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Soil as an

important element

Naveen

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intro

Soils are the basic resource upon which allterrestrial life depends. The bounty from ourelds and forests, and the quality of ourlakes and streams, is dependent upon thequality of our soils. Many of theenvironmental decisions about using aresource are based on the kind of soil andthe ability of the soil to support that

resource use.hether natural or man!mi"ed, soils have physical, environmental, andchemical properties. These are all important to the health of a growingmedium. #hysical properties include organic matter, water, drainage,and aeration. $nvironmental characteristics include light andtemperature. %hemical elements include the ph balance, and thepresence &or not' of phosphorous, nitrogen, and potassium, which areall critical elements for plants.

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Soil structure

Soil structure is the arrangement of soil particles into groupings.These groupings are called peds or aggregates, which oftenform distinctive shapes typically found within certain soilhori(ons. )or e"ample, granular soil particles are characteristicof the surface hori(on.

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SOIL PHYSICAL AND CHEMICAL PROPERTIES

*. Soil physicalproperties +ori(onation! Soil hori(ons- are discrete layers that make up a

soil prole. They are typically parallel with the ground surface.n some soils, they show evidence of the actions of the soilforming processes.

soil color! Soil color is typically described using some form ofcolor reference chart, such as the munsell color chart. /singthe munsell system, color is described in reference to thecolor0s hue-, value-, and chroma-. +ue describes where inthe color spectrum the soil color e"ists, which for soils includesthe colors yellow, red, blue, green, and gray.

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soil te"ture! Soil te"ture refers to the proportion of the soilseparates- that make up the mineral component of soil. Theseseparates are called sand, silt, and clay. These soil separateshave the following si(e ranges1

Sand 2 34 to 5.56 mm

Silt 2 5.56 to 5.554 mm

%lay 2 35.554 mm

soil structure! The soil separates can become aggregatedtogether into discrete structural units called peds-. These peds

are organi(ed into a repeating pattern that is referred to as soilstructure. 7etween the peds are cracks called pores- throughwhich soil air and water are conducted.

soil consistence! The soil separates can become aggregatedtogether into discrete structural units called peds-. These pedsare organi(ed into a repeating pattern that is referred to as soilstructure. 7etween the peds are cracks called pores- through

which soil air and water are conducted.

http://www.nrcs.usda.gov/wps/portal/nrcs/detail/nj/home/?cid=nrcs141p2_018993#Soil_Texture_http://www.nrcs.usda.gov/wps/portal/nrcs/detail/nj/home/?cid=nrcs141p2_018993#Soil_Texture_http://www.nrcs.usda.gov/wps/portal/nrcs/detail/nj/home/?cid=nrcs141p2_018993#Soil_Structure_http://www.nrcs.usda.gov/wps/portal/nrcs/detail/nj/home/?cid=nrcs141p2_018993#Soil_Structure_http://www.nrcs.usda.gov/wps/portal/nrcs/detail/nj/home/?cid=nrcs141p2_018993#Soil_Consistence_http://www.nrcs.usda.gov/wps/portal/nrcs/detail/nj/home/?cid=nrcs141p2_018993#Soil_Consistence_http://www.nrcs.usda.gov/wps/portal/nrcs/detail/nj/home/?cid=nrcs141p2_018993#Soil_Consistence_http://www.nrcs.usda.gov/wps/portal/nrcs/detail/nj/home/?cid=nrcs141p2_018993#Soil_Consistence_http://www.nrcs.usda.gov/wps/portal/nrcs/detail/nj/home/?cid=nrcs141p2_018993#Soil_Structure_http://www.nrcs.usda.gov/wps/portal/nrcs/detail/nj/home/?cid=nrcs141p2_018993#Soil_Structure_http://www.nrcs.usda.gov/wps/portal/nrcs/detail/nj/home/?cid=nrcs141p2_018993#Soil_Texture_http://www.nrcs.usda.gov/wps/portal/nrcs/detail/nj/home/?cid=nrcs141p2_018993#Soil_Texture_

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SOIL CHEMICALPROPERTIES

cation e"change capacity! The cation e"change capacity-, orcec-, of a soil is a measurement of the magnitude of thenegative charge per unit weight of soil, or the amount of cationsa particular sample of soil can hold in an e"changeable form.

The greater the clay and organic matter content, the greaterthe cec should be, although di8erent types of clay minerals andorganic matter can vary in cec.

soil reaction &ph'!7y denition, ph- is a measure of the activehydrogen ion &h9' concentration. t is an indication of theacidity or alkalinity of a soil, and also known as soil reaction-.

The ph scale ranges from 5 to *:, with values below ;.5 acidic,and values above ;.5 alkaline. < ph value of ; is consideredneutral, where h9 and oh! are equal, both at a concentration of*5!; moles=liter. < ph of :.5 is ten times more acidic than a phof 6.5.

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Soil aggregation is animportant indicator ofthe workability of thesoil. Soils that arewell aggregated are

said to have goodsoil tilth.- The varioustypes of soil are

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Soil formation

Soil is the result of ve ma>or environmental elements blendedtogether. The ve elements, or soil!forming factors, that lead to thepattern of soils we observe are1

*' the parent material, the geologic material from which the soilwas originally formed?

4' the climate in which the material is found?

@' the relief or landscape properties upon which that material lay,such as the slope and aspect?

:' the organisms that can potentially live on or in the material?and

6' the length of time during which the previous four elementshave interacted.

. < unique combination of these ve factors produces a soil.

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Importance of soil

Soil is a vital part of the natural environment. t is >ust as importantas plants, animals, rocks, landforms, lochs and rivers.

t inAuences the distribution of plant species and provides a habitatfor a wide range of organisms.

t controls the Aow of water and chemical substances between theatmosphere and the earth, and acts as both a source and store forgases &like o"ygen and carbon dio"ide' in the atmosphere.

Soils not only reAect natural processes but also record humanactivities both at present and in the past. They are therefore part ofour cultural heritage.

The modication of soils for agriculture and the burial ofarchaeological remains are good e"amples of this.

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Importance of soil

Soil, together with the plant and animal life it supports, the rockon which it develops, its position in the landscape and theclimate it e"periences, form an ama(ingly intricate naturalsystem B more powerful and comple" than any machine thatman has created.

Soil may look still and lifeless, but this impression couldn0t befurther from the truth.

t is constantly changing and developing through time.

Soil is always responding to changes in environmental factors,along with the inAuences of man and land use.

Some changes in the soil will be of short duration andreversible, others will be a permanent feature of soildevelopment

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Role of architect in soil stu!

< landscape architect should at the very least equip themselves withthe basic scientic information about soils1 they should have a

knowledge of soil classication, soil te"ture and structural properties,

soil water movement,

soil fertility and soil ecology &micro!biology'?

fundamentally they should understand how soil properties strongly

inAuence the make!up of vegetation in a particular landscape. Dandscape architects should also have a basic knowledge of the

engineering properties of soils and how even minimal disturbance tosoil could negatively a8ect the structural and ecological functioningof that soil. n this regard, knowledge of soil remediation techniquesis also useful to landscape architects.

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T!pes of Soil an TheirProperties

Cla! soil"particles are very small and compact. Eardens withthese types of soil particles don0t work well because the air hasa hard time getting to the roots. The soil absorbs and holdswater and creates a drainage problem. This adversely a8ectshealthy root and plant growth.

San! soil"particles are large. The water and nutrients&particularly nitrogen' quickly drain away from the plant root

(one. Sandy soil is the opposite of clay soil.

Silt soil"is made up of ne particles. Dike clay the soil holdswater but doesn0t have good aeration around the roots.

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Alluvial soils-these are developed from alluvial parent material, transported anddeposited by moving water along the river course, blown by wind, moved by iceor gravitational force. The alluvial material deposited by sea water develops intocoastal alluvium. Indo-congenic alluvium and Brahmaputra alluvial soils representriverine alluvium of Himalayan rivers. They are the most extensive in India

Black soils-These are formed under arid to semi-arid climate and over Deccanbasalt. lso !nown as "egur or Blac! #otton soil, these are dar! grey to blac! incolour with high clay content. They have impeded drainage and poor aerationduring monsoon with high water-retention capacity. These are highly stic!y whenwet, but become hard after drying. They are neutral to slightly al!aline, rich incalcium and magnesium, moderate in potash but poor in nitrogen, phosphorus andorganic matter.

Laterite soils- These are intensely weathered soils after loss of substantial$uantity of silica during paedogenesis. The subsoil remains soft, but becomesirreversibly hard when dried and exposed to atmosphere. They are brown toyellowish-red in colour. They have good draining capacities but are low in fertility

besides poor nutrient holding capacity. %oils are acidic &mild to strong' rich in ironand aluminium oxides but poor in lime, potash and magnesium.

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Top soil"

deally, within the top si" inches or more of the soil surface,there should be a distinct layer called a hori(on? this is alsoknown as topsoil.

tFs full of living organisms, from earthworms to millions ofbenecial bacteria and fungi, that contribute to good soilhealth.

ThatFs why itFs important to routinely add organic matter to thistop layer. Grganic matter includes compost, shredded leaves,grass clippings, straw and barnyard manure.

Grganic matter is what feeds these organisms and keeps themactive, and a biologically active soil is a healthy soil.

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Su# soil"

Subsoil is the layer of soilunder the topsoilon the surface of

the ground. Dike topsoil it is composed of a variable mi"ture ofsmall particles such as sand, siltand=or clay, but it lacks theorganic matterand humuscontent of topsoil. 7elow the subsoilis the substratum, which can be residual bedrock, sediments, oraeoliandeposits. ority ofplant roots lie within the surface topsoil.

https://en.wikipedia.org/wiki/Soilhttps://en.wikipedia.org/wiki/Topsoilhttps://en.wikipedia.org/wiki/Sandhttps://en.wikipedia.org/wiki/Silthttps://en.wikipedia.org/wiki/Clayhttps://en.wikipedia.org/wiki/Organic_matterhttps://en.wikipedia.org/wiki/Humushttps://en.wikipedia.org/wiki/Bedrockhttps://en.wikipedia.org/wiki/Aeolian_processeshttps://en.wikipedia.org/wiki/Aeolian_processeshttps://en.wikipedia.org/wiki/Aeolian_processeshttps://en.wikipedia.org/wiki/Aeolian_processeshttps://en.wikipedia.org/wiki/Bedrockhttps://en.wikipedia.org/wiki/Humushttps://en.wikipedia.org/wiki/Organic_matterhttps://en.wikipedia.org/wiki/Clayhttps://en.wikipedia.org/wiki/Silthttps://en.wikipedia.org/wiki/Sandhttps://en.wikipedia.org/wiki/Topsoilhttps://en.wikipedia.org/wiki/Soil