The first scorched earth policy came from ancient times when conquering armies would plow salt into the earth of a conquered city to prevent the city's former inhabitants from returning. The high sodium content of soil that has been plowed with salt makes it difficult for vegetation to grow. Today, salt is an easy-to-find ingredient for homemade weed and grass killer. Salt is a drying agent in homemade weed killer. Using it on grass and weeds will dry plants.
Place a saucepan on a stove and fill it with 1 gallon pickling vinegar. Bring the vinegar to a boil.
Slowly stir in 1 cup salt. Stir until the salt dissolves.
Add 1 tbsp. of liquid dish soap into the boiling vinegar. Dish soap acts as an adherent to make the herbicide stick to the plants.
Take the saucepan off of the burner and allow it to cool. Place a funnel into the open neck of a spray bottle.
Pour the vinegar into the spray bottle. Place the spray lid onto the bottle.
Point the bottle's spray nozzle at grass or weeds that you wish to kill. Spray the liquid until the plants are saturated. The plants will wither and die.