Man, I gotta say - I've had nothing but problems with re-using my soil, and my grows are mostly organic. I use molasses and AN Iguana Juice grow/bloom, and I've noticed that if I reuse the soil - even if I mixed it in with fresh soil - I get much lower yields and found that it's alot harder to keep the soil pH stable, giving problems like early yellow leaves and stunted growth etc... so I can't recommend it unfortunately. The soil I use is not real soil - it's the Premier HP Pro-mix soil-less stuff. Sometimes I mix in some worm-castings and a tad bit of my home-made compost but nothing fancy...but since I stopped reusing my soil, things have looked a lot greener and happier...just my 2 c. =)