Thread: What happens to the deceased?
During the great Plague I'm sure they cremated the bodies, that's what most nations do during plagues. After the battle of Helms Deep I don't think they burned the bodies.
From The Two Towers Chapter 8: The Road To Isengard
But the others, all that were not hurt or wounded, began a great labour; for many had fallen in the battle and lay dead upon the field or in the Deep...In the midst of the field before the Hornburg two mounds were raised, and beneath them were laid all the Riders of the Mark who fell in the defense, those of the East Dales upon one side, and those of Westfold upon the other. But the men of Dunland were set apart in a mound below the Dike.
So clearly the men of Rohan buried their dead.
After the Battle of Pelenor, perhaps it was a bit different.
From the Return of the King Chapter 8: the Houses of Healing
Fire and smoke and stench was in the air; for many engines had been burned or cast into the fire-pits, and many of the slain also...
This is, I think, referring only to the orcs and wild men, and not to the men of Gondor or Rohan. However I could not find anything else in RotK, So I don't know. Perhaps something from HOME would shed some more light on this?