Dirt: The Erosion of Civilizations - Kootenay Local Agricultural Society

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Republic was founded in 508 bc. The average farm still consisted of
roughly one to five acres (half a hectare to two hectares) of land, just
enough land to feed a family. Many prominent Roman family names were
derived from vegetables their ancestors excelled at growing. Calling a man
a good farmer was high praise in the republic. Cincinnatus was plowing his
fields when summoned to become dictator in 458 bc.
Early Roman farms were intensively worked operations where diversified
fields were hoed and weeded manually and carefully manured. The
earliest Roman farmers planted a multistory canopy of olives, grapes, cereals,
and fodder crops referred to as cultura promiscua. Interplanting of
understory and overstory crops smothered weeds, saved labor, and prevented
erosion by shielding the ground all year. Roots of each crop reached
to different depths and did not compete with each other. Instead, the multicrop
system raised soil temperatures and extended the growing season. In
the early republic, a Roman family could feed itself working the typical
plot of land by hand. (And such labor-intensive farming is best practiced
on a small scale.) Using an ox and plow saved labor but required twice as
much land to feed a family. As plowing became standard practice, the
demand for land increased faster than the population.
So did erosion. Extensive deforestation and plowing of the Campagna
increased hillslope erosion to the point that antierosion channels were
built to stabilize hillside farms. Despite such efforts, sediment-choked
rivers turned valley bottoms into waterlogged marshes as plows advanced
up the surrounding slopes. Malaria became a serious concern about 200 bc
when silt eroded from cultivated uplands clogged the Tiber River and the
agricultural valley that centuries before supported more than a dozen
towns became the infamous Pontine Marshes. Large areas of worn-out hills
and newly marshy valleys meant that formerly cultivated regions were
becoming pastures of little use beyond grazing. Once-flourishing towns
emptied as pastures supported fewer farmers than did the former fields.
Romans recognized that their wealth came from the earth; after all they
coined the name Mother Earth (mater terra). As did the Greeks before
them, Roman philosophers recognized the fundamental problems of soil
erosion and loss of soil fertility. But unlike Aristotle and Plato, who simply
described evidence for past erosion, Roman philosophers exuded confidence
that human ingenuity would solve any problems. Cicero crisply
summarized the goal of Roman agriculture as to create “a second world
within the world of nature.” Yet even as Roman farmers used deeper plows
and adapted their choice of crops to their denuded slopes, keeping soil on
graveyard of empires