Share cropping is when a farmer rents a piece of land not by paying with money, but paying with a section of their crops grown. A lot of the time this was not fair and the owner of the land demanded too much from the farmer.
Since the amount of crop grown has been diminished, there usually isn't enough money to pay for other expenses, such as farming equipment and housing, causing the farmer to rent more land to grow crops on, but then the price of having the land goes up. This is the cycle of poverty created by sharecropping. Hope this helps!