Soil pH

The soil pH is a measure of the acidity or alkalinity in soils. pH is defined as the negative logarithm (base 10) of the activity of hydronium ions (H+
or, more precisely, H
3O+
aq) in a solution. In water, it normally ranges from -1 to 14, with 7 being neutral. A pH below 7 is acidic and above 7 is alkaline. Soil pH is considered a master variable in soils as it controls many chemical processes that take place. It specifically affects plant nutrient availability by controlling the chemical forms of the nutrient. The optimum pH range for most plants is between 5.5 and 7.0, however many plants have adapted to thrive at pH values outside this range.

Classification of soil pH ranges

The United States Department of Agriculture Natural Resources Conservation Service, formerly Soil Conservation Service classifies soil pH ranges as follows:

Sources of soil pH

Sources of Acidity

Acidity in soils comes from H⁺ and Al³⁺ ions in the soil solution and sorbed to soil surfaces. While pH is the measure of H⁺ in solution, Al³⁺ is important in acid soils because between pH 4 and 6, Al³⁺ reacts with water (H₂O) forming AlOH²⁺, and Al(OH)₂⁺, releasing extra H⁺ ions. Every Al³⁺ ion can create 3 H⁺ ions. Many other processes contribute to the formation of acid soils including rainfall, fertilizer use, plant root activity and the weathering of primary and secondary soil minerals. Acid soils can also be caused by pollutants such as acid rain and mine spoilings.

Soil

Soil is the mixture of minerals, organic matter, gases, liquids, and the countless organisms that together support life on Earth. Soil is a natural body known as the pedosphere and which performs four important functions: it is a medium for plant growth; it is a means of water storage, supply and purification; it is a modifier of Earth's atmosphere; it is a habitat for organisms; all of which, in turn, modify the soil.

Soil is considered to be the "skin of the Earth" and interfaces with its lithosphere, hydrosphere, atmosphere, and biosphere. Soil consists of a solid phase (minerals and organic matter) as well as a porous phase that holds gases and water. Accordingly, soils are often treated as a three-state system of solids, liquids, and gases.

Soil is the end product of the influence of the climate, relief (elevation, orientation, and slope of terrain), organisms, and its parent materials (original minerals) interacting over time. Soil continually undergoes development by way of numerous physical, chemical and biological processes, which include weathering with associated erosion.

Soil (manga)

Soil is a manga series written and illustrated by Atsushi Kaneko. It was adapted into a Japanese television drama series in 2010. It has been published in French by Ankama.

Characters

Reception

The manga was nominated for Best Crime Comic at the 2012 Angoulême International Comics Festival and for Best Comic at the 2013 edition.

References

External links

System of a Down

System of a Down, often shortened to SOAD or System, is a four-piece Armenian-American rock band formed in 1994 in Glendale, California, in the United States. The band currently consists of Serj Tankian (lead vocals, keyboards), Daron Malakian (vocals, guitar), Shavo Odadjian (bass, backing vocals) and John Dolmayan (drums).

The band achieved commercial success with the release of five studio albums, three of which debuted at number one on the Billboard 200. System of a Down has been nominated for four Grammy Awards, and their song "B.Y.O.B." won the Best Hard Rock Performance of 2006. The group went on hiatus in August 2006 and reunited in November 2010, embarking on a tour for the following three years. System of a Down has sold over 40 million records worldwide.

History

Soil (1992–1994)

Serj Tankian and Daron Malakian attended Rose and Alex Pilibos Armenian School as children, although due to their eight-year age difference they did not meet until 1992 while working on separate projects at the same recording studio. They formed a band named Soil with Tankian on vocals and keyboards, Malakian on vocals and guitar, Dave Hakopyan (who later played in The Apex Theory/Mt. Helium) on bass and Domingo "Dingo" Laranio on drums. The band hired Shavo Odadjian (another Rose and Alex Pilibos alumnus) as manager, although he eventually joined Soil as rhythm guitarist. In 1994, after only one live show, and one jam session recording, Hakopyan and Laranio left the band, feeling that it was not going anywhere.