Wikipedia
In Roman mythology, Sterquilinus ("manure"; also Stercutus or Sterculius) was a god of fertilization. He may have been equivalent to Picumnus. The Larousse Encyclopaedia of Mythology gives the name as Stercutius, a pseudonym of Saturn, under which the latter used to supervise the manuring of the fields.
The name Sterquilinus comes from the Latin "stercus" meaning "fetilizer" or "manure". His name was altered to avoid confusion.
Early Romans were an agrarian civilization and, functionally, most of their original pantheon of gods — as against the later ones they adapted to Greek stereotypes — were of a rural nature with figures such as Pomona, Ceres, Flora, Dea Dia; so it was only apt for them to have a god supervising the basics of organic fertilization. Sterquilinus essentially taught the use of manure in agricultural processes. He was not the sole deity of manure on its own; as in, sewage.