The cremation procedures to cremate the dead in Hindu custom is not bury them as it is the case with people in other parts of the world. It is said that the Parsis think that both the cremation process as well as burial are undesirable for the that use may be made of the body built day by day for a number of years, to feed the birds of prey like vultures living on carrion. In one respect the suggestion appears to be worthy of putting into practice. The best method of disposing of one's possession is, of course, that of making it useful to men as well as other's of God's creation. This may be safely done, if the deceased do not happen to leave behind them kith and kin, feeling keenly the irreparable loss of their dearly loved persons.
But almost all people do having loving friends and relatives and somehow they would feel more upset if their loved one's decomposition dead bodies and relatives are exposed to be torn limb by limb and devoured by birds of prey then if they are cremated or buried. Here it is only a question of sentiment and strictly speaking, all of three modes of disposing of the dead give equal amount of sorrow to the surviving relatives.
Anyhow, the best way of disposing of the corpse is said to be by cremation, and the reason for this are, it would prevent decomposing of the corpse which pollutes percolating water reaching wells and endangering human safety by breeding dangerous microbes. The second reason, rites for the dead enjoyed in the Hindu Sastras or rituals for the dead require the cremation of the corpses. Does soul go after death if the corpses are burnt in fire according to Hindu norms? Well, its like this, if the corpses are not burnt, they say that the tenants of these corpses would not reach the super-physical worlds were the rites performed for the dead could benefit them.
Even among the Hindus all do not cremate the corpses. For instance, a sanyasi, if he dies, is buried and not cremated.Children below a particular age are buried and not cremated. Certain lower caste Hindus in India only bury the corpses and do not burn them.
The reason for these is obvious. The souls of men who have reached a particular stage in human evolution should reach a particular stage in human evolution should reach a particular super-physical world after death to make progress, and rites for the dead performed by the relatives lifts them up to those levels. Sanyasis do not need the help of the living to reach such levels since by renunciation of everything worldly, they acquire merit which elevates them to those levels. Very young children do not need cremation if they die, because they have had no time to develop emotions and intellect sufficiently to require the assistance of the rites for the dead performed for them by the living. They simply rise to those levels as soon as they die.
As for the burial of the corpses by the lower caste Hindus and others, it need only be said that certain customs they follow are considered enough to lift them to super-physical regions suitable for them to remain and make progress.