Soil : Not Just ‘ Dirt ’. What is Soil ?. Soils are a major component of the world’s ecosystems. They form at the interface of the Earth’s atmosphere , lithosphere (rocks), biosphere (living matter) and hdyrosphere (water). What is Soil ?.
Soils are a major component of the world’s ecosystems.
They form at the interface of the Earth’s atmosphere, lithosphere (rocks), biosphere (living matter) and hdyrosphere (water).
Soil is what forms the outermost layer of the Earth’s surface.
Soil comprise weathered bedrock (regolith), organic matter (both dead and alive), air and water.
LIKE LIVING SKIN OF THE EARTH!
Gases are exchanged between the soil surface and the air. Gases like oxygen andmethane are absorbed, while, while gases like carbon dioxide and nitrous oxide are released. The soilprovides a valuable carbon sink. The evaporation of soil moisture also affects air temperature andweather patterns.
Soil is by far the most biologically diverse part of the earth.
It containsa complex food web of prey, predators and decomposers.
Theseorganisms require the same elements we require: air, water, foodand shelter.
One teaspoon of healthy soil may contain:
• Bacteria- 100 million to 1 billion
• Fungi- up to 100 yards of fungal hyphae
• Protozoa- several thousand
• Nematodes- up to several hundred
• Arthropods (insects,spiders,centipeds)-500-2000
• Earthworms-arid soils may have none to several
O – Organic Horizon:
l - undecomposed litter
f – party decomposed litter
h – well decomposed humus
A – Mixed mineral-organic Horizon:
h – humus
p – ploughed in field or garden
g – gleyed or waterlogged
E - Eluvial or leached Horizon:
a – strongly leached,
and ash coloured
b – weakly bleached,
B – Illuvial or deposited
Fe – iron deposited
t – clay deposited
h – humus deposited
C – Bedrock or parent material
r – rock
u – unconsolidated loose
Soil is formed from rocks and decaying plants and animals.
Soil forming process consists of:
Therefore soils are open systemsin a steady-state equilibrium
Natural processes can take 500 years to form one inch of top soil.
Soils are vital to humans, but take a long time to develop, so should be considered a non-renewable resource
“The soil is the great connector of lives, the source and destination of all. It is the healer and restorer and resurrector, by which disease passes into health, age into youth, death into life. Without proper care for it we can have no community, because without proper care for it we can have no life.” ― Wendell Berry, The Unsettling of America: Culture and Agriculture
Symphony of Soil
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