Not all of South Sudan is not being farmed. The centre of the country is mainly a flat plain, and it's affected by flood waters, but near the borders of Ethiopia, Kenya, Uganda, these are mainly highlands, with an altitude of maybe 800 metres and above, and this is where most of the farming takes place.
Most of the farming is for subsistence. A family prepares a small plot, enough grain for the family. Government has not come up with the policies to encourage people to farm to create some surplus, to earn money from that surplus, and maybe send kids to school. Most of the farming that is done is for personal use, not for commerce. But Uganda has understood that if you work hard, you will earn some money, and that's why in most towns that is what Uganda is supplying. In the rural areas, many people farm for themselves and they are self-sufficient. But the donor food is going to the conflict areas because they don't have the time to cultivate. Most of the time they are on the move or in detention camps. If you go to Malakal, Juba, and Wau and you find these IDPs—internally displaced persons—they don't even have the luxury of going to till the land outside the camps. I think most of the food and assistance goes to people who have been displaced.