Prilled urea forty six% contains 46% of nitrogen (N) in ureic form, simply absorbed with the leaves of plants. Absorption from the root system is slower, because urea in soil is transformed (as a result of enzymatic hydrolysis) into the ammonia form available for plants, after which into nitrate form. https://travialist.com/story10597008/the-basic-principles-of-npk-ferterlizer