It's nitrogen in the urine that plants respond to.

Don't use Epsom salts too often, it will build up in the soil and work against you. But it does make the tomatoes happy to use 2 or 3 times during the growing season. The mix is pretty dilute, just a couple of tablespoons per gallon of water.

Foliar feeding is good, when done early. Don't spray the leaves in heat or bright sunshine or you'll burn them with the water in the sun on the hot leaves. And don't rely just on foliar feeding; my gardening guru here in the states was talking about that just this week on his radio show - the roots get "lazy" and won't interact with the soil and microorganisms as easily if you only do foliar feeding. Dribble some of that liquid directly onto the soil as weel.

Are you a regular gardener, Dick, or is this something you've just discovered?