This is in response to an old thread, but here's an update.

BTN+ was a product of Bio-Tech Nutrients which made some “wonder fertilizer” claims. 'Replacing present fertility' was one of the claims, but the product was good when used to supplement existing fertility.

The company was sold in late 2011. New ownership requires tests and data to back all claims. The successor product, BTN (without the + sign) is registered in 44 states and continually goes through numerous 3rd party and University trials on alfalfa, corn, soybeans, wheat, turf grasses, vegetables and fruits across the country. The stuff works, and most all growers who trial it end up using it across the board.