The Sraddha Ritual : Purificatory Rites - Verse 57-58

Purification of the earth (ground) is by sweeping, sprinkling and smearing (with cowdung) . Outside the village the ground (earth) is purified by the wind. Purification (cleansing) of bow and arrows is effected by (brushing) it with clay. Thus the excellent modes of purification have been mentioned.