This is the 4208th most frequent Japanese word.
乾い
"乾い" (kawai) means "dry" in English.
The word '乾いた' here indicates that the plate has become dry, describing the state after moisture has been removed.
お皿が乾いた。
The plate dried.
In this sentence, '乾いた' modifies the voice, meaning it was a dry or unenergetic tone, metaphorically expressing absence of warmth or liveliness.
乾いた声で話した。
Spoke with a dry voice.
Here, '乾いている' describes the land as lacking moisture, giving a direct physical description of its state.