Homeowners can diagnose chemical-based problems by checking the color of the grass. Yellow grass, for example, might indicate that the grass needs fertilizer or other nutrients. Spots on the grass can indicate a range of diseases, included blight and fungal infections.
Grass needs a number of chemicals to grow safely. Nitrogen, in particular, is essential for ensuring healthy growth; yellow grass or thin leaves might indicated a nitrogen deficiency, which nitrogen-based fertilizer can often correct. Iron deficiency can cause similar problems as well, and applying an iron supplement can sometimes result in greener grass in a matter of hours. Salt can cause damage to grass, especially in areas where municipalities use salt to melt ice on the road. Homeowners can often diagnose salt damage by noting its proximity to a salted road in winter months.
Lawnmowers can cause a range of problems as well. Grass needs to be a certain length to collect enough sunlight to grow properly, and stunted grass might indicate that the blades are set too low. Gasoline-powered lawnmower sometimes leak gasoline and oil, which can cause localized and widespread problems. A weak mower blade can cause the grass to turn brown or gray by splitting or tearing the grass instead of cutting it cleanly.