If you can get a soil microbiome sample and keep it alive or dormant until you can inoculate it into your substrate that would be optimal for an organic path unles your plantation is in "durian native" soils or similar (dipterocarpace dominated). That sample should ideally come from Borneo, Sumatra or Java if you are talking about Durio Zibethinus.
I am acctually in support of sahai1 on the red dirt but would calssify it as (red clay, sediment and rocks), but I would add that this would be sub soil and not be the constitution of the topsoil which would pretty much be the by products of animals and other plants (living compost in different stages of decay). I make that subsoil recommendation since that is the subsoil found in some areas where they grow naturally but Durio zibethinus can also be found naturally on peat moss swamps in lowland areas (this is not same as flooded clay soil which could suffocate the roots and would probobly not be good for graftade plants or some D . Zib. varieties).
