Potash is created from ash or lye at an ashery by a dwarf with the potash making labor enabled. Potash can be used to fertilize a farm plot, to increase stack size of harvested plants, or be refined into pearlash. Potash in real life
Potash comes in bars, stored in a bar stockpile and viewable in the stocks screen under "bars".
[MATERIAL:POTASH] - reconstructed from data extracted from memory [STATE_COLOR:ALL:WHITE] [STATE_NAME_ADJ:ALL_SOLID:potash] [STATE_NAME_ADJ:SOLID_PASTE:potash slush] [STATE_NAME_ADJ:SOLID_PRESSED:pressed potash] [BASIC_COLOR:7:1] [BUILD_COLOR:7:0:1] [TILE_COLOR:7:7:1] [MATERIAL_VALUE:3] [SPEC_HEAT:800] [SOLID_DENSITY:1200]