How did sharecropping create a cycle of poverty for african-americans in the south

So sharecropping was in a way, like slavery. But first to understand why blacks had to sharecrop, I'll tell you a bit about the black codes.
The black codes banned almost every other form of working for blacks, unless you had a permit (and who do you think gave out permits?). They also said that blacks had to be employed by a white person at all times, and couldn't travel without permission from their boss. Which means they couldn't quit. So again, like slavery.
Now, moving on to sharecropping. Sharecropping was when a person was given a small house and a plot of land. They were to grow crops on their land, and give a share of them to their employer. In return, the employer gave them a small pay.
Because of the black codes and the tiny pay that they received, they couldn't live on their own, so it created a cycle of poverty. 
Hope this helps! Have a great day!