Your lawn can go yellow for a varity of reasons. Like when objects are placed on it the grass starts lacking sunlight and goes yellow. Or lack of water, too much pesticide or moles.
Maybe its not getting enough sunlight. Animal urine won't help either. If it starts going yellow water it or use lawn feeds.
Cutting grass does have a very harmful effect somtimes as when you cut it, it will lose a lot of moisture. So after cutting water it and or use lawn feed Grass can recover.wiki.answers.com»
Grass is turning yellow because it is SO wet :( The trees in the background are beginning to turn :).jpgmag.com»