- It is a deeply entrenched belief that historic land use led to land degradation in the desert belts. Supposedly, overgrazing and farming caused erosion, and irrigation led to salinization. Considering the gaps in settlement history, mismanagement is considered a prime reason for abandonment [1–3]. If this is so, Progressive Development might be doomed to fail, because the soils are already degraded and will inevitably degrade further. Climate variations, however, can also lead to degradation, and might have caused the fluctuations of settlement history. The correct assessment of the past will be most important for evaluating the impact of Progressive Development. This and the geographic law of soil zonality allow predicting how soils and the environment will develop under irrigation and permanent vegetation.