Allotments 4 All

Can I make this by using the enormous pile of couch grass roots I have?

Good question,well presented........I dont have a clue :-\

However,you could dry them out and then burn them using the leftover ash in the garden.

Yes you can chuck them in a woven bag then immerse in a bucket/tank of water for a few weeks. Give the bag a prod/squeeze now and then. Nettles are also good for this. Stinks! But good fertilizer.
Alternatively you can dry in the sun until brittle, then crumble into the compost heap...  :)

hiya, romanybob, welcome to the site  ;D
TEY, we put docks, nettles and dandelions in water so can't see a problem with drowning couch  ;D

I chuck all my kitchen and garden compost in a water butt and pour a couple of gallons of water in now and again. As romanybob says it honks something chronic, but I recon it does as much good as comfrey juice  :D

Edited to say:
BTW, Hi everyone  ;D

hiya, uncle Phil, nice to meet you  ;D