The DMR Hindi folder mixes three quarters loam soil with one quarter sand by volume, then adds chalk powder at 10 percent of the mixture weight. The 2011 manual prefers soil 75 percent plus sand 25 percent, and accepts coir pith with soil or farmyard manure with soil.
The chalk is not decoration. DMR sets milky casing pH at 7.8 to 7.9, adjusted with chalk. That is more alkaline than the 7.0 to 7.5 the same institute sets for button casing, so soil from the button shed is the wrong soil here.