Dear Gardener,

The first step is to obtain a soil test to determine 1. if there is a nutrient deficiency, and 2. what kind, and how much is needed. Using fertilizers of any kind when they are not required by plants can damage your lawn and may contaminate creeks and rivers as the excess runs off the soil.

Your question would be properly stated as: what does my lawn need, and how much? 

If the soil test indicates nitrogen is needed, you must then ask 1. how much urea? 2. how much water? and 3. what area (square footage ) can be treated with those amounts?

Here is a good article regarding the use of fertilzers for lawns:http://blogs.cornell.edu/horticulture/files/2011/11/How-Best-To-Fertilize-Your-Lawn-111312-13n9osb.pdf