|MadSci Network: Biochemistry|
The only uses for human urine that come to mind are as a component of fertilizer (mostly for the urea nitrogen content). This cannot be done directly on growing crops as it will burn foliage. Instead, urine can be added to composting organic matter to supply nitrogen to the composting organisms which then fix part of the nitogen in forms which are useful in gardening. There may be a small further use as an animal repellent to help prevent deer and other pests from lunching in a garden area. J. McCormick
Try the links in the MadSci Library for more information on Biochemistry.