Grow Abundant Gardens publishes an on-line worksheet called “OrganiCalc” that finds a set of recommended amendments from the results of your Logan Labs Mehlich 3 soil test. The area to be amended can be adjusted to suit your garden size. It’s quick and accurate. They publish the algorithm behind it, too.
Where do the Mineralization Target Values in OrganiCalc come from?
Dr. William Albrecht established the 68% Ca, 12% Mg, about 4% K ratios in the 1950s and others have been improving on them ever since.
You can download an Excel spreadsheet (warning, it’s wide, and quite a scroll to the right) which aided in developing the target values for the Mineralization Worksheet.