Which nitrogen fertilizer source has the least percentage of nitrogen?

Ammonium sulfate is known to contain about 21% nitrogen by weight. This concentration is lower than the nitrogen content found in urea, which contains approximately 46% nitrogen, and calcium nitrate, which typically has around 15.5% nitrogen. Similarly, diammonium phosphate contains around 18% nitrogen. Thus, among these common nitrogen fertilizer sources, ammonium sulfate has the least amount of nitrogen by percentage. Understanding the nitrogen content is essential for making informed decisions about fertilizer application rates and practices in crop management.