Although it’s certainly not necessary, your worms will be more productive (& I presume happier & healthier), if you sprinkle this Sand-Soil mix onto your scraps when you bury them in the bin.   Mix thoroughly, at least several gallons, equal parts:

• Sand
• Garden Soil
• Oyster Shell flour
• Rock Dust

Sand provides grit which assists the worms’ digestive process.  The soil provides microbes that will speed decomposition.  Oyster Shell Flour provides calcium and aids microbial growth.  If you can’t find it locally you can purchase it thru this link.  Rock dust provides minerals and aids microbial growth also.  For more on rock dust see A Rock Dust Primer.

While the main purpose of  this mixture is to help create an optimum envrionment for the worms,  it will also improve the quality of the castings, and thus your garden/potting soil.