Sellers of pre-packaged fertilizer would rather you didn’t know but human urine has been used since ancient times as a plant fertilizer. It contains loads of nitrogen, phosphorus and potassium, which is good for plants. Best of all, it’s free. Make sure to dilute it with at least 10 parts water to 1 part urine, or risk burning the roots of some plants. A report published in the Journal of Agricultural and Food Chemistry found that using human urine as fertilizer didn’t change the nutritional content or the flavor of cabbages on which it was used.
Human Urine As A Safe, Inexpensive Fertilizer For Food Crops [Science Daily]