Martian soil
From Tardis Wiki, the free Doctor Who reference
Martian soil could be obtained from the surface of Mars. It was slightly alkaline and contained vital nutrients such as magnesium, sodium, potassium and chloride.
Mia and Peter Bennett used samples of Martian soil to grow plants such as asparagus, green beans and turnips. Chemicals had to be added to soil in order for the produce to overcome the harsh environment of Mars. (TV: The Waters of Mars)
