Advantages of Urea Based Natural Fertilizer (Human Urine)One advantage in using urine, as a fertilizer is that much of the urine is available in ideal chemical forms: nitrogen is in the form of urea (ammonia/ammonium which is present at concentrations of approximately 3.5 g/l), phosphorus as super phosphate and potassium as an ion. Urine is almost free from heavy metals - for example, cadmium - because even if we ingest them, they will tend to bind to the liver and kidneys, making the urine much lower in such contaminants than commercial fertilizers.  Human urine is made up of Carbon 11-17% Nitrogen 15-19% Calcium 4-6% Potassium 3-5% Phosphorus 2-5%. Urea outside the body quickly becomes ammonia and will be oxidized by special bacteria (called trifiers) into nitrates. All these 'reactive' nitrogen sources can be used to form amino groups for new amino acids, ultimately being made into proteins. So make other steps to encourage the soil life in your garden and field, e.g. things like mulching