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.
The start of a toilet waste system is the toilet's own waste outlet, while the main pipe is the soil stack. The stack is a 3-inch or 4-inch length of vertical pipe that drops to the sewer and is connected to a 2-inch pipe that rises through the roof to provide venting.