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Do You DigWetland Soil?SummaryHow is wetland soil likea box ofcrayons?Studentsmake anduse a wetlandsoils color chart, then dig a hole ina wetland area to study thephysicalcharacteristics of the soil.

ObjectivesStudents will:• describe physical differencesbetween wetland and uplandsoils.• usekeys to recognize wetlandsoils.

MaterialsPart I:• Crayola® Crayons, 64—color boxes• scissors• paste• posterboard or manila folders• copies of the ColorMe Wet! studentpages (grades 4-12, p. 237;gradesK-3, p. 236).Part H:• clay cat litter premixed with watertomake a paste (see “How ThirstyIs the Ground?” p. 239)

• spade or narrow shovel• yard (meter) stick• pencils• hand lenses• copies of the Soils Data Chart,p. 235.

• copies ofKey to Soil Texture by Feel(for older students), p. 238.

Making ConnectionsStudents may have dugholes inthe ground and noticed variationsin soil coloration, but they maynot know what causes thesecolors, or howsoil colors areimportant for keying out soil type.In this activity, students will learnto recognize common wetland soil

types and begin to locate wetlands

in their communities.

BackgroundThere are many different typesof soils, as well as sophisticatedclassification systems to catego-rize them. Most soil types arewell-drained, nonwetlandvariet-ies. Because of the prolongedpresence of water, wetland soilsare physically differentfromnonwetland (often called upland)soils.Wetland (hydric) soils are satu-rated, flooded, or “ponded” longenoughduring the growingseason to develop anaerobicconditions in upper layers. Thatis, wetland soil is at times sosaturated withwater that itcannot holdmuch, if any, oxygen.The prolonged presence of water,and the resultant lack of oxygen,causes chemical reactions thateventually affect the color of thesoil.The study of a soil sample’s colorcan determine if it is hydric soileven if the sample is not wet atthe time of the investigation. By“reading” color charaderistics, asoil scientist can tell howlong orhow frequently an area hasbeenwet. You and your students canlearn to recognize some wetlandsoils in this manner, too.There are two major types ofwetland soils: organic andmin-eral. Organic wetland soils arethose that contain a noticeableamount (more than ten percent)of partially decomposed plantswithin at least 1.5 feet (0.46meters) of the ground’s surface.In waterlogged spots, organicmaterials accumulate. The lackof oxygen results, in a decrease in

WOW!: The Wonde,~s (~ Wetlands 231

bacterial d~omposition, andplants do not decompose as theydo in aerated situations. Wetorganic soils look like black muckor black to dark brown peat.Soils that contain little or noorganic material are classifiedas mineral soils. Mineral soilsusually consist of a wide range ofmaterials such as sand, silt, andclay. Mineral wetland soils can begleyed (pronounced “glade”) ormottled. Gleyed soils are usuallyformed when the soils are satu-rated all of the time (and thusanaerobic). These soils are usuallyneutral gray, greenish, or bluishgray.Mottled soils are formed in areasthat have wet (anaerobic) condi-tions, followed by periods of dry(aerobic) conditions. Theseconditions alternatecontinuously,possibly seasonally. The basic(matrix) soil coloroften includesconcentrated splotches of brown,orange, red, or yellow. When thesoil is very wet, minerals such asiron and manganesecollect inspaces in the soil. When air movesinto the soil during dry periods,these mineral concentrationsoxidize. The iron rusts, leavinga permanent indicator of thisprocess. Oxidized iron concentra-tions are various shades of red,orange, and yellow, while manga-nese mottles are black.When you dig a hole to studywetland soil, you may findhorizontal banding of coloredmaterials in the soil profile. Thesoil types you find will depend onthe area studied; youmaywant tocontactyour county NaturalResources Conservation Serviceoffice for expert help in identify-ing soil types. Wetland scientistsuse sophisticated tools such as theMunsell Soil Color Charts toidentify wetland soils. Each color

chip in the Munsell book repre-sents a combination of hue (color),value (lightness or darkness), andchroma (purity) that reflects thedegree of wetness in the soil. Thecolor chart developed in Part I ofthis activity is a simplified versionof the Munsell book.Keep in mind that the soils onmany properties havebeenalteredby human activities.Tilling for agriculture, filling fordevelopment, andshipping formining are afew examples ofactivities that change soils. Trytofind a relatively undisturbedsite,ifpossible. If you are lookingatsoil in a city, a suburban housingcommunity, or near farmland,you may have to dig deeper tofind undisturbed soils, includingthe original hydric soil. (Remem-ber to ask for permission to dig,and be sure you fill up holes whenyou’re done.)

Part I of this book contains otherinformation on soils (p. 12) andhelpful hints about finding wet-land studysites (see chapter 6).ProcedureWarm UpDo students have a garden orflower box athome? Have theyever noticed the color of soil?Explain that chemical reactions inwater-bearing soils cause colorchanges, and that soil color cantherefore be used as an indicatorof the frequencyand duration ofwetness. Youmight have yourmore advanced students studythese reactions. Younger studentsshould understand that thepresence of water causes chemicalchanges that makewetland soilslook different from other soils.The ActivityPart I:Make Your Own Soil ColorChart

Hand out copies of the approp~ate color chartstudent page foryour grade level and reviewthedirections. Explain that this is avery simpiffied version of theMunseil book. Have studentscolor thechart using theCrayola® Crayon colornamesgiven. (It is important to usethe indicated colors in order toidentify the soils correctly.) Havestudents complete the other stepsto prepare the charts. Theywifluse them for Part II.Part II:Dig In!

I. Before going outside, showstudents the premixed cat litter.Have each student feel themixture’s texture. Give eachstudent a copy of the SoilsData Chart studentpage.2. At the wetland, use the spadeto dig ahole abouttwo feet deepto find and study wetland soils.Note: Ifyou do not find indica-tions of wetland soils, try anotherspot.3. Avoiding the topmost layerof surface material, pick at theinside surfaces of the holewiththe end of a yardstick to revealthe true structure of the soil.Remove golfbail-sized pieces ofsoil from a side of the hole at theindicated depths (see data chart).Ask students to examine both theoutside and the inside of thesesamples (break the soil balls intotwo or threepieces).4. Have students record soilcharacteristics and observationsin the Soils Data Chart, using thecolor chart from Part I and theword lists that accompanies thedata chart. Older students canuse the Key to Soil Texture byFeel onp. 238 to identify soiltypes.Wrap Up andActionAfter thedata charts havebeen

232 © The Watercourse and Envirozunental Concern Inc. jg95

rDo You Dig Wetland Soil?

completed, use the Dig In! ques-

tions below for group discussion.

DIG IN!1. IA/hat soil characteristics did youobserve? Share data and observa-tions from students’ completedcharts. Wetland soils may haveanyof the characteristics listedbelow. If youwere able to digdown to wetland soil, the stu-dents’ charts should inone way oranothermatch these descriptions.

• some shade of darkbrown orblack (see color chart)• feels like sticky clay and is someshade of gray, green, or darkercolor (see color chart)• made up of peat or organicmaterial, sand and/or otherminerals, clay, silt, loam, or somecombination of these materials in.layers or mixtures• when squeezed, sticks togetheror oozes out of fingers in anbbonlike strand• broken surfaces of the samplesreveal mottles or splotches ofcolor throughout the sample insome shade of red,orange, oryellow (see color chart)• shades of red or orange “rusty”soil surrounding roots and rootchannels (the oxygen that wetlandplants send to their roots often“leaks” out, oxidizing the ironin the soil)• no earthworms in very wet,saturated soil (they would drownor suffocate!)• sulfur gas fromanaerobicactivity; smells like rotten eggs2. Howdid soil at the bottom of thehole differ from soil near the surface

~ in color and texture? Thisdependson the type ofwetland you werein and the level of the water tableinyour sample area. Youmay

have observed layering of soilssimilar to the diagram shownhere. Most wetland soils haveadark layer of (aerobic) organicsoilat the top, where oxygen isexchanged with the atmosphere,and (anaerobic) mineralororganic soils below.

Sample soil layersin a wetland

3. Can youfind evidence aroundyoursample area that shows where the soilparticles came from? Most organictopsoil is the result of the break-down of fallen leaves and deadplants, as described in “Nature~sRecyclers.” Organic wetland soilis the accumulation of organicmaterial that has not decayedbecause of the anaerobic soilcondition. Mineral soils areformed over time from weather-ing of rocks. Wetland soils on thebanks of streams and rivers mayhavebeen formed through thegradual deposition of soil par-ticles that were carried in (anderoded) by water.

4~ Can you tell where the water andsoils in this area are coming from?What watershed drains to this spot?Have the students look at factorsthat bringwater into the area,since it is the degree ofwetnessand how it affects the condition ofthe soil that we aremost inter-ested in here. Look at topographicfeatures of the area and weatherconditions. For example, if thewetland lies in a depression atthebottom of aslope, runoff from theslopewill end up in the wetland,eventually seeping into the soil tomake or keep it wet.5. Didyoufind anything that wasnot natural (i.e., human-made) in thesoil? How do you think it got there?In many cases, human products(e.g., litter, chemicalpollutants)enter a wetland just as depositedsoil and other natural materialsdo—with the inflow of water.These materials are introduced tothe environment at some point,whether intentionally or uninten-tionally. Discuss these possibilitieswith the class. Have studentsspeculate on the source of anyhuman-made materials they havefound.

6. Comparewetland soil to soil youhaveobserved at home andaroundschool.How do the soils differ, andwhat makes them different? Theprimary difference is thatwetlandsoil iswet or saturated for anextended period, and upland soilis not saturated. The colors of thetwo soils are different becausechemical reactions that occur inanaerobic (saturated) soils differfrom those that occur in aerobicsoils. The differences that studentsmayobserve in wetland andupland soils depend on the areassampled—thereare manypossi-bilities.Organic soils are wetlandsoils, if the overallmatrix of thesoil throughout the hole is organic.

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WOW!: The Wonders Of Wetlands 233

Assessment Notes:Have students:• observe soil samples and recordtheir observations.• classify soil types through coloranalysis.• identify environmental andhuman-made factors thatinfluence soil conditions.

ExtensionsIf you find clay or sticky soil whileoutside, have students make smallwetland sculptures to take home!Invite an extension agentor soilscientist to visit the class todiscuss the results of the fieldwork. Ask this visitor to shareaspects of his or her career withstudents.Nature in YourNeighborhood:Be a Wetland Watchdog!Axe therewetlands in yourneighborhood that need protect-ing? Find a stream or other bodyof water—or evena puddle thatstays wet for a week or more. Diga smallhole in the ground and useyour color chart to see if it may bea wetland. How arepeople usingthe land in and around this spot?Check areas wherethe groundhasbeen plowed to build a road,house, or other building. If the soilis gray or very dark, it could be awetland. Ask officials if theconstruction there is legal. Devisea neighborhood plan to make thearea even better. Youmight cleanup the area, or plant wetlandplants to prevent erosion andattract more wildlife. See chapter6 for more ideas.

234 CThe Watercourse and Environmental Concern Inc. 1995

Do You Dig Wetland Soil? Student Page

Soils Data ChartRecord the wordsor phrases that apply to each soil sample in the chart below.Texture/moisture: Rub the soilbetween your fingers. Choosewords that describehowit feels.• dry, moist, wet, verywet, or drippy• falls apart, sticks together, sticky(sticks to fingers)

• feels likeclay (easily molded intoshapes)

• slippery, oozes (extrudesbetweenfingers when yousqueeze it)

Soilparticles: Draw the size andshape of the particles. What is thesample madeof?• sand (feels gritty)• minerals (tiny bits of rock)• clay (like the cat litter sample)• silt (like flour or powder;slippery when wet)• pebbles• organic matter (bits of leaves,twigs, bark, etc.)

Colon Use color chart

Other features or creatures: Whatdoes the soil smell like? List ordescribe anyrocks, deadplants, orothernonliving materials in thesoil. List or describe anylivingthings such as worms, roots,orinsects. Do you see anyroots with“rusty” red or orange soil aroundthem?

Depth FromSoil Surface

Texture!Moisture

(describe how itfeels)

Soil Particles(describe or identify

them)

Color #(use color chart)

OtherFeatures orCreatures

2 inches (5cm)

4 inches (10 cm)

6inches (15cm)

12 inches (30 cm)

18 inches (45 cm)

I.

WOWk The Wondeis C~ Wetlands

Do You Dig Wetland Soil? Student Page (GradesK-3)

4ColorMeWet!1. Use Crayola® Crayons (a box of 64) to color in the squares on the chartbelow. It is very important to usethe right colors!

2. Fold the rectangle in half and cut out the dark circle.

3. Use your chartwhen studying soil. Yourchart is similar to the complicated color chartswetland scientistsuse to identify wetland soils.

Hold the chart inone handand holda sample of soilbehind the hole withyour other hand. Try to matchthecolor of the soil to one of the squares. If it nearlymatches a box above the diagonal line, it maybe wetlandsoil.

236 WOW!.~ The Wondea~s 0, WetLands

Do You Dig Wetland Soil? Student Page (Grades 4-12)

Color MeWet!Use Crayola@Crayons to color in the squares on the chartbelow. It is very important touse the rightcolors! Press firmlywhen coloring, unless the name says “light.” Cutout the whole chart andpaste it to a piece of posterboard or half of amanila folder. Carefullycut out the blackcircles, through all thicknesses.Use thiscolor chartwhen studyingsoil in the field. Wetland scientists use similar but muchmore complicated color chartsto identify wetland soils.Hold the chart in onehand; is the other hand hold a sample of soilbehind the chart, so that it isvisible through one of the holes. Your soil samplemay contain bits of rock, organic material, and mineral concentrations.Youmust keyoutonly the dominant soil color andignore all other materials. Move the sample arounduntil you findoneor two colors that nearly match or approximate the dominantcolor.Numbers 1, 5,6,9, 10, 13, 14, 15, 16, andsometimes 2 are probably wetland soils; the others are probably not wetlandsoils. Anysoilwith a basic (matrix) color that is a shade of dark brown,black, or gray maybe awetland soil. You willprobably see other colors andmaterials within thematrix soil-color. Thesecolorful streaks may be the result of certainminerals. Theyappear as shadesof red, orange, and yellow (associated with iron in the soil), or black (associated withmanganese,not tobe confused with darkorganicmaterial). Theseareas are good indicators of seasonalwetlands andotherwetlands that are not alwayswet. Do not use these colormottles to key out the soil,but recognizethat they arean additional indicator ofwetland conditions.

WETLAND SOILS COLOR CHARTWET DRY

10. Black+ Sepia

3. Peach 4. Goldenrod

7. Tan 8. Bittersweet

11. Olivegreen + Raw sienna 12. Indianred

13. Sea green+Gray 14. Forest green + Gray 15. Pine green+ Gray 16. Sky blue + Cornflower +Gray

1. Gray (light) +White

5.Gray

9. Black

WOW~.~ The Wonders 0, Wetlands 237

Do You Dig Wetland Soil?

Key to Soil Texture by FeelBegin atthe place marked “Start” and follow the flow chartby answering the questions, until you identify thesoil sample.

1SA

LO~ %CLAY ~HI

START —)

Is thesoil really(CLAY I neither grittyILOAMJ nor smooth?

YES NO

(CLAYJYES

WOW!: The Wonders (~Wetlands