Good morning coldandwindy, you can make liquid feeds out of oooodles of stuff. I make seaweed liquor by hanging a bag of seaweed in a waterbutt, I've also made comfley tea from the hedgerows (but there's a bit of a cerfuffle over 'Bocking 14' people seem to think any others are substandard).
I've also made liquid feed from well rotteh horse manure but I've never kept records as the the relative effectiveness of once agains another.
Cheers, Tony.