Answer:
Brown I am and much admired. Many horses have I tried. Tire a horse and worry a man, tell me this riddle if you can. What am I?
I am lighter than the material I am made of. You see parts of me but more of me is hidden underneath.
What has roots that nobody sees and is taller than trees. Up up up it goes and yet never grows?
You cannot keep me until you have given me. What am I?
To cross the water, I'm the way. For water I'm above, I touch it not and truth to say, I neither swim nor move. What am I?
Whoever made me don't want me. Whoever bought me don't need me. Whoever use me don't know me.