Quote - It's a surprisingly difficult material. A few quick tries led to ... failure.

Although one of these is a good start on a hamburger shader.

I think it looks pretty good, but the color is off (to less green). Horse poo is a compound material and needs some fibers of grass or straw in it to look convincing.

Some reference:

http://de.academic.ru/pictures/dewiki/80/Pferdeapfel_01_ies.jpg