Beer is loaded with carbohydrates, something that can help feed the microbes that live in your soil. Keeping these microbes healthy is important, because they convert matter in the soil into elements that plants such as grass feed upon.
Along with a can of beer, combine 1 can of soda, 1/2 cup ammonia, 1/2 cup mouthwash and 1/2 cup dish soap that is not antibacterial. Spray on the lawn after mowing.
This tonic works best on lawns that are in poor condition. Test it on a small area before trying it on your whole yard to see if it conditions improve. Do not use it on your entire lawn before seeing results on a small area.