Long story short: I've been trying to work out why there are shards of china pottery all across the fields of one of the local Big House estates near Maynooth, Co. Kildare, Ireland.
Some considerable digging has found one reference to a practice called 'dock dung', where all the sweepings of a Victorian street were gathered up, carted or even shipped out, and applied to fields as fertiliser. The only bits of Victorian street debris that will have survived for over a hundred years are pottery shards, or so the theory goes.
The one reference is in an essay about the Tamar Valley Orchards in Ian D. Rotherham's Orchards and Groves: Their History, Ecology, Culture and Archaeology, and it's basically a casual remark. I can't find anything else that doesn't come from that reference, so if this was a real agricultural practice, it may have had another name.
I'm looking for other evidence of the practice (or, I suppose, other reasons there might be shards of pottery all across the fields), or other names for the practice.
Arthur Young mentions it back in 1797 - are you looking for Victorian only examples?
Pottery shards are common in soils anthropogenically enhanced, often called Terra Preta in south america .
You can find reference to the practice you speak of being used in asian countries though not referred to as dock dung, in the book "Farmers of forty centuries".
There was actually an entire profession who went around sweeping to collect the detritus and dust from peoples homes to be used as fertilizer in some asian countries. Tests show it is high in nitrogen.
Pellets made of pottery clay are used as a growing medium in modern day hydroponics because of their ability to hold moisture and nutrients to be slowly released to the plants.