WordNet

to a very great extent or degree; "the idea is so obvious"; "never been so happy"; "I love you so"; "my head aches so!"
(usually followed by `that'
in a manner that facilitates; "he observed the snakes so he could describe their behavior"; "he stooped down so he could pick up his hat"
in such a condition or manner, especially as expressed or implied; "Theyre happy and I hope they will remain so"; "so live your life that old age will bring no regrets"
in the same way; also; "I was offended and so was he"; "worked hard and so did she"
to a certain unspecified extent or degree; "I can only go so far with this student"; "can do only so much in a day"
on the surface; "surface materials of the moon"
the outer boundary of an artifact or a material layer constituting or resembling such a boundary; "there is a special cleaner for these surfaces"; "the cloth had a pattern of red dots on a white surface"
the outermost level of the land or sea; "earthquakes originate far below the surface"; "three quarters of the Earths surface is covered by water" (同)Earth''s surface
a superficial aspect as opposed to the real nature of something; "it was not what it appeared to be on the surface"
the extended two-dimensional outer boundary of a three-dimensional object; "they skimmed over the surface of the water"; "a brush small enough to clean every dental surface"; "the sun has no distinct surface"
come to the surface (同)come_up, rise up, rise
the part of the earths surface consisting of humus and disintegrated rock (同)dirt
the act of soiling something (同)soilure, dirtying
emerging to the surface and becoming apparent

PrepTutorEJDIC

《様態の指示》『そういうふうに』,『そのように』・《補語に用いて》『そのようで』,そうで・《程度》『それほど』,そんなに・《強意として》《話》『非常に』,『とても』,たいへん・《前に述べたことの内容に対する同意を表して;「so+主語+[助]動詞」》『その通りで』,『本当に』,確かに,おっしゃるとおり・《肯定文を受けて;「so+[助]動詞+主語」の語順で》…『もまた』,『も同様に』・《as~, so…で》~と同じように…,(~のように)そのように・《目的を表して》…『するように』・《理由・結果を表して》『その結果』,それで・《文・節の頭に用いて》『それで』,だから・《驚き・賛成・嫌悪・疑いなどを表して》そうか,そうなんだ,どうかな,まさか・それでよし
=sol
(物の)表面,外面;水面 / 《比喩的に》『うわべ』,見かけ / 『表面(水面)の,』表面(水面)に関する / 《比喩的に》『うわべだけの,』見かけだけの / 陸(水)上輸送の / (沈んでいたものが)表面に浮上する;《話》《おどけて》(寝ていた人が)起きる / (…で)…‘に'表面をつける,〈道路〉‘を'舗装する《+名+with+名》
〈U〉(植物の成長に適する)『土』,土壌(どじょう) / 〈U〉(特殊な)土 / 〈U〉〈C〉《気取って》国,地方;《the~》土地,農地
〈衣服など〉‘を'汚す,きたくなくする / 《比喩(ひゆ)的に》〈名声など〉‘を'けがす / 〈衣服などが〉汚れる,きたなくなる / 汚れ,汚点,しみ / (人の)汚物

Wikipedia preview

出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2014/05/19 12:38:29」(JST)

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[Wiki en表示]

Surface runoff, also called nonpoint source pollution, from a farm field in Iowa during a rain storm.

Topsoil as well as farm fertilizers and other potential pollutants run off unprotected farm fields when heavy rains occur.

Topsoil is the upper, outermost layer of soil, usually the top 2 inches (5.1 cm) to 8 inches (20 cm). It has the highest concentration of organic matter and microorganisms and is where most of the Earth's biological soil activity occurs.

Importance

Plants generally concentrate their roots in and obtain most of their nutrients from this layer. The actual depth of the topsoil layer can be measured as the depth from the surface to the first densely packed soil layer known as subsoil.

Classification

In soil classification systems, topsoil is known as the "A Horizon," therefore, it is the very top layer.^[1]

Evaluation

When starting a gardening project, it is very crucial to check whether or not the Soil is satisfactory. Following are the desired levels of Topsoil nutrients.^[2]

Category	Desired Results
pH Level	5.8 to 6.2
Phosphorus (P-I)	Index of 50
Potassium (K-I)	Index of 50
Calcium (Ca%)	40-60% of Cation Exchange Capacity (CEC)
Magnesium (Mg%)	8-10% of CEC
Base saturation (BS%)	60-80% of CEC
Manganese (Mn-I)	Index > 25
Zinc (Zn-I)	Index > 25
Copper (Cu-I)	Index > 25

The two common types of Topsoil are Bulk and Bagged Topsoil. The following table illustrates major differences between the two.^[2]

Topsoil Type	HM%^[3]	BS%	pH	P-I	K-I	Ca%	Mg%
Bulk	0.3	69	5.2	009	026	45	10
Bagged	0.7	78	5.8	166+	178	56	12.3

Commercial application

A variety of soil mixtures are sold commercially as topsoil, usually for use in improving gardens and lawns, e.g. container gardens, potting soil and peat. Another important yet not commonly known use for topsoil is for proper surface grading near residential buildings such as homes. "The ground around the home should slope down six inches for the first ten feet away from the home. This can often be done by adding topsoil (not sand or gravel)."^{[citation needed]}

Erosion

A major environmental concern known as topsoil erosion occurs when the topsoil layer is blown or washed away. Without topsoil, little plant life is possible. The estimated annual costs of public and environmental health losses related to soil erosion exceed $45 billion.^[4] Conventional agriculture encourages the depletion of topsoil because the soil must be plowed and replanted each year. Sustainable techniques attempt to slow erosion through the use of cover crops in order to build organic matter in the soil. The United States alone loses almost 3 tons of topsoil per acre per year.^[5] This is of great ecological concern as one inch of topsoil can take 500 years to form naturally.^[6] On current trends, the world has about 60 years of topsoil left.^[7] However, farmer and engineer P. A. Yeomans developed a technique known as Keyline design, which has been proven to convert subsoil into topsoil much faster; Yeomans published a book about the technique in 1954.

References

^ U.S. Department of Agriculture (USDA), Soil Survey Division Staff (1993). "Soil Survey Manual." USDA Handbook 18. Chapter 3.
^ ^a ^b Topsoil . North Carolina Department of Agriculture(July, 1995)
^ Percent humic matter is a measure of the portion of organic matter that has decomposed to form humic and fulvic acids. HM% represents the portion of organic matter that is chemically reactive. This value affects determinations of lime and herbicide rates. [1]
^ http://www.ce.cmu.edu/~gdrg/readings/2007/02/20/Pimental_EnvironmentalEnergeticAndEconomicComparisonsOfOrganicAndConventionalFarmingSystems.pdf
^ http://www.nrcs.usda.gov/technical/nri, "Summary Report, 2007 Natural Resources Inventory," Natural Resources Conservation Services, U. S. Department of Agriculture, December 2009, p. 97
^ James Smolka (May 1, 2001). "Eating Locally". Discover. Retrieved May 1, 2001.
^ "What If the World’s Soil Runs Out?". Time. December 14, 2012.

The lowdown on topsoil: It's disappearing
Mann, C (2008). "Our Good Earth". National Geographic Magazine 214 (3): 80–107.

External links

USDA Electronic Field Office Technical Guide - Detailed soil conservation guides tailored to individual states/counties
UK British Topsoil Suppliers Association - Detailed soil information guides

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