Why can I not drop off large quantities of cut grass?

Grass will get soggy quickly and start to rot, creating an odor issue because we are not able to mix the materials up frequently enough.  Also the best way to handle grass is to use a mulching mower so the grass can be left on the lawn to decompose thereby adding more nutrients and organics to your lawn.  This can save on fertilizer which can mean less phosphorus used that could drain into the watershed.