Nitrogen is a key element in maintaining a healthy lawn with few insect and disease problems. Clover stays green because it obtains nitrogen from the air, but grasses cannot. It is best to maintain a level of nitrogen in the soil that: (1) does not stimulate excessive leaf growth, which reduces mowing frequency; (2) doesn't encourage shoot growth at the expense of root growth; and (3) varies according to the cultural and environmental conditions present. Because heavy rains and watering leach nitrogen from the soil, periodic feedings are necessary throughout the growing season. Acidic soil may cause nitrogen to be unavailable to the grass.
Apply a lawn fertilizer according to the instructions on the label. Adequately fertilized lawns will exhibit acceptable density and color without excessive growth. To prevent burning and to move the nutrients into the soil, water thoroughly after application. Grass begins using the nitrogen in the fertilizer within 15 to 24 hours. For the most efficient utilization of applied nitrogen, leave grass clippings on the lawn if they are not extremely long. (For more information on fertilizing, see Fertilizing.) If the soil is acid (below pH 5.5), liming is necessary for effective nitrogen utilization. (For more information on pH and liming, see pH.)
