Soil Conservation
Reading Preview
Key Concepts
• Why iI soil' v.lua~ re<olJr~1
How Can You Keep Soil From Washing Away?
• How (an soil lose in v,I",,?
1. Pour about SOO ml of soil into a pie plate, forming a pile.
• What are some ways ~I 'Oil tan
2. Deviil! a way to keoep thf! soil from washing away when water
il; poured over It. To p<ote<t the pile of soil, you may use craft
stklu, paper dips. pebbles, modeling day, strips of paper, or
other materials approll@d by your lea<her.
). After arranging your matefi,ls to protect
the soil. hold a container filled with
MC~1
Key Terms
• sod • n.;Ilm,l '''''''''fee
• Dust Sowl • ""I <~.Iion
• contour plowing
• (<>n!>efV,tion plowing
• crop rotation
~Target Reading Skill
PTttvlewing Vl~ls ~fore you
pleone-. fiqu,e 13, TM Dust
Bowl. ~ write two que!itiom
that you ... ~ about W photo and
map in;) graphic or9aniz~ like IIv
one below_ A$ you ,,,..::I, , ..........,
200 mL of water about 20 em above the
center of the soil. Slowly pour the water
in il 'Stream onto the pile of wil.
4. Compare your pan of wil with those of
your diKSinates.
.,,;HI,
Think It Over
Observing BiKed on your obse<vatiom, what do you think i" the
best w"y to prevent wil on <I 'iklpe from w<I"hing <lw;Jy"1
you< quest;"""
Suppose you were a settler traveling west in the mid 1800s.
Much of your journey would have been through vast, open
grasslands called prairies. After the forests and mountains of
the East, the prairies .....ere an amazing sight. Gr<lSs laller than a
person rippled and flowed in the wind like a sea ofgreen.
The prairie soil was very fertile, It W<lS rich with humus
bea1use of Ihe taU grass. The SO<l-the thick mass of tough
roots at the surface of the soil-kept Ihe soil in place and held
onto moisture.
'Ille prairies covered a vasl area. They indudcd Iowa and
Illinois, <IS well <IS the eastern parts of Kansas, Nebraska, and
North and South Dakota, Today, farms growing crops such as
rom, soyIx-ans, and wheat have replaced the prairies. But prairie
soils are slill among the most fertile in the world.
TMDun Bowl
Q. wt-e w •• tho! DIm Bowl?
Q.
Prairie grasH'S lind wildflowers ,.
The Value of Soil
is ;mrthing in the environment that
humarn usc. Soil is ODe of urth's most valuable natural
A
natural
.eIOWU:
ruoUI'CU because everything that livn on land, induding
humans, depends dirtctly or indirtctly on soil Planu deprod
directly on the soil to live and grow. Humans and animOlls
depend on planu.---or on other animOlls thai d~ on
plants-for food.
Fertile soil is valuable because there is a limil~ supply. Less
than one eighth of the land on Earth h.5 soils thai all' wdl
suited for farming. Soil is also in limited supply b«:ausc it 1aU$
a long time to form. It can tau hundreds of yean for just a few
centimcters of soil to form. The thick, fertile soil of me prairies
took many thousands of years to devdop.
"-II",
Duerl/
00[
..........
wtly Ii fertile soli ulu.lbl4l7
Soil Damage and Loss
Human aetiviti« and changes in the environment
,an affect lhe soil. The value of soil is redUeN when
soillosa its fC'rtiJily and when topsoil is losl due to
erosion.
loss of Fertility Soil can be- damaged when illoscs
itS r~iliIY. Soil lhal has lost its fertility is said to be
c:xh.ausled This type of soil loss occurred in large parts
of the South in UK- late- 1800s. Soils in which only
COlton had hem grown WC'J"C' ahausted Many fanTlC'rS
abitndoned lheir &rms. Earty in the- 1900s in Alabama,
a sciC'nlisl named George Washington Carva <kvd­
oprd I1C'W crops and farming mel.hods that helped 10
restore' soil feTtility in UK- South. Peanuts ~ODC' O"Op
that help«! ma1tC' the soil fertik 383in. Peanut plants
an' 1egumc-s. 1.C'gurnes ha:~ small lumps on their roots
thai umtain nitrogat-fixing bacteria. These bacteria
ma1tC' nilrogttl, an important nutrient, avaibbk in a
form that plants can USC'•
..... "
Restoring Soil Fertility
George Wmington ca.wr (186ol-1943)
wught new methods of soil ronsefV;ltlon.
He 31'iO ~~ farmen to plant
punuts, which helpo!d rtilor.:soil fertility.
Apptying Concepu ~f nutriMt do
punul ~flts MJd to fIw 'iOiIl
ChapWi" 1 G • 57
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FlGuolE 13
The Ourt Bowl
The Ourt Bowl ruiOO!d fannlaod in
western Oklahorna and parts of
the j.Urrounding stille<. Wind blew
dry part~ of soil into grut
clouds of dust that traveled
thotrsana. of kil~.. rs.
eGo -~ed:"
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for.l.ints 011 soil toII5eIY<Ilion
Visit:~org
well Code: saHl123
Loss of Topsoil Whenever soil is exposed, water and wind
can quickly erode it. Plant cover can protect soil from erosion.
PlaDIS break thl." force of fulling rain, and plant roots hold the
5Oiltogether. Wind is another cause ofsoil loss. Wind erosion is
most likely in areas where farming methods are not suited 10
dry conditions. For example, wind erosion contributed to the
Dust Bowl on the Greal Plains.
Soil Loss in the Dust Bowl Toward Ihe end of the 18OOs,
farmers .settled the Great Plains. The soil of the Greal Plains is
fertile. But rainfall decrea5C!l steadily from east to west across
the Great Plains. The region also has droughts-years when
rainfall is scarce. Plowing remo\'oo the grass from the Greal
Plains and exposed Ihe soiL In times of drought. the topsoil
quickly dried out, turned to dust, and blew away.
By 1930, almost all of the Great Plains had been turned into
fanm or ranches.. Then, a long drought turned the soil on parts
of the Great Plains to dust. The wind blew the soil east in great.
black douds that reached Chicago and New York City. The ero·
sian was most serious in the southern Plains states. This area,
shown in Figure 13, was called the Dust Bowl. The Dust Bowl
helped people appreciate the vallK" ofsoil With government sup­
port, farmers in the Great Plains and throughout the wuntry
began to take better care of their land. They adopted methods of
farming that helped save the soil. Some methods were new.
Others had been practiced for hundreds of ~rs.
;;::;a II) ~tUlused the O\m Bowl1
I
58 • G
Soil Conservation
Since the Dust Bowl, farmers have adopted modern mnhods of
soil conservation. Soil consuvation is the management of soil
to prnl:111 its destruction. Soil can ~ consen'cd through oon­
lour plowing, conserv.uion plowing, and crop rotation.
[n conlour plowing, farmers plow their fields along the
curves of a slope. This helps slow the runoff of excess rainfaU
and prevents it from washing the soil away.
In ron5eO'lluon plowing. farmers disturb the soil and ilS
plam 00\'n" il$little as possible. Dead weeds and stalks of the pre­
vious )nT'S crop are left in the ground to hdp mum soil nUln­
nilS, relain moisrurt', and hold soil in plxe. This mrthod is also
called low-till or no-till plowing.
[n crop rotation, a farmer plants different
.......
Soil Comentltion Mdhods
ThiJ ,......'s roelch $how .... <knc:..
of contour plowing and aop
rotation. PNdicling Howmighr
COOlOlH" pIowing.fff'd rhf'
a..-nlt of topsoil?
crops in a field t"ach yl"ar. [)ifT~t typtS of plants
absorb different amounu of nutric:nl$ from tht
soiL Some crops, such as com and C()(IOn, absorb
large amounts of nutrients. The year aftC'T plant.
ing tht= crops, the farmer planu crops that use
fewer soil nutrients, such as oats, barley, or !")T.
The year after that the farmer soW!; leguntn such
as alfalfa or beam; 10 restore the nulrienl mpply.
S.,t;on
3 Assessment
~ Target Reading Skill " .......,,;ng VI5UIIk Com~ J'UUI"
qUf'$tions and &nSWftS aboul F'KW" 13 with thosf' of a p;utncr.
Reviewing Key Concepts
1. I. Defining Wltal is a natural rt'SOuJU?
b. fxp!.inlng Wlty is wi! valuabk as a 1lI1ura.ll'f'SOl1lU'?
2.•. lkting Whal a", IWO wa~ in which the value of soil
can be rf'dUCl'd?
b. bplalning &pla.in Itow lopsoil em be 101;1.
t. Regling c.UH and EtfKt What caused the Dust fk-I?
3. a. Defining Wltal is soil CQnKrVation?
b. Lktlng Whal a", Ihl'ff methods by which fnmen can
CQIlS('rvt'soil!
t. ',obIem Solving A fanner gruwing com w:rnu to
maintain lOiI fmilily and rf'duu f'1ll$oo. Whal
conservation methods muld the farmf'l" try? Explain.
Pet.
I, .ell Ai.
I
,wit
A ~ drought in • fanning
region thrNtenI to produce
.,oOdwr D\at Bowl. Write •
~aph about soillOl_ • .tlon
to be read '" • public .....ice
.nnoun<ement on .-.die> stMionI
1'he'~1houId• •!ify
the dM'Igef of soil _ due to
lIfosiort. It should also ditto !be the
1tep5 far'mIn c. tIIke to CUflSlirw
the soil.
Chapbor:J: G. 59