using mulch in an outdoor grow?

I heard a good way to use mulch is using hay?

directions:
over your topsoil put a layer of hay then a layer of compost then another layer of hay..does this sound good

I think that is a good idea, its alot better than leaving the soil bare. It gives the soil alot more moisture, and that also collects worms to, hence makes the plant grow bigger which makes more buds lol.