Properly fertilized lawns absorb nonpoint source pollutants, help to stabilize soil, reduce ambient air temperatures, and promote a healthy ecosystem of its own. Overfertilizing can aggravate pest problems, stimulate excessive growth, and require frequent watering. In addition, when too much fertilizer is used on landscapes, the excess can seep through the ground, past the root zone of the grass, plants, or trees, and move into the community aquifer, thereby polluting the area water source. Excess fertilizer also can be washed off by rainfall or irrigation and runoff directly into surface water or stormwater systems, causing algal blooms, fish kills, and nitrate poisoning.
Have your soil tested each year to determine how much fertilizer you need. Lawns, gardens, and flower beds all have different nutrient requirements and should be tested separately. Contact your county Extension office for information on soil testing. Once you have the results of the test, apply only the amount of fertilizer recommended.