Turf grasses must be properly fertilized to maintain the right colour, thickness, and health. A well-fed grass recovers more quickly from stress and is more aggressive against weeds. As with all living things, proper nutrition is important to prevent diseases and insects. The major nutrients needed for quality lawns are nitrogen, phosphorus, potassium, and iron. All are needed for quality turf, but some are more important than others. Grasses use nitrogen more than any other nutrient.
The goal of any fertilization program is to compensate for nutrient deficiencies in the soil and provide those nutrients that are needed by grass plants to sustain healthy growth and remain competitive against diseases, insects, and weed invasion. Few soils contain enough available nitrogen to maintain healthy turf grass. Nitrogen shortages lead to very slow growth, yellowing of the plants, thinning of turf, weed infestation, and increased incidence of some diseases.
On the other hand, over-fertilizing with nitrogen leads to excessive shoot and leaf growth, reduced root growth, lower plant carbohydrate (food) reserves, increased susceptibility to environmental stresses, and some diseases.