Soil fertility referred to the capacity of a soil to support plant fertility.
In 2267, Spock observed that the soil of Gamma Trianguli VI was fertile and suitable for husbandry. (TOS: "The Apple")
In 2269, the USS Enterprise transplanted the Terratin colony to Verdanis, a fertile planet. (TAS: "The Terratin Incident")
In 2371, the Bajoran Provisional Government sought to use soil reclamator to restore the fertility of land in Rakantha Province, formerly one of the most productive agricultural regions of Bajor before its soil poisoned by the Cardassians and rendered unusable for agriculture. (DS9: "Shakaar")