Subject: Why does a pogo stick need more energy on a carpet than concrete surface

Dear Sir/Madam,
Good day to you.
I would like to know why a pogo stick needs more energy to perform (jump to a 
certain height)on grass field as compared to a concrete pavement? Does it have 
something to do with the elastic spring force in the spring or is it simply due 
to the type of collision of the base of the pogo stick with the surface of the 
ground? 
I have read through the archives but I am unable to relate the pogo stick with 
that of the the ball as the pogo stick has got a spring attached to the stick. 
Kindly explain the physics concept behind this. 
Thank you very much and have a nice day ahead.   

Re: Why does a pogo stick need more energy on a carpet than concrete surface