Ever since ancient times, the sowing of salt has been synonymous with severe and deadly retribution. The Roman general Scipio Africanus the Younger was said to have ended the Third Punic War in 146BC by razing Carthage, enslaving its population and spreading salt on its fields. In the biblical book of Judges (9:45), the brutal and unprincipled King Abimelech laid siege to the Canaanite city of Shechem. ‘He took the city,’ the biblical story says, ‘and slew the people that was therein, and beat down the city, and sowed it with salt.’
Salt kills most plants. In fact, it attacks them in much the same way that carbon monoxide kills humans. In cases of carbon monoxide poisoning, CO molecules exhaust the carrying capacity of your red blood cells, depriving your body of the oxygen it needs. Likewise, most terrestrial plants soak up the sodium ions and sodium chloride from salt much faster than they can absorb essential nutrients such as potassium, calcium and magnesium. Without those nutrients, they perish. Spread salt on the fields of your enemies and their crops will fail.
Read the Aeon story by Mark Anderson - “Enter halophytes”