Dirt: The Erosion of Civilizations - Kootenay Local Agricultural Society

A few miles in from the forest edge, family farms and small villages gave
way to cattle ranches. As subsistence farmers pushed farther into the forest,
ranchers took over abandoned farms. Cows can graze land with soil too
poor to grow crops, but it takes a lot of ground to support them. Largescale
cattle grazing prevents the forest from regrowing, causing further erosion
and sending frontier communities farther and farther into the jungle
in an endless push for fresh land. The vicious cycle is plainly laid out for
all to see.
Instead of clearing small patches of forest for short periods, immigrants
to the Amazon are clearing large areas all at once, and then accelerating
erosion through overgrazing, sucking the life from the land. The modern
cycle of forest clearing, peasant farming, and cattle ranching strips off topsoil
and nearly destroys the capacity to recover soil fertility. The result is
that the land sustains fewer people. When they run out of productive soil,
they move on. The modern Amazon experience reads a lot more like the
history of North America than we tend to acknowledge. Yet the parallel is
as clear as it is fundamental.
Between forty million and one hundred million people lived in the
Americas when Columbus “discovered” the New World—some four million
to ten million called North America home. Native Americans along
the East Coast practiced active landscape management but not sedentary
agriculture. Early colonists described a patchwork of small clearings and
the natives’ habit of moving their fields every few years, much like early
Europeans or Amazonians. While there is emerging evidence of substantial
local soil erosion from native agriculture, soil degradation and erosion
began to transform eastern North America under the new arrivals’ more
settled style of land use.
Intensive cultivation of corn quickly exhausted New England’s nutrientpoor
glacial soils. Within decades, colonists began burning the forest to
make ash fertilizer for their fields. With more people crowded into less
space, New Englanders ran out of fresh farmland faster than their neighbors
in the South. Early travelers complained about the stench from fields
where farmers used salmon as fertilizer. And in the South, tobacco dominated
the slave-based economies of Virginia and Maryland and soil
exhaustion dominated the economics of tobacco cultivation. Once individual
family farms coalesced into slave-worked tobacco plantations, the
region became trapped in an insatiable socioeconomic system that fed on
fresh land.
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