Interesting. Wouldn't cut grass from the mower bag do about the same thing? The exact measurement probably depends on the type of grass, but I found references to: 4-2-1 and 4-0.5-2, mostly nitrogen by at least twice as much. That would have much more to offer plants, and most people have a free supply. Used to augment mulch in a garden bed, the soil web will deposit the decomposed bits to the proper level in the soil, in the proper ways, for the nutrients to be able to be used by plants.
Fertilizers designed for grass are usually extremely high in nitrogen to encourage only foliage. IDK why anyone would want to put only nitrogen on most other plants, especially if they are grown for blooms.
