Why the kanji for a field has fire in it

On its own, 田 (ta) usually means a rice paddy, a field flooded with water. That character came from Chinese writing.

For dry fields, Japan made a kanji of its own: 畑, hatake. Dictionaries mark it as a kokuji, a kanji made in Japan.

The main dictionary reading: field plus fire means dry farmland, as opposed to a wet paddy.

Another view links the fire to burning land clear for planting. Some writers point to older spellings that kept burned fields and other dry fields apart. Scholars do not all agree, so we label this one ONE THEORY.