This field has been left fallow for two years, and the soil is now very fertile.

fallow 是形容词，指"休耕的、闲置的"，描述土地暂时不耕种以恢复肥力的状态。这个词源自古英语，与"未耕作"的概念相关。在农业中，fallow land 指特意不耕种以让土壤恢复养分的地块。