Baking soda neutralizes the ph in the soil and nothing will grow there. I use baking soda in a 6" wide area around all of the edges of my flower beds to keep the grass and weeds from growing into my beds. Just sprinkle it onto the soil so that it covers it lightly. I usually have to do this twice a year - spring and fall.
WHO KNEW? I did this, and I have NO weeds/grass growing in my pavers! 5 pound bags of Baking Soda at Costco for less than $5.00 - then : Sweep Baking Soda into Sidewalk Cracks to Discourage Weeds. Simply pour or sweep a thick layer of baking soda into sidewalk and patio cracks. The baking soda will kill any small weeds that are already there, and prevent new ones from sprouting