Those who suggest that after use, an area would be good for crops, are not far from the truth.
Maybe not initially, because the explosives in such mines can be quite toxic. But a GM crop could do two things that would turn it into prime farmland. The first is that the crop could both uptake such toxic chemicals, and change color if it does uptake them. The second is that the crop could be like alfalfa, and put nitrogen back into the soil.
Even with the first season, the crop, except for those plants that had changed color, could be fed as nutritional fodder to animals. Then the soil would be ready to produce a high quality food plants the following year.
Probably the best crop for arid Africa is seed amaranth and quinoa, which are very hardy and can produce a large amount of high protein, high amino acid seed, as much as a kilogram per seed head. It was used extensively in ancient times, as a pseudo-grain, but its use was discouraged by Europeans more familiar with wheat and maize.
Plus it can taste any way you want it too.