Why do producers need decomposers?

Decomposers return nutrients to the earth by decomposing organic material (such as deceased animals and organisms). Producers are dependent on the nutrients they gain from the soil to make their own "food". Without decomposers, the soil lacks nutrients.

consumers need the producer to eat and not starve

and decomposers. Decomposers are the garbage men of the animal kingdom; they take all the dead animals and plants