The roots of this pernisceous weed do go down deep. It may take several years for you to eradicate it totally, but keep cutting new growth down as soon as you spot it. It needs light to grow. I know it can it can be steeped in water to make a fertiliser. But not having the problem I know little about the plants properties. I have in the past worked to remove it from between paving on a customers garden. I crushed the leaves underfoot and sprayed it with round up. It did weaken the plant considerably. and I always cut down any new growth as soon as I spotted it.

will try it thank you

Very difficult indeed to eradicate altogether - just keep removing it as soon as it appears. It will weaken eventually if it never gets a chance to photosynthesize. Be especially careful to remove any of the different stems that have no little leaves but have a knob at the top - these are the spore bearing stems, so you need to prevent them spreading that way at least! If glyphosate doesn't work you could try deep root weedkiller on the paving as long as it s kept away from other plants.

It had all sorts of medicinal uses in days gone by, including the ashes for stomach acidity, and I believe it was also used as a pan scourer.