Hello Everyone!

Great question.  Nitrogen is one of the essential elements (all living things need them, in specific amounts).  Nitrogen helps make up proteins, which is in our skin, muscles, and all parts of our body.  Nitrogen is also part of DNA, which is a big molecule that tells us what we look like.  So this is a very important chemical!!  Plants need Nitrogen too.  You can get more information about Nitrogen needs of plants at this reader-friendly website.  The problem comes in when we eat foods that come from plants and animals, which all have nitrogen in their proteins.  Too many molecules that have nitrogen, like NH₄⁺ (ammonia) and NO₃^- (nitrates) in our system is poisonous to us. 

 WHAT DO YOU THINK WOULD HAPPEN IF YOU COULDN'T PEE FOR OVER A DAY???

Plants, however, use these molecules to make their leaves and fruits grow.  So in controlled amounts, animal waste is good for plants.  However, like all living things, having too much of a good thing is a bad idea.  You may know of a bush or a plant that gets marked by dogs in your neighborhood-- you probably noticed that these plants don't look very healthy.  That's because animals that live on land (like dogs, people, and birds) want to keep water inside their body so they concentrate their urine before they get rid of it.  The concentrated urine has too many ammonia and nitrate compounds, and it burns up plants' roots, usually leading to death. 

Fresh-water fish, on the other hand, live in the water so they don't concentrate their urine.  Also, since they pee right in the water, the nitrogen molecules get diluted (spread out in all that water).  Taking a cupful of aquarium water and watering your favorite plant will help the plant by giving it water (which it always needs) along with a small amount of the nitrogen compounds to help its leaves grow. 

Using fish-pee water to grow better plants is called AQUAPONICS.  People like to use this big word becuase it sounds a lot better than saying "fish pee."

 Nao JacQuelynn Ueda Byrd Sheng