Another very important issue would be to have minimum dataset of soil properties defining the success of a given crop in order to develop soil quality standards...
As far as I know, there is no ICAR standard for determining soil quality. It is calculated solely on the basis of the parameters measured to obtain minimum dataset. There are many literature available which indicate on how to determine SQI. Please, read them carefully.
As pointed out, there currently are no international standards for soil quality or health, but the Soil Health Institute is working toward quantification of soil health. See the link below for one of their publications: