Dirt: The Erosion of Civilizations - Kootenay Local Agricultural Society

grazing animals doubled; the human population tripled. New French
plantations to grow cotton and peanuts as cash crops pushed subsistence
farmers onto smaller areas of marginal land. Fallow periods were reduced
or eliminated and crop yields began to fall. Ground exposed beneath
parched crops dried out and blew away with the wind.
Then in 1972, no rain fell and no grass grew. Livestock mortality was
high where continuous overgrazing left little grass from the previous year.
The few fruit trees that survived bore little fruit. Millions of refugees
flooded into huge shantytowns. Between a hundred thousand and a quarter
of a million people died of hunger. While the drought was the immediate
cause of this disaster, colonial-era cultural and economic changes led
to exploitation of the Sahel and allowed the population to grow beyond
what the land could sustain during dry spells. It didn’t help that crops
grown on large plantations were still exported during the famine.
Destruction of perennial plant cover from overgrazing causes desertification
by exposing the soil surface to erosion from wind and rain. Erosion
rates of half an inch to three-quarters of an inch per year have been
reported in semiarid regions once the native perennials are gone. The
process is generally irreversible; plants cannot survive the dry season without
the water-holding topsoil. Once the soil is gone, the ability to support
people disappears too.
During the famine, an image taken by a NASA satellite provided stark
confirmation of the human hand in creating the crisis. A mysterious green
pentagon in the center of the drought-ravaged zone turned out to be a
quarter-million-acre ranch separated from the surrounding desert by a
simple barbed wire fence. The ranch, established in the same year that the
drought began, was divided into five sectors, with the cattle allowed to
graze one sector each year. Limiting the intensity of grazing prevented the
problems that brought starvation to the surrounding countryside.
Desertification began in both the Sahel and North Africa during the
1950s and 1960s, despite above average North African rainfall during these
years. Large state-owned ranches established during the 1960s showed no
evidence of desertification if stocked at the estimated long-term capacity of
the rangelands. Although drought reinforces the effects of land degradation,
climate variability is not the root cause. Droughts naturally recur in
semiarid regions. Drought-adapted ecosystems and societies weathered
them in the past. Traditional African pastoralists practiced de facto population
control through social structures and rules developed over centuries
of alternating scarcity during droughts and abundance during wetter times.
dust blow 167