red clay; red earth; laterite
Refers to reddish soil or clay, often iron-rich. Laterite is a specific tropical soil type.
The red clay in this region is suitable for pottery.
After rain, the red earth road gets muddy easily.
dark-red paint
A dark-red pigment or paint, historically made from red earth. Less common than the soil meaning.
Dark-red paint made from red earth was used on the pillars of the old shrine.
Compound of 赤 (red) and 土 (earth, soil). The reading あかつち is a straightforward kun'yomi combination.