I think being buried basically consists of being composted, which is why old burial grounds are so uneven as the graves sink... The original idea of burial I think was to prevent the corpses being dug up and dragged to pieces by scavengers, rather than to preserve the bodies (as in the case of American and Egyptian embalming), but of course oaken coffins and so on can delay the process of decay in extreme cases by hundreds of years.
(When researching "Phantom of the Opera" fan-fiction I came across the interesting phenomenon of the ossuaries in Brittany, where the soil is thin and poor, and the bones of the dead were removed and stacked above ground once the flesh had sufficiently decayed, in order to make more room in the churchyards... https://link.springer.com/chapter/10.1007/978-1-349-25300-5_5 )
Probably the best and quickest means of returning dead humans to a useful function in nature is to let the scavengers take their course. https://www.atlasobscura.com/articles/sky-burial (I note that this again appears to originate in a lack of soil and a reluctance to waste it on interment!)
no subject
(When researching "Phantom of the Opera" fan-fiction I came across the interesting phenomenon of the ossuaries in Brittany, where the soil is thin and poor, and the bones of the dead were removed and stacked above ground once the flesh had sufficiently decayed, in order to make more room in the churchyards... https://link.springer.com/chapter/10.1007/978-1-349-25300-5_5 )
Probably the best and quickest means of returning dead humans to a useful function in nature is to let the scavengers take their course. https://www.atlasobscura.com/articles/sky-burial (I note that this again appears to originate in a lack of soil and a reluctance to waste it on interment!)