kry495
“Understanding Soil Erosion”
Introduction
Over Thanksgiving break, my family and I went to Las Vegas. Onthistrip,wevisited
differentplacessuchasTheGrandCanyon,TheBryceCanyon,andtheZionCanyon.Thetourist
guide told us that the formation of these canyons could be attributed to sand erosion. I was
amazed by the shapes, colors, and vegetation these canyons produced. Therefore, Idecidedto
create an experiment focused on erosion but on a small scale. By creating a controlled
environment, the “Understanding Soil Erosion” experiment investigatestheimpactofdifferent
soil compositions on the volume of water collected as it filtrates through the soil.
It is essential to mention that I designed this experiment's methodology to replicate
real-world circumstances: a wooden board functioned as a slope simulator, replicating an
inclination.Atthesametime,awateringcanserveasarainsimulator.Thissetupalsoallowsme
to understand which abiotic factor helps absorb water quicker, retain it, or let it drain
away—creating a clearandstraightforwardwayinwhichthegivenresultsgivemeinsightinto
how soil components can impact water availability in an environment.
Background Information
Soil is a complex material composed ofminerals,water,air,andnutrientparticles.Soil
alsoconsistsofsmallpiecesofbrokenrockanddecayingplantscalledorganicmatter.Thesmall
rock-like particlesthatmakeupsoilcomefromlargerrocks.Overtime,rainandotherweather
events cause small particles to break loose from the larger rocks. All these particles, in
combination with organic matter, form soil. (ErosionLab)
Soil erosion is the natural process in which wind, ice, waves, glaciers, water, and/or
gravity move soil particles from one location to another by detaching and transporting them
down a slope (a landscape or surface tilted or inclined.) Erosion can occur at different rates
depending on the land'stopography(thearrangementofanarea'snaturalandartificialphysical
features). Someofthemainfactorsthataffecttherateofsoilerosionincludeslope,vegetation,
and rainfall.
Theslopeofthelandplaysacrucialroleinsoilerosion.Thesteepertheslope,thegreater
thevelocityofthewaterflowingacrossthesurfaceanditscapacitytotransportanderodesoil.In
addition,iftheslopelengthincreases,thewater'serosiveenergyalsoincreases(IUPUISchoolof
Science).
Soil components also influence erosion rates. For example, biotic factors such as
vegetation arecriticaltocontrolerosion.Vegetativecoveractsasabarrierthatprotectsthesoil
particles from the impact of raindrops. Having leaf cover from trees and organic waste on a
forest floor can reduce the effect of soil erosion caused by raindrops. Conversely, a higher
concentration of abiotic elements, such as rocks and dry leaves, can enlarge thegapsbetween
soil particles, potentially facilitating the acceleration of soil erosion due to increased water
runoff.
Furthermore,themainbioticfactorthataffectserosionisrainfall,whichconsistsoftwo
factors: the amount ofrainthatfallsanditsintensity.Inthiscase,theterm"intensity"refersto
therateatwhichrainisdeliveredtothesoilsurface.Highintensitycausessoilparticlestodetach
and wash away more easily and frequently, increasing the soil erosion rate. These factors
determine theamountoferosionthatwilloccurandtheamountofsoilthatmaybetransported
and deposited elsewhere.
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, Humans have dramatically accelerated erosion through agricultural practices, mining,
logging,andclearingandgradingforconstruction.Theseactivitiescancausedetrimentaleffects
on the environment, degrading water quality, compacting the soil, limiting water infiltration,
removing vegetation, and exposing the soil surface, increasing both runoff and erosion. These
humanactivitieswillincreaseerosionbecausetheydisturbthenaturalsoilstructure,makingthe
soil more susceptible to wind and water carrying it away. In addition, these activities usually
remove the protective cover of the soil, leaving it exposed to rain, wind, and other natural
factors. For example, talking about agricultural practices, when the soil contains harmful
pesticides (artificialchemicalstocontrolweedsandinsects),theycanbecarriedbylandrunoff
and eventuallypollutethewaterwayshumansrelyonfordrinking.Moresoilerosioncanoccur
where the land could be better managed, leading to better water quality.
Erosion rates are higher on landsdenudedandreshapedforurbandevelopmentthanon
agricultural land.Plantscanactasshieldsagainstsoil.Therefore,plantshelpalotbysoftening
thehitofrainontheground,whichleadstolesssoilerosion.Butwhenhumansbuildcities,they
oftenhavetoclearawayalltheplants.Thisleavesthegroundbareandmorelikelytobeeroded
quickly by rain and wind. Additionally, soil erosion reducesagriculturallands'productivityby
removing topsoil and exposing less desirable subsoil. This resultsinlosingorganicmatterand
nutrients, reducing fertility and plant-available water-holding capacity.
The idea behind this experiment is to create a small-scale simulation to explore the
dynamics of soil erosion since the main factors that affect soil erosion are slope, biotic and
abiotic factors, and rainfall. Watercress (N asturtium officinale) and succulents (Aeonium
haworthii) will be used for biotic factors. In contrast, rocks and dry leaves will be used for
abiotic factors, and onecontrolgroupwithjustsoilwillbeadded.Inaddition,awoodenboard
will function as a slope simulator while the water used for watering the different categorical
variables will simulate rainfall. For instance, and asmentionedbefore,vegetativeelementsare
expectedtoretainmorewater,exposingtheirnaturalfunctionofplantlifeinerosionprevention.
Ontheotherhand,abioticcomponentssuchasrocksanddryleavestypicallydonotretainwater
as effectively as biotic materials.
esearch question
R
Howdoessoilcontent(rocks,dryleaves,watercress,succulents,andstandardsoilasacontrol)
affect thevolumeofwater(mL)collectedasitfiltratesthroughthesoilandismeasuredwitha
100mL measuring cylinder?
Hypothesis
Null Hypothesis (H0): There is no statistically significantcorrelationbetweensoilcontenttype
(bioticfactorslikewatercressandsucculentsandabioticfactorslikesoil,rocks,anddryleaves)
and the volume of water (mL) that filtrates through the soil.
Alternative Hypothesis (H1): The volume of water (mL) that filtrates through the soil is
statistically significantly different depending on the soil content type (biotic factors like
watercress and succulents and abiotic factors like soil, rocks, and dry leaves).
Bioticfactorssuchasplantscanretainwaterandnutrientsintheirroots,whicharevital
for their growth and survival. As a consequence, watercress and succulents are expected to
absorbmorewater.Incontrast,abioticfactorsarelesslikelytoretainwaterbecausetheylackthe
internal mechanisms necessary for water retention.
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