Changes

When a [[Single Pit ]] (S.2) or a [[Single Ventilated Improved Pit|Single VIP ]] (S.3) is full and cannot be emptied, “fill and cover”, i.e., filling the remainder of the pit and covering it is an option, albeit one with limited benefits to the environment and the user. The Arborloo is a shallow pit on which a tree can be planted after it is full, while the superstructure, ring beam and slab are moved to a new pit. Before the Arborloo is used, a layer of leaves is put on the bottom of the empty pit. A cup of soil, ash or a mixture of the two should be dumped into the pit to cover excreta after each defecation. If they are available, leaves can also occasionally be added to improve the porosity and air content of the pile. When the pit is full (usually every 6 to 12 months), the top 15 cm is filled with soil and a tree is planted. Banana, papaya and guava trees (among many) have all proven to be successful.