Potassium Nitrate best fertilizer for tomatoes
I just finished foliar feeding all the plants in my garden with a dilute solution of potassium nitrate. I mix it up in a 30 gallon barrel and use a watering can to apply it.
This article documents tests done using potassium nitrate for foliar feeding or preplant fertilization of tomato plants in several countries. Some of the things noted were 25% increase in yield, higher percentage of marketable fruit, increased disease and insect resistance, increased lycopene, and it can even be used to speed up germination of seeds. The proportions of K and N are exactly what the plant needs. Last time I bought some it cost about 53 cents a pound in a 50 pound bag.
Here is a link that might be useful: potassium nitrate fertilizer for tomatoes