Answer:
The crop-lien system was another way Southerners tried to boost their economy. In exchange for seeds, food, tools, and other necessities, farmers would provide a "lien" on their crops from the next harvest.
However, many merchants that provided for this system saw that they were the only ones who could do so. In the absence of competition, these merchants could charge ridiculously high interest rates, as high as 50%. If a farmer had a bad couple of years with his harvest, he would be trapped in a cycle of debt from which he could never escape. This was a common result.
This system also lead to an increased production of cash crops like cotton. After a few years of harvesting cotton, the soil would be depleted of nutrients, and nothing else could be grown on that land. While the farmers could possibly pay off their debt, they would be left with barren soil that could grow nothing else.
Sharecropping was a similar farming system found in the South after the Civil War. Southern planters would rent out land to former slaves and poor whites, in exchange for labor on the land they were given. These planters would charge a credit on the family's next harvest for the necessities of life as well as living on the land. This system was often abused by the planters; they charged high interest rates, and often controlled the lives of the people who worked for them. It wasn't a very good system, but it allowed Southern blacks and poor whites to make a modest living, even more so than the crop-lien system.