scorched earth means that in war the losing country burns the city to the ground *EDIT- Scorched earth refers to the burning of land so that it is rendered useless. This was primarily used by Stalin...
When the Soviets retreated, they burned all the fields and crops behind them so that the Germans would have no food. This policy devastated the countryside and made the Russian peasants very angry...
I think it is called the scorched earth policy because the enemy's homes and farms gets burned down so everything is on fire and it looks like the earth is burning