Hazelnut and Expresso coffee grounds in the garden

There were two coffee shops in the neighborhood who were so gracious to save their grounds for me and I picked up a bucket of coffee grounds from each yesterday.    The grounds were sprinkled over the garden and spaded in.  The whole garden had this unusual aroma of hazelnut and expresso and the bird activity really seemed to pick up - possibly the earthworm radar had gone off, they seem to love coffee grounds and must have started to migrate to the freshly spaded soil.  Coffee beans contain protein, about 12%,  which converts into nitrogen.  Using the protein to nitrogen conversion factor of 6.25:1 we can estimate about 2% nitrogen.

Should we try to use the grounds on the lawn?  Using the old rule of thumb of applying a pound of nitrogen for 1000 square feet of lawn, you would need 50 pounds of coffee grounds per 1000 sf. (considering that 100 pounds of coffee grounds X 2% nitrogen would provide 2 pounds of nitrogen in the 100 pounds of coffee grounds).

Now that's quite a bit of coffee grounds, but hey, they're free.