Your own lawn is the most natural and economical fertilizer available on the market today. Consider that every individual plant of Kentucky bluegrass produces about 3 feet of growth a year. The average lawn produces about 233 pounds of clippings every year for every 1,000 square feet of turf area. Leaving these clippings on the lawn and allowing them to decay and decompose in place is the equivalent of three applications of lawn fertilizer.

This process also builds up humus, keeps soils microbiologically active and, over time, improves soils physically and chemically. Grass is the most effective plant available for reconditioning the soil.  An extremely important function of turfgrasses is soil improvement through organic matter additions derived from the turnover of roots and other plant tissues that are synthesized in part from atmospheric CO2 via photosynthesis. A high proportion of the world's most fertile soils have been developed under a vegetative cover of grass (Gould, 1968*)

Gould, F.W. 1968. Grass Systematics. McGraw-Hill, New York.