Dose of compost is usually calculated in the basis of nitrogen concentration. I am not too sure , which type of compost you are talking about and what dose of nitrogen are you looking at.

But my bigger question is , whether we are now in a position to afford to apply any composted material as a solitary nutrient source...I have my own doubt .

It is necessary to consider that compost mineralises, making nutrients available, only 50% in the first year (30% in the second one and 20% in the third one). In addition, the percentage of mineralization must be recalculated on the basis of the duration of the experiment, if it is lower than 1 year. In my opinion, in a sandy soil with a low available nitrogen content, it may not be the only source of nutrients but it is useful for increasing the soil water content. In clay soils with a good supply of nitrogen, it can represent an excellent soil amendment. For the above considerations, the amount of compost to be administered to the soil can vary from 20 to 60 t ha-1

It is simply impossible to supplement full dose of RDF through compost , gone are those days for any field or horticultural crops.