watering, nutrient deficiencies, disease, or pests. Sod that is not getting enough water will start to turn yellow and dry out. Nutrient deficiencies, especially in nitrogen, can also lead to yellowing leaves. Diseases like fungal infections or pests like grubs can damage the roots and cause the sod to yellow as well.
To fix yellowing sod, first check your watering schedule and make sure the sod is getting 1-2 inches of water per week, either from rainfall or irrigation. Apply a balanced lawn fertilizer to provide the necessary nutrients. If disease or pests are the issue, you may need to treat the lawn with fungicides or insecticides. If the problem persists, it's best to call a professional landscaper to diagnose and address the underlying cause.