If you have a large enough amount of soil you may be able to start a compost, add spent soil to compost, stir and reuse. A large enough pile would allow it to become perpetual id imagine.Nice, I'm just starting to try and reuse soil... er, more like save up soil to reamend and then reuse. I've got awhile before I'll be at that point, though.
Equisetum is just the Latin term for Horsetail. I've been spraying it as a preventative measure. Working great so far, and the plants love the Silica from it, too. Nugs made a tutorial on it I believe, although he uses powder instead of the shredded product (which I prefer over the powder).