Been to JAS gombak for other purpose last month,
the officer there told me its common that area around kuala selangor has some industry like 'tanah bakar'.

they make an igloo like soil, put a lot of wood inside, and burn the soil for several month. when its dry/black enough, then they sell it for around ~RM8 per/kg. Its a no cost industry with very high profit.

this type of soil is really good for flower/fruit tree planting