Pee on Earth Day is a day to promote the use of urine for growing plants and save water used to flush toilets (June 21 in the northern hemisphere, Dec. 21 in the southern hemisphere).

Urine is a great way to feed plants nitrogen and phosphorous.

Anna Edey, author of the book Solviva, claims to have grown 200 onions in just one square yard using only urine for a fertilizer.