Wow are you sure it said 4" DEEP? Were they in dry form or after reconstituting in water -- they fluff up Several times in volume.
It sounds as though you are using it in an orchard or at least around trees so maybe that accounts for what seems to me an inordinate amount.
Used straight and clumped on the surface, even in smaller amounts, they will get hot and also will become very stinky. Trust me.
In addition to pulling them away from the base of plants, which you should do with ANY kind of mulch (anything thicker than 2" is mulch), I would recommend adding a layer of dry leaves if you can get hold of them, or possibly straw or wheat/bran, layer on top and mix them together.
I normally rake the alfalfa into the soil then cover with "brown" mulch like straw or shredded bark (in case of woody plants) or make a soil mix with them, or add some in the bottom of a planting hole and work them in. I reconstitute with water first in a bucket or wheelbarrow before using unless it's a perfect drizzly day.