Urea is 46% nitrogen, so its analysis is 46-0-0. This actually has carbon in it, so in a sense, you could call it an organic nitrogen. Not that it's approved for organic use, but it does have carbons in with the nitrogen so carbon is part of the molecule of urea. Urea is a high analysis dry nitrogen. It has a tendency to dehydrate the soil, so it has to be used where there is adequate water. In the right place it can be very useful. One of the uses it's really good for is in corn when the equipment requires a dry application of nitrogen. Urea is a dry granular, so it can spread with a fertilizer spreader just fine. It mixes pretty well with phosphorus and potassium products. You do have to be careful mixing it into limestone. Pelletized limestone and urea would not stay in very well together.