Why did many former slaves enter into sharecropping contracts that were designed to keep them poor?

Many former salves expected the federal government to give them a certain amount of land as compensation for all the work they had done during the slave era. During Reconstruction, however, the conflict over labor resulted in the sharecropping system, in which black families would rent small plots of land in return for a portion of their crop, to be given to the landowner at the end of each year.