Super digested compost is called because

Super digested compost is called so because Super phosphate is added to the compost during its preparation.
Super digested Compost is an environmentally natural fertilizer, which is a mixture of decomposed organic matter and is used to improve soil structure and provide nutrients, it acts as a fertilizer and can also be used as a mulch to suppress weeds and retain moisture.
And on the addition of superphosphate fertilizer make it more nutritive and effective to be used.