Other chickens walk around the bale browsing around the edges of the bale, and eating the alfalfa flakes that get scratched off onto the ground by the upper chickens. Alfalfa is a very nutritious food crop. Alfalfa sends it's roots deep into the soil.
Soil or Waste Stacks. A soil or waste stack (normally just called a stack) is a drainage pipe that passes through at least one story(floor to ceiling) as a drain pipe, this also includes any horizontal offsets. Every soil or waste stack will terminate in a stack vent that leads to outside air or a vent header.
Drain-waste-vent (DWV) pipes carry waste and water out of the house without gurgles or fumes. Never install or replace a DWV pipe without consulting a building inspector. These pipes must be installed according to precise specifications. Drainpipes. The centerpiece of a DWV system is the main stack, usually a pipe 3 or 4 inches in diameter that runs straight up through the roof. A secondary stack, perhaps 2 or 3 inches in diameter, serves a branch of the system.