There are numerous organic liquid feeds, but most of them are home-made. They work really well because the nutrients in them are available immediately to the plants.
Manure leachate or "tea".
Herbivore Manure in a bucket of water, which has had time to de-chlorinate.
Left for a few hours, or, better still, stirred every hour, it will still be aerobic, but will have leached some goodness from the manure, and there will be some beneficial bacteria in the water.
Comfrey
Comfrey is a nutrient/trace element "miner" which brings goodness to the surface via its deep roots and has leaves bursting with plant food.
"Chop-and-drop" the leaves where you want to feed, or submerge them in in a bucket of water, with something heavy to weigh them down, whilst they rot down into a foul-smelling, but nutrient-rich brew.
A corner-stone of vegan-gardening.
Two of many organic liquid plant feeds.
I can't think of one which would poison your plants if you over-applied.