Dirt: The Erosion of Civilizations - Kootenay Local Agricultural Society

Soil husbandry began to be seen as the key to productive, profitable
farming. Gervase Markham, one of the first agricultural writers to write in
English instead of Latin, described soils as various mixtures of clay, sand,
and gravel. What made good soil depended on the local climate, the character
and condition of the soil, and the local plants (crops). “Simple Clays,
Sands, or Gravels together; may be all good, and all fit to bring forth
increase, or all ...barren.” Understanding the soil was the key to understanding
what would grow best, and essential to keeping a farm productive.
“Thus having a true knowledge of the Nature and Condition of your
ground, ...it may not only be purged and clensed ...but also so much
bettered and refined.” 2
Prescribing steps to improve British farms, Markham recommended
using the right type of plow for the ground. He advised mixing river sand
and crushed burned limestone into the soil, to be followed by the best
manure to be had—preferably ox, cow, or horse dung. In describing procedures
for improving barren soils, Markham advocated growing wheat or
rye for two years in a field, and then letting sheep graze and manure it for
a year. After the sheep, several crops of barley were to be followed in the
seventh year by peas or beans, and then several more years as pasture. After
this cycle the ground would be much improved for growing grain. The key
to sustaining soil fertility was to alternate livestock and crops on the same
piece of ground.
Equally important, although it received less attention, was preventing
erosion of the soil itself. Markham advised plowing carefully to avoid collecting
water into erosive gullies. Good soil was the key to a good farm, and
keeping soil on the farm required special effort even on England’s gentle
rolling hills.
Almost half a century later, on April 29, 1675, John Evelyn presented a
“Discourse on Earth, Mould and Soil” to England’s Royal Society for the
Improvement of Natural Knowledge. In addressing what he feared could
be considered a topic unworthy of the assembled luminaries he invited the
society’s fellows to descend from contemplating the origin of heavenly
bodies and focus instead on the ground beneath their feet. He implored
them to consider both how soil formed and how the nation’s long-term
prosperity depended on improving the kingdom’s dirt.
Evelyn described how distinct layers of topsoil and subsoil developed
from the underlying rock. “The most beneficial sort of Mould or Earth,
appearing on the surface ...is the natural (as I beg leave to call it)
underturf-Earth and the rest which commonly succeeds it, in Strata’s or
let them eat colonies 95