I'm actually using this in my yard right now and it works. A bit slower than Roundup but much better for the environment. Kills weeds in about 48 hours. I don't use Dawn instead we use Seventh Generation dish soap.
(Saw this on PBS years ago) Secret Lawn Tonic Recipe From Golf Course Groundskeeper - Updated .. You will need: One full can of regular pop (any kind-no diet soda) .. One full can of beer (no light beer) 12oz .. 1/2 Cup of Liquid dishwashing soap (do NOT use anti-bacterial dishwashing liquid).. 1/2 Cup of household ammonia .. 1/2 Cup of mouthwash (any brand)