It Must be true. We've been told it so many times. The over-farmed and overgrazed soils of Africa, especially on the fringes of the Sahara, are losing their fertility and eroding away. As the population grows, poor farmers are mining the last goodness from their soils. Their animals graze the grasslands away to nothing and the desert sands move in. Environmentalists say it; development economists say it; politicians say it; soil scientists say it.
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