Toka sune dasasshen ragowar gobara . Musamman, ash yana nufin duk maras ruwa-ruwa, maras gaseous sharan cewa zama bayan da wani abu konewa . A hikimar tantance sunadarai, don nazarin ma'adinai da karfe abun ciki na sinadaran da samfurori, ash ne maras gaseous, maras ruwa saura bayan cikakken konewa. Toka kamar yadda karshen samfurin na bai cika konewa su ne mafi yawa ma'adinai, amma yawanci har yanzu dauke da wani adadin combustible kwayoyin ko wasu oxidizable sharan. Mafi sanannun nau'in toka shine toka na itace, azaman kayan ƙone itace a cikin wuta, murhu, da dai sauransu. Da duhun itacen toka, mafi girman abin da ya rage na gawayi daga ƙonewar da bai cika ba. Toka iri-iri ne. Wasu toka suna ƙunshe da mahaɗan ƙasa waɗanda suke sa ƙasa ta yi ni'ima. Wasu da sinadaran mahadi da cewa zai iya zama mai guba amma na iya karya up a gona daga sunadarai canje-canje da kuma kananan kwayoyin aiki. Kamar sabulu, toka shima wakili ne na kashe kwayoyin cuta (alkaline ). Hukumar Lafiya ta Duniya ta ba da shawarar toka ko yashi a matsayin madadin lokacin da ba a samu sabulu ba.