momoese

Sul-Po-Mag. A naturally occurring mineral containing significant quantities of sulfur, potash, and magnesium. Application rate: 20 lbs. per 1000 sq. ft

Greensand is mined from ancient seabeds; it is a dry organic fertilizer. It is useful for its ability to slowly supply to the soil a number of different micronutrients, as well as potassium.

I wouldn't worry about some glass in the soil unless you plan on letting children play in it. Most Bananas like a neutral PH. There are exceptions like Ae Ae that prefer acidic soil. When I prepped my beds I went down about 4 feet with the organic matter. Rule of thumb is generally twice as deep and twice as wide as the container, but I just do the whole bed at the same time instead of just the holes.