Dirt: The Erosion of Civilizations - Kootenay Local Agricultural Society

and, 30, 34–35, 36–37, 42, 47; relation
to productivity, 34–35, 84, 85–86, 93,
99, 106–7, 195, 198–99, 200; Sumerian
agriculture and, 39–40. See also
boom-and-bust cycle
Pory, John, 118
potassium, 19, 121, 316
potato blight in Ireland, 108–9
Potomac River, 140
poverty, war on, 176
Powell, John Wesley, 147
prairie ecosystems, 146, 147, 152, 206
prehistoric man, 28–31. See also ancient civilizations;
Bronze Age agriculture,
Old World; Neolithic agriculture,
Old World
Present State of Virginia, The, 121
productivity: population growth and,
34–35, 84, 85–86, 93, 99, 106–7, 195,
198–99, 200
productivity of soil: animal labor and, 35–
36; in developing countries, 198–99;
European soil improvement and, 98–
99; global warming and, 171; longterm
potential and, 235–36, 238–40;
organic methods and, 207–9; rise of
agriculture and, 34–36; small vs. large
farms and, 159; technological innovation
and, 180, 239; twentieth-century
increases in, 183, 197–98. See also
boom-and-bust cycle
profitability: high costs of mechanization
and, 150, 157, 158, 160, 161; of large vs.
small farms, 159; no-till methods and,
212; of organic vs. conventional systems
and, 159, 201, 207–10
Pueblo culture, 79–80
rainfall. See climate
Raleigh, Sir Walter, 118
Randolph, T. M., 125–26
Rapa Nui. See Easter Island
ratio of soil erosion to soil formation. See
balance in soil dynamics
reaper, 146
Reclus, Jean-Jacques-Élisée, 101–2
reforestation, 102, 103, 223
Reformation, and land reform, 92–93
Reganold, John, 208
religions, and earth-life relation, 27
Report on the Geology and Agriculture of the
State of Mississippi (1860), 188
resource depletion: economic systems and,
234–35, 237, 245; prehistory and, 34;
profitability calculation and, 209–10;
social collapse in South Pacific and,
217–23; USDA reports and, 192. See
also erosion; erosion rates; topsoil loss
Ricardo, David, 106
rice cultivation, 180–81
rills, 20
rivers. See silt accumulation
Rives, Alfred, 140
rock phosphate, 184, 193
rock weathering: earthworms and, 11–13;
physical processes and, 17; plants and,
13, 15; soil nutrients and, 18, 193, 194.
See also geology
Rodale Institute, Kutztown, Pennsylvania,
201, 208
Rofabards (Icelandic soil escarpments), 226,
227
Roggeveen, Jakob, 217
Rolfe, John, 118
Roman Empire, 55–67; agricultural practices
in, 58–62, 93; boom-and-bust
cycles in Europe and, 88–89; collapse
of, 63, 66–67, 88, 89, 189; the Nile
and, 67–68; slave labor and, 60, 61,
63, 234; soil erosion in, 58, 62–63
Roosevelt, Franklin D., 152
Rothamsted farm estate, 183–84, 201,
207–8
Ruffin, Edmund: Essay on Calcareous
Manures, 129–31
Russian agriculture, 109, 163–65
Rutherford, Daniel, 183
salinization of land: alkali soils and,
190–91; irrigation and, 39, 40, 43,
190–91
saltpeter (potassium nitrate), 121
sandy soil, 17, 182
scale of society, and responsiveness, 224,
237–38
Scotland, 87–88
index 281