Rocks in The Soil
Certain parent materials also contribute to soil acidification. Granites and their allied igneous rocks are called "acidic" because they have a lot of free quartz, which produces silicic acid on weathering. Also, they have relatively low amounts of calcium and magnesium. Some sedimentary rocks such as shale and coal are rich in sulfides, which, when hydrated and oxidized, produce sulfuric acid which is much stronger than silicic acid. Many coal spoils are too acidic to support vigorous plant growth, and coal gives off strong precursors to acid rain when it is burned. Marine clays are also sulfide-rich in many cases, and such clays become very acidic if they are drained to an oxidizing state.
Read more about this topic: Soil Acidification
Famous quotes containing the words the soil, rocks and/or soil:
“I am persuaded that the people of the world have no grievances, one against the other. The hopes and desires of a man who tills the soil are about the same whether he lives on the banks of the Colorado or on the banks of the Danube.”
—Lyndon Baines Johnson (1908–1973)
“The strongest wind cannot stagger a Spirit; it is a Spirit’s breath. A just man’s purpose cannot be split on any Grampus or material rock, but itself will split rocks till it succeeds.”
—Henry David Thoreau (1817–1862)
“Our own country furnishes antiquities as ancient and durable, and as useful, as any; rocks at least as well covered with lichens, and a soil which, if it is virgin, is but virgin mould, the very dust of nature. What if we cannot read Rome or Greece, Etruria or Carthage, or Egypt or Babylon, on these; are our cliffs bare?”
—Henry David Thoreau (1817–1862)