Grass on your lawn is like any other plant in that there are times when it is growing and needs more nutrients and times when it does not. The leaves, and more importantly the roots, will be burned if fertilizer is heavily applied any time other than late spring and early summer. Lawns of any type require more nitrogen than they do phosphorous or potassium, meaning homemade fertilizers must be designed to accommodate this.
A good recipe for fertilizer involves mixing one can of beer, one cup of ammonia, one cup of molasses and one cup of liquid dish soap. It should be diluted in a 10:1 ratio with water and sprayed across the lawn no more than once a month. The dish soap helps break the surface tension of the water on the grass so that the fertilizer can penetrate more deeply. At the same time, the beer and molasses promote microbial reproduction, which breaks down the ammonia into nitrates for the grass.
Tea fertilizer doesn't actually use tea, but rather involves placing several quarts of manure into a burlap sack and then steeping it in the sun for a few days in 5 gallons of water. The resultant mixture of liquid seeping from the sack is highly concentrated nitrates and tea-colored. Each cup of concentrated tea fertilizer should be diluted in a gallon of water before being sprayed across the lawn.
Dilute one 12 oz. can of tomato juice in two cups of water. Mix in two-thirds of a cup of orange juice and a half cup of liquid fabric softener before spraying on the lawn. This is a particularly strong fertilizer and should only be used once every two months at most. The chemistry of it is this: Liquid fabric softener is primarily quaternary ammonium salts, which are highly alkaline when chemically stable. This would cause severe burns to any plant under normal conditions, but tomato and orange juice are both very acidic. The acid neutralizes the alkaline qualities of the fabric softener, breaking down the ammonium salts into its component parts, which are primarily nitrates. This combined with the nutrients from the fruit juices makes for an excellent fertilizer.