Wall Earth (Bì Shàng Tǔ)

Bì shàng tǔ is a type of Earth-attribute combination in the Sixty Jiazi Nayin, corresponding to the two stems and branches Gengzi and Xinchou. The name is derived from imagery of earth or lime plastered on walls. Traditionally, it is considered processed earth, used for partitioning and protection, distinct from natural mountain soil or farmland. In old almanacs, when analyzing a person's life year or day pillar, if Gengzi or Xinchou were encountered, this Nayin was used to infer its Five Elements attribute. In folk customs for date selection or metaphysical reference, this classification is often used as an auxiliary method to judge relationships of production and overcoming between things or to choose an opportune time.