How to apply nitrogen to crops
Soil test said garden needed 34-0-0-0 nitrogen and to wait for crops to be at least 4'' tall. How close and how do I apply nitrogen? Needed 34-000 but was told it is illegal to purchase.
34-0-0 fertilizer is pure ammonium nitrate; it is hard to get because it is potentially explosive. It basically means that your soil needs a lot of nitrogen. I'm afraid I have to question a soil test that would recommend this formulation to a home gardener. I recommend you get another soil test from a different source.
In addition, this article will help you learn more about nitrogen in the soil: https://www.gardeningknowhow.com/garden-how-to/soil-fertilizers/nitrogen-plant-fertilizer.htm
And this article will tell you more about fertilizer in general: https://www.gardeningknowhow.com/garden-how-to/soil-fertilizers/fertilizer-numbers-npk.htm