Prilled urea 46% involves 46% of nitrogen (N) in ureic form, simply absorbed because of the leaves of plants. Absorption through the foundation 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://bookmarkangaroo.com/story21644772/is-npk-fertilizer-good-for-cabbage-no-further-a-mystery