Prilled urea 46% consists of 46% of nitrogen (N) in ureic form, very easily absorbed by the leaves of plants. Absorption in the root system is slower, because urea in soil is transformed (like a results of enzymatic hydrolysis) into the ammonia form available for plants, then into nitrate form. https://mysocialguides.com/story5751385/indicators-on-urea-fertilizer-nitrogen-you-should-know