"Mykos" by Xtreme gardening is AWESOME for soil growing and I recommend, no urge strongly, that anyone growing in soil use this fabulous mycorrhizae soil inoculant post haste. In my experiments with this product, I was convinced of its usefulness and positive impact by the reduction in feeding frequency of the plants. The mycorrhizae live on the plants roots in a symbiotic relationship and the mycorrhizae achieve nutrient absorption efficiency, which means your plant is able to utilise the nutrients much more easily and thoroughly, leading to lower requirements for supplemental feeding. It really works!
This product can be found in most grow shops and on eBay too. Might be a bit pricey, but you don't need much and in my opinion, worth every cent!
Hope this helps,.............
Organoman.