Grasscycling to Reduce Fertilization and Green Waste On Tall Fescue Lawns.

Both homeowners and professional turfgrass managers potentially burden municipal landfills with green waste and waste fertilizer by removing mowing lawn clippings.  Grasscycling, the immediate return of mown grass to the rhizosphere, can reduce both green waste and turfgrass fertilizer needs.

This study investigated: 1) How much of the N contained in grass clippings is actually available to a tall fescue stand; 2)  effect(s) of grasscycling  on microbial activity in the lawn rhizosphere; and 3) the quality/color of  turf under grasscycling.

A tall fescue (Schedonorus phoenix [Scop.] Holub. Syn., Festuca arundinacea Schreb.) research plot was established on the University of California, Davis campus. Two variables were introduced: 1) mowing technique (mulched clippings versus caught and removed clippings); and 2) rate of nitrogen fertilization (48, 96, and 192 kg N ha^-1 y^-1).  Based on clipping yield data collected, we estimated 33, 48 and 87 kg N ha^-1 y^-1 were removed from plots receiving 48, 96, and 192 kg N ha^-1 y^-1, respectively. There was no significant difference in clipping yields throughout the year between the two mowing treatments.  NDVI (Normalized Difference Vegetation Index) dropped below the acceptable level (0.6) during the winter and late-summer months for the 48 and 96 kg N ha^-1 y^-1rates. The 192 kg N ha^-1 y^-1 rate never dropped below the 0.6 threshold. Soil Electrical Conductivity increased with increasing fertilizer rates. None of the other soil characteristic measured (e.g. organic matter, total N, total C, NO^3- or NH⁴⁺) was affected by either the fertilizer or mowing treatments.  When tall fescue was growing rapidly, very little, if any, nitrogen moved past the root-zone.  Total nitrogen in leaf tissue increased as fertilizer rate increased during the summer months. Mowing technique did not affect total nitrogen in leaf tissue.