A three-year project investigating the use of compost derived from green waste will be completed in 2004. Preliminary benefits from using compost have already been demonstrated. A series of events aimed at farmers and growers wishing to improve the efficiency and sustainability of nutrient use on their farms. Aim of the workshops With increasing fertilizer costs and tougher legislation over nitrate pollution, green manures are set to play an important role in the future of soil fertility.
Soils can be deep, shallow, new, old, bright orange, black, or even blue (And anywhere in-between)! What soil looks like depends on the location that it forms in. It can take over 500 years to form an inch of topsoil on the surface!
Like humans, soils have different properties based on where they are from, and where they "grew up" (formed). Soils have 6 major horizontal layers, or horizons that can be present. These horizons are often present in different types of soil, but each area usually has soils that have similar properties if they are near each other. Soil particles are moved by water, wind, ice, or formed in place from the rocks.
Land and People
Take anything in your life and you can trace it back to soil. We could not survive without soils! While we are often not aware of it, soils really do directly or indirectly affect every part of our lives: from food, water and air availability and quality, to engineering implications to various essential ecosystem services, to influences on human cultures and careers. Soils produce our food: our crop plants are grown in soil, our livestock eat crops grown in soil, wildlife feeds on plants grown in soil, even fish eat plants, insects, etc, that at some point in their life-cycle were directly tied to soil.
The soil beneath my feet is important from several aspects; such as where should I build my home, from what will my house be made: brick or wood or adobe "From where does my water come" Underground aquifers or rivers, and how is it cleaned?
Soils are complex mixtures of minerals, water, air, organic matter, and countless organisms that are the decaying remains of once-living things. It forms at the surface of land - it is the "skin of the earth." Soil is capable of supporting plant life and is vital to life on earth.
The unconsolidated mineral or organic material on the immediate surface of the earth that serves as a natural medium for the growth of land plants.
The unconsolidated mineral or organic matter on the surface of the earth that has been subjected to and shows effects of genetic and environmental factors of: climate (including water and temperature effects), and macro- and microorganisms, conditioned by relief, acting on parent material over a period of time.
So then, what is dirt?
Dirt is what gets on our clothes or under our fingernails. It is soil that is out of place in our world - whether tracked inside by shoes or on our clothes. Dirt is also soil that has lost the characteristics that give it the ability to support life - it is dead. Soil performs many critical functions in almost any ecosystem.
There are seven general roles that soils play:
Soils serve as media for growth of all kinds of plants.
Soils modify the atmosphere by emitting and absorbing gases (carbon dioxide, methane, water vapor, and the like) and dust.
Soils provide habitat for animals that live in the soil (such as groundhogs and mice) to organisms(such as bacteria and fungi), that account for most of the living things on Earth.
Soils absorb, hold, release, alter, and purify most of the water in terrestrial systems.
Soils process recycled nutrients, including carbon, so that living things can use them over and over again.
Soils serve as engineering media for construction of foundations, roadbeds, dams and buildings, and preserve or destroy artifacts of human endeavors.
Soils act as a living filter to clean water before it moves into an aquifer.
There are many soil properties that help us describe and manage soils.
Some of the important physical properties are described below.
The particles that make up soil are categorized into three groups by size - sand, silt, and clay. Sand particles are the largest and clay particles the smallest. Most soils are a combination of the three. The relative percentages of sand, silt, and clay are what give soil its texture. A clay loam texture soil, for example, has nearly equal parts of sand, slit, and clay.
Sand - 2.0 to 0.05 mm
Silt - 0.05 to 0.002 mm
Clay - less than 0.002 mm
There are 12 soil textural classes represented on the soil texture triangle on the right. This triangle is used so that terms like "clay" or "loam" always have the same meaning. Each texture corresponds to specific percentages of sand, silt, or clay. Knowing the texture helps us manage the soil.
Soil structure is the arrangement of soil particles into small clumps, called peds or aggregates. Soil particles (sand, silt, clay and even organic matter) bind together to form peds. Depending on the composition and on the conditions in which the peds formed (getting wet and drying out, or freezing and thawing, foot traffic, farming, etc.), the ped has a specific shape. They could be granular (like gardening soil), blocky, columnar, platy, massive (like modeling clay) or single-grained (like beach sand). Structure correlates to the pore space in the soil which influences root growth and air and water movement.
Soil colour is influenced primarily by soil mineralogy - telling us what is in a specific soil. Soils high in iron are deep orange-brown to yellowish-brown. Those soils that are high in organic matter are dark brown or black. Colour can also tell us how a soil "behaves" - a soil that drains well is brightly colored and one that is often wet and soggy will have a mottled pattern of grays, reds, and yellows.
There are different types of soil, each with its own set of characteristics. Dig down deep into any soil, and you'll see that it is made of layers, or horizons (O, A, E, B, C, R). Put the horizons together, and they form a soil profile. Like a biography, each profile tells a story about the life of a soil. Most soils have three major horizons (A, B, C) and some have an organic horizon (O). The horizons are:
O -(humus or organic) Mostly organic matter such as decomposing leaves. The O horizon is thin in some soils, thick in others, and not present at all in others.
A -(topsoil) Mostly minerals from parent material with organic matter incorporated. A good material for plants and other organisms to live.
E - (eluviated) - Leached of clay, minerals, and organic matter, leaving a concentration of sand and silt particles of quartz or other resistant materials - missing in some soils but often found in older soils and forest soils.
B - (subsoil) Rich in minerals that leached (moved down) from the A or E horizons and accumulated here.
C - (parent material) The deposit at Earth's surface from which the soil developed.
R - (bedrock) A mass of rock such as granite, basalt, quartzite, limestone or sandstone that forms the parent material for some soils - if the bedrock is close enough to the surface to weather. This is not soil and is located under the C horizon.
Soil degradation is a human-induced or natural process which impairs the capacity of soil to function. As an example, in 3000 BC, the Sumerians built large cities in the deserts of Southern Mesopotamia. Using irrigation, they farmed the desert soils and created large food surpluses that made their civilization possible. But around 2200 BC, the civilization collapsed. Scientists debate why, but one reason may be tied to the soil. Irrigating in dry climates can cause a buildup of salt, a process called salinisation. Few crops can tolerate salt. The soil in this region still remains too salty to grow crops. Other activities that degrade the soil include contamination, desertification, and erosion.
Soil is Inter-Disciplinary
Soil has been a defining component of cultures since the beginning of civilization. Some of the first written words were recorded on clay tablets and water was carried in clay pitchers. It provides the base for all buildings (although some may be able to support a skyscraper and some others may not be able to support your weight), it holds the clues of past cultures (to be revealed by archaeologists or erosion), it supports the web of life (connecting all ecosystems), provides materials to build houses, is a source of nutraceuticals (definite in the American Heritage Dictionary as a food or naturally occurring food supplement thought to have a beneficial effect on human health), and of course, provides the base for our food, fiber, feed, and even some biofuels.
Find out about your soil. Download mySoil.
mySoil is a new free smartphone app from the BGS and the Centre for Ecology & Hydrology.
Use mySoil to view a map of the soil parent material- the underlying geological material- in your local area, retrieve descriptions about the soil deptyh, texture, pH and organic matter content, and explore vegetation habitat data across Britain.
MySoil lets you take a soil properties map of Britain with you wherever you go, helping you learn about the soil beneath your feet and is available for download for iPhone or iPad.
But if you don't have one of these you can still find out about your soil by visiting.
MySoil is for anyone with an interest in the soil of Britain; including gardeners, vegetable growers, allotment owners, farmers and agricultural specialists, schools and collage students, environmentalists and land-use planners.
To illustrate the amount of soil on Earth.
Pretend that an apple is the planet Earth, round, beautiful, and full of good things. Notice its skin, hugging and protecting the surface, Water covers approximately 75% of the surface. Cut the apple in quarters. Put three quarters (75%) aside.
The three quarters (75%) you just removed represents how much of the earth is covered with water (oceans, lakes, rivers, streams). What is left (25%) represents the dry land. 50% of that dry land is desert, polar or mountainous regions, where it is to hot, to cold or to high to be productive.
So cut that dry land quarter in half.
When 50% is removed this is what is left 12.5% of the original. Of that 12.5%, 40% is severely limited by terrain, fertility or excessive rainfall. It is to rocky, steep, shallow, poor or to wet to support food production.
Cut that 40% portion away. You are left with 10% of the apple. Now peel the skin from the tiny remaining sliver.
The remaining 10% (approximately, there is difficulty within the scientific community in coming up with an exact figure)- this small fragment of the land area represents the soil we depend on for the worlds food supply. This fragment competes with all other needs, housing, cities, schools, hospitals, shopping centres, lands fills, etc.
Courtesy of: The Natural Resources Conservation Service, Syracuse, NY, U.S. Department of Agriculture.