Super digested compost is called because

Super digested compost is called so because Super phosphate is added to the compost during its preparation, thus the prefix Super is added to differentiate it from the normal one.
Compost is a mixture of ingredients used to fertilize and improve the soil, prepared by decomposing plant and food waste and recycling organic waste. And on the addition of superphosphate fertilizer make it more nutritive and effective to be used.