Prilled urea 46% consists of 46% of nitrogen (N) in ureic form, simply absorbed because of the leaves of plants. Absorption through the root system is slower, because urea in soil is converted (as a results of enzymatic hydrolysis) into the ammonia form available for plants, and then into nitrate https://thegreatbookmark.com/story20330259/the-greatest-guide-to-npk-fertilizer-how-to-make