We Add Nitrogen to the Soil to Enhance Plant Growth

We add nitrogen to the soil to enhance plant growth and increase our food supply. What is the downside of this?

A) Nothing. We need the food and the nitrogen enhances production.
B) It's a waste of money because the added nitrogen doesn't make much difference in plant production.
C) It's a waste of money because the soil bacteria supply all the nitrogen the plants can possibly use.
D) It does increase plant production, but the excess ends up in our water, promoting algae growth and making the water undrinkable and, at times, unlivable for fish.
E) Nothing because the excess nitrogen just evaporates into the atmosphere as part of the nitrogen cycle.