In the first ever case of murder in the human race as recorded in the Quran, we are told how Cain the son of Prophet Adam (pbuh) killed his younger brother Abel out of arrogance and jealousy. Then God sent a raven who started to scratch the ground as if show Cain how to bury the body of his brother. We are also told in the Quran that eventually Cain realized that it was indeed a dreadful act he had committed. But worse still, he did not have the knowledge to respectfully dispose the body of his dead brother. And this simple duty was shown to him by an insignificant animal.
In the Islamic tradition the rituals regarding the dead are derived from the Quran and Sunnah (example of the Prophet, pbuh) and deviations in this respect can only be allowed only under some exceptional situations. The rituals regarding the dead include the method of burying our dead. Other such rituals include washing and then clothing of the corpse in a cloth normally called Kafan, and the Salat Janazah (prayer for the deceased).
One may ask why should there be a stress on burial, when the actual purpose is to dispose of the corpse. The answer to this question is that these traditions form a part of the distinguishing symbols of the nations that find their origin in Divine guidance. All those nations that have their basis in Divine revelation, the Jews, the Christians and the Muslims, follow this tradition. It can therefore be termed as an Abrahamic tradition.
In some rare situations deviations from the traditions of burying may be allowed. e.g. people dying due to infectious epidemic diseases. As a principle, however, we may safely say that in all such situations where the burial of the dead is not possible, an alternative method may be used to respectfully dispose of the corpse.
Burying is better for the environment than cremation.
1. Components of human body present in the soil
Elements that are present in the human body are present in lesser or greater quantity in the soil. Hence it is more scientific to bury a dead body, as it easily gets decomposed and mixed in the soil.
2. No Pollution
Cremating (burning) the dead body leads to pollution of the atmosphere which is detrimental to health and harmful for the environment. There is no such pollution caused by burying a dead body.
3. Surrounding land becomes fertile
In traditional societies, to cremate a dead body several trees have to be chopped, which reduces the greenery and harms the environment and the ecology. When dead bodies are buried, besides the trees being saved, the surrounding land becomes fertile and it improves the environment.
In some countries it is expensive to cremate a dead body when tons of wood have to be burned.
5. Same land can be utilized for burying another body
The wood used for cremating a dead body cannot be reutilized for cremating another dead body. The land used for burying a dead body can be reutilized for burying another body after a few years since the human body gets decomposed and mixed in the soil.