Sharecropping started WAY before the Civil War. My family came over here as endentured servants in the late 1700's and worked other people's land for 100 years. Instead of being out-right slaves, my ancestors worked to pay of the debts of everyday life (incurred to the landowner) that slaves got for free. The Civil War esentially freed my ancestors just as blacks were freed.
Indentured servants and some share cropping certainly did exist before the Cival War, even more people who should get reperations. However it didn't end after the Civil War, instead it got much, much worse. The term redneck refers to the Irish and Scots Irish, who worked the feld all day and the back of their necks were always sunburn't. The end of slavery propted many plantation owners to employ hundreds of share croppers to replace slaves, and the practice was made worse by requiring that they buy all products from the landowner, and borrow all from him that they cannot pay. Shortly after signing the contract the landowner raised his prices to insure that the sharecropper would never be out of debt. Thus it became legalized slavery.