Plants require a certain set of nutrients to grow healthy, strong and green. When denied these nutrients, plants wither, become susceptible to disease and even die. Lawns are heavy nutrient users requiring regular fertilization to stay healthy. Fertilizers are graded according to their nutrient content by weight. Complete fertilizers such as 16--4--8, 12--4--8, 10--10--10 and 6--6--6 are recommended for lawn fertilization, according to the Clemson Cooperative Extension.
Test your soil using a pH and nutrient test to determine the lawn's acidity and nutrient content. Soil tests come with instructions, but as a general rule the test requires several samples of soil be taken and distilled in water. Pour the soil water into the soil test container and add the chemical provided. Compare the color of the water with the pH test chart. Add nutrients to the soil as recommended by the test. Soil high in phosphorous and low in potassium requires a fertilizer with a grade of 21-0-0 or 46-0-0, while a soil high in potassium and low in phosphorous will need a fertilizer such as 20-5-10 or 23-0-6, says the University of Minnesota.
Mow your lawn using a mulching lawnmower to return grass clippings to the lawn. Grass clippings are a good source of nitrogen and break down easily as they are composed mainly of water. Leaving clippings on the lawn will reduce the amount of annual fertilizer needed in the lawn by 1 lb. of nitrogen per 1,000 square feet, reports the University of Minnesota.
Apply 1 lb. of nitrogen to the lawn per 1,000 square feet, recommends the University of Minnesota. High-maintenance turf grass varieties require 3 to 4 pounds of nitrogen a year in three or four applications of quick-release throughout the season, applied at 8- to 10-week intervals, says the Ohio State University Extension.
Apply the fertilizer using a spreading device, moving north and south along the lawn. Overlap your previous pass with the spreader by spraying the fertilizer along the tire track made on the previous pass.
Water the lawn after a fertilizer application to activate the fertilizer and move it into the soil. Spray a light amount of water to avoid fertilizer runoff.