What Is 'Piping'?

What does the term 'Piping' refer to (when used in the context of composting)? When looking up soils in the USDA's Web Soil Survey database, I've occasionally seen this listed as a limitation under the 'Composting Facility - Surface' parameter without any add'l information provided.

My efforts to find explanatory links on the topic have yielded nil.

Found it! Per the NRCS Soil Survey Manual Introduction:

(https://www.nrcs.usda.gov/Internet/FSE_DOCUMENTS/nrcseprd1335011.pdf)

'Tunnel erosion may occur in soils with subsurface horizons or layers that are more subject to entrainment in moving free water than is the surface horizon or layer. The free water enters the soil through ponded infiltration into surface-connected macropores. Desiccation cracks and rodent burrows are examples of macropores that may initiate the process. The soil material entrained in the moving water moves downward within the soil and may move out of the soil completely if there is an outlet. The result is the formation of tunnels (also referred to as pipes) which enlarge and coalesce. The portion of the tunnel near the inlet may enlarge disproportionately to form a funnel-shaped feature often referred to as a "jug." Hence, the term "piping" and "jugging." The phenomenon is favored by the presence of appreciable exchangeable sodium.'


Several other PDFs came up when googling "Soil Survey Manual", there is a lot of information between them...



One can see that this sort of erosion would not be real ideal beneath a nice big compost mountain, providing a handy escape route for all your yummy nutrients... and possibly putting too much something somewhere else!

Greetings D,

"Found it! Per the NRCS Soil Survey Manual Introduction:"

The above pdf seems to be from the era before the county-based soil survey manuscripts were compiled into the Soil Data Mart / made accessible through the Web Soil Survey and Soil Web portals.

This is most illuminating, thank you!