agriculture food animals

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NATURAL RESOURCES

Agriculture


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Agriculture

Animals

Energy

Forests

Lands

Minerals

Plants

Water and Atmosphere

NATURAL RESOURCES


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AGRICULTUREThe Food We Grow and Animals We Rais

Julie Kerr Casper, Ph.D.


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Agriculture

Copyright2007byJulieKerrCasper,Ph.D.

Allrightsreserved.Nopartofthisbookmaybereproducedorutilizedinanyformorbyanymeans,

electronicormechanical,includingphotocopying,recording,orbyanyinformationstorageor

retrievalsystems,withoutpermissioninwritingfromthepublisher.Forinformation,contact:

ChelseaHouse

AnimprintofInfobasePublishing

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ISBN-10:0-8160-6352-4ISBN-13:978-0-8160-6352-9

Library of Congress Cataloging-in-Publication Data

Casper,JulieKerr.

Agriculture:thefoodwegrowandanimalsweraise/JulieKerr

Casper.

p.cm.(Naturalresources)

Includesbibliographicalreferencesandindex.

ISBN0-8160-6352-4(hardcover)

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1

1

1

Concepts of Agriculture

The History of American FarmingRenewable and Nonrenewable Resources

Development of Agricultural Diversity

Use of the Land and Agricultural Diversity

The Importance of Agriculture

Management of the Land, Water, Soil, and

Environment

Conservation of Agricultural Resources

Conclusion: Future Issues and Land Stewardship

Preface

Acknowledgments

Introduction

Chronology

Glossary

Further Reading

Index

1

2

3

4

5

6

7

8

9

1

1

2

2

Contents


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Mankind did not weave the web of life.

We are but one strand in it. Whatever we

do to the web, we do to ourselves . . .

All things are bound together.

ChiefSeattle

Natural Resources:

Priceless Gifts from the Earth

Preface

vi

TheEarthhasbeenblessedwithanabundantsupplyofnatural

resources.Naturalresourcesarethoseelementsthatexiston

theplanetfortheuseandbenefitofalllivingthings.Scien-

tistscommonlydividethemintodistinctgroupsforthepurposesof

studyingthem.Thesegroupsincludeagriculturalresources,plants,

animals,energysources,landscapes,forests,minerals,andwaterandatmosphericresources.

Onethingwehumanshavelearnedisthatmanyoftheimportant

resourceswehavecometodependonarenotrenewable.Nonrenewable

meansthatoncearesourceisdepleteditisgoneforever.Thefossil

fuelthatgasolineisproducedfromisanexampleofanonrenewable

resource.Thereisonlya finitesupply,andonceitisusedup,that is

theendofit.

While living things such as animals are typically considered

renewable resources, meaning they can potentially be replenished,animalshuntedtoextinctionbecomenonrenewableresources.Aswe

knowfrompastevidence,theextinctionsofthedinosaurs,thewoolly

mammoth, and the saber-toothed tiger were complete. Sometimes,

extinctionslikethismaybecausedbynaturalfactors,suchasclimate


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PREFACE

change, drought, or flood, butmany extinctions are caused by the

activitiesofhumans.

Overhuntingcausedtheextinctionofthepassengerpigeon,which

was once plentiful throughout North America. The bald eagle washuntedtothebrinkofextinctionbeforeitbecameaprotectedspecies,

andAfricanelephantsarecurrentlythreatenedwithextinctionbecause

theyarestillbeinghuntedfortheirivorytusks.Overhuntingisonly

onepotentialthreat,though.Humansarealsoresponsibleforhabitat

loss.Whenhumanschangelanduseandconvertananimalshabitat

toacity,thisdestroystheanimalslivingspaceandfoodsourcesand

promotesitsendangerment.

Plantscanalsobeendangeredorbecomeextinct.Animportant

issue facing us today is the destructionof the Earths tropical rain

forests.Scientistsbelievetheremaybemedicinalvalueinmanyplant

speciesthathavenotbeendiscoveredyet.Therefore,destroyingaplant

speciescouldbedestroyingamedicalbenefitforthefuture.

BecauseofhumanimpactandinfluenceallaroundtheEarth,it

isimportant tounderstandournaturalresources,protect them,use

themwisely,andplanforfuturegenerations.Theenvironmentland,

soil,water,plants,minerals,andanimalsisamarvelouslycomplex

anddynamicsystemthatoftenchangesinwaystoosubtletoperceive.Today,wehaveenlargedourvisionofthelandscapewithwhichwe

interact.Farmersmanagelargerunitsofland,whichmakestheirjob

morecomplex.Peopletravelgreaterdistancesmorefrequently.Even

whentheystayathome,theyexperienceandaffectalargershareof

theworldthrough electroniccommunicationsandeconomicactivi-

tiesandnaturalresourceshavemadetheseadvancementspossible.

The pace of change inour societyhas acceleratedaswell. New

technologies are always being developed. Many people no longer

spendalltheirtimefocusedinoneplaceorusingthingsintraditionalways.Peoplenowmovefromoneplacetoanotherandareconstantly

developingandusingnewanddifferentresources.

Asustainablesocietyrequiresasustainableenvironment.Because

ofthis,wemustthinkofnaturalresourcesinnewways.Today,more


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AGRiCuLTuREviii

thanever,wemustdedicateoureffortstoconservetheland.Westilllive

inabeautiful,largelynaturalworld,butthatworldisquicklychanging.

Worldpopulationgrowthandourdesiretolivecomfortablyareexert-

ingpressuresonoursoil,air,water,andothernaturalresources.Aswedestroyandfragmentnaturalhabitats,wecontinuetopushnonhuman

life intoever-smallerpockets.Today,werun the riskof thoseplaces

becomingisolatedislandsonadomesticatedlandscape.

In order to beresponsible caretakers of the planet, it is impor-

tanttorealizethatwehumanshaveapartnershipwiththeEarthand

the other life that shares the planet with us.This series presents a

refreshingandinformativewaytoviewtheEarthsnaturalresources.

Agriculture: The Food We Grow and Animals We Raiselooksatagri-

culturalresourcestoseehowresponsibleconservation,suchascaring

forthesoil,willgiveuscontinuedfoodtofeedgrowingpopulations.

Plants: Life From the Earthexaminesthemultitudeofplantsthatexist

andtheroletheyplayinbiodiversity.Theuseofplantsinmedicines

andinotherproductsthatpeopleuseeverydayisalsocovered.

InAnimals: Creatures That Roam the Planet,theseriesfocuseson

thediversespeciesofanimalsthatliveontheplanet,includingthe

importantrolestheyhaveplayedintheadvancementofcivilization.

Thisbookintheseriesalsolooksathabitatdestruction,exoticspecies,animalsthatareconsideredindangerofextinction,andhowpeople

canhelptokeeptheenvironmentintact.

Next,inEnergy: Powering the Past, Present, and Future,theseries

explorestheEarthsenergyresourcessuchasrenewablepowerfrom

water,oceanenergy,solarenergy,windenergy,andbiofuels;andnon-

renewablesourcesfromoilshale,tarsands,andfossilfuels.Inaddi-

tion,thefutureofenergyandhigh-techinventionsonthehorizonare

alsoexplored.

InLands: Taming the Wilds,theseriesaddressesthelandandhowcivilizationshavebeenabletotamedeserts,mountains,arcticregions,

forests,wetlands, and floodplains. The effects that our actions can

haveonthelandscapeforyearstocomearealsoexplored.InForests:

More Than Just Trees,theseriesexaminestheEarthsforestedareasand


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PREFACE

howuniqueandimportanttheseareasaretomedicine,construction,

recreation, and commercial products. The effects of deforestation,

pestoutbreaks,andwildfiresandhowthesecanimpactpeoplefor

generationstocomearealsoaddressed.In Minerals: Gifts From the Earth,thebountyofmineralsinthe

Earthandthediscoveriesscientistshavemadeaboutthemareexam-

ined.Moreover,thisbookintheseriesgivesanoverviewofthecritical

partmineralsplayinmanycommonactivitiesandhowtheyaffectour

liveseveryday.

Finally,inWater and Atmosphere: The Lifeblood of Natural Systems,

theserieslooksatwaterandatmosphericresourcestofindoutjust

how these resources are the lifeblood of the natural systemfrom

drinkingwater,foodproduction,andnutrientstoragetorecreational

values.Drought,sea-levelrise,soilmanagement,coastaldevelopment,

theeffectsofair andwaterpollution,anddeep-seaexplorationand

whatitholdsforthefuturearealsoexplored.

Thereaderwilllearnthewisdomofrecycling,reducing,andreusing

ournaturalresources,aswellasdiscovermanysimplethingsthatcanbe

donetoprotecttheenvironment.Practicalapproachessuchasnotleav-

ingthewaterrunningwhilebrushingyourteeth,turningthelightsoff

whenleavingaroom,usingreusableclothbagstotransportgroceries,buildingabackyardwildliferefuge,plantingatree,formingacarpool,

orstartingalocalneighborhoodrecyclingprogramareallexplored.

Everybody is somebodys neighbor, and shared responsibility is

thekeytoahealthyenvironment.Thecheapestandmosteffective

conservationcomes fromworkingwithnature. This seriespresents

thingsthatpeoplecandofortheenvironmentnowandtheimportant

roleweallcanplayforthefuture.AsawiseNative-Americansaying

goes,WedonotinherittheEarthfromourancestorsweborrowit

fromourchildren.


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Acknowledgments

x

While the fruits of farming are everyones business, hardly

anyone in theUnitedStates is in the business of farming

today.Thereisnoothercountrywhosepeoplearefreerfrom

thetoilofhavingtoraisetheirownfood.Thereisnosupplyintheworld

thatismoreabundant,affordable,orsafethanintheUnitedStates.

Ihopetoinstillinyou,thereader,anunderstandingandapprecia-

tionoffarminglife.Farmersareourunrecognizedheroes.Farmingis

hardwork,andweoweoursurvivaltoallthededicated,hardwork-

ingpeopleinvolvedintheproductionofagriculture.Inordertofully

appreciatetheirefforts,itisnecessarytounderstandwherefoodcomes

from,whatittakestogetittothegrocerystore,andhowmuchofa

bargainittrulyis.

IwouldliketothanktheUnitedStatesDepartmentofAgriculture

(USDA);theAgriculturalResearchService(ARS);theCooperativeStateResearch,Education,andExtensionService(CSREES);theEconomic

ResearchService(ERS);andtheNationalAgriculturalStatisticsService

(NASS) for their constantefforts toward improving the standardof

livingofthepeopleoftheworldandforthebountyofinformation

theymakeavailableforustolearnfrom.Iwouldalsoliketoextend

specialthankstoDebraSpielmaker,coordinatorfortheAgriculturein

theClassroomprogrambasedatUtahStateUniversity,forherhelpful

suggestionsandguidanceduringtheresearchforthisbook.


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introducton

xi

One of the most important uses of the lands natural

resourcesisfortheproductionofagriculture.Weallneed

toeat,andthecultivationofagricultureaffectseveryone

onEarth.Ourconnectiontoagricultureiscleareverytimewebuya

loafofbread,pickanapple,oreatasliceofpizza.

People all over the world must farm, and certain parts of the

worldareusedforgrowingcertaincropsorraisingcertainanimals.

For example, tropical locations are needed to grow products like

pineapple, sugarcane, andmango.Countries inSouthAmerica are

known for raising beef cattle. America produces vast amounts of

wheatandgrain.Asiasclimateiswellsuitedforproducingrice.

Americasagriculturalproductionistheenvyoftheworld.The

UnitedStateshasanabundanceoffertilesoilandgoodclimatesin

whichtogrowfood.Ourfarmersandranchersproducesafe,afford-ablegrainforhumans;feedgrainsforanimals;meatanddairyprod-

ucts;fruitsandvegetables;andfibercrops.

Evenwiththegrowthofourcitiesandthespreadoftownsand

industrialdevelopmentacrossthecountry,theUnitedStatesisstillan

agriculturalnation.Fiftypercentofthecountry(907millionacres)

is cropland, pastureland, and rangeland on privately owned land.

ThismeansthatthecareofhalfoftheUnitedStatesisinthehands

ofonly2%ofourpopulation.Becauseofthis,itisimportantthat

weallunderstandbasicconceptsofconservationandlandsteward-shiptheconceptthateverybodyissomebodysneighborandthat

howwe care for the land affectsmuch more than we may realize.

EventhoughtheprivatelandinAmericaproducesanabundanceof

food,the landalso representsmany rich, diverseplaces fullof life.


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AGRiCuLTuRExii

Whenthoseplacesarehealthy,theyhelpsupporttheexistenceofall

creaturesonEarth.

FarmsandranchesintheUnitedStatesproducemuchmorethan

food. Well-managed agricultural land also produces healthy soil,cleanairandwater,wildlifehabitats,andbeautifullandscapesall

ofwhicharevaluedbypeoplewholiveinrural(farming)andurban

(city)areas.

Alotofthought,work,andconservationarerequiredforsuc-

cessful agriculture.Healthy, productive landdoesnot just happen.

Scientistsknowfarmerscanproduceabundantfoodwithoutruining

theEarth.Infact,environmentallyfriendlyfarmingcanhelppreserve

thesystemthatconnectshumankindwitheverythingelse.

Farmers, ranchers, and other landowners have not solved all

conservationproblems,however.Soilerosionstillruinssomeland,

makingitinfertile(nonproductive).Thecontinuinggrowthoftowns

andcitiescreatescompetitionforwaterthatwaspreviouslyusedfor

farming.Agricultureinsomeareashashurtbiodiversity.Thequality

ofdrinkingwaterisalsoaprobleminsomeareasduetopollution

fromchemicalsusedtoincreasesoilfertilityinordertogrowmore

crops,orfromsedimentsfromsoilerosion.

Weareverylucky,though,toliveinatimeofadvancedtechnol-ogy.Newdiscoveriesandfarmingtechniquescontinuallymakeagri-

culturemoreproductive,efficient,and friendlyto theenvironment.

Conservationtoolsthatprotectthesoilandnewtoolsthatincrease

theefficiencyoffertilizers,pesticides,herbicides,andirrigationwater

nowexist.

Workingwiththelandinordertoprotectitthroughtheuseof

grassedwaterwaysandriparian(water-related)buffersandbyrestor-

ing streamchannels, for examplehasopened upaworldof new

possibilitiesforpracticingconservationeveryday.Agriculturalresourceconcernsaredifferenttodaythantheywere

75yearsagointhiscountry,soscientistsaskdifferentquestionsand

developdifferent techniques.We are fortunate tohave thebenefits

ofmoderntechnologytoguideus.Inthefuture,ourgrandchildren


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iNTRoduCTioN

mayaskquestionsthatwehavenoteventhoughtof;theymayuse

technologieswecanonlyimagine.Thatiswhycontinuedlearningof

agriculturalissuesissoimportantinourcomplexlandscape.

Thisbookaboutagriculturelooksatthedevelopmentoffarming,wheretheagriculturalareasoftheworldarelocated,andhowagricul-

turehasshapedcivilizationovertime.Itrevealshowafarmworksand

howfarmersmanagetofeedtheworld,whysoilsandclimateareimpor-

tant,andhowweedscanbeathreattoagriculture.Theconceptofland

stewardshipandhoweveryonesharesapartinitssuccessisexplored.

Typesofrenewableandnonrenewableresourcesareaddressed,as

wellastheconceptofsustainableagriculture.Agriculturaldiversity

andalternativefarmingtechniquessuchasaquaculture,hydropon-

ics,organicfarming,community-basedfarming,andagroforestry

arepresented.

Thisbookexploresissuesrelatedtowhymanagingtheland,water,

andsoilisabalancingactandwhyitissocritical;andwhyrecycling,

reducing, and reusing are concepts that affect everyonenow and

into the future. Finally, it explores the future of agriculture: new

technologyanddevelopments,syntheticmaterials,howtheU.S.space

programiscurrentlyplayingaroleinstudiesconcerningagricultural

issues,andhowagriculturecanbeusedtocreatefuelandenergyanexcitingconceptcalledbiofuel technology.


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A

griculture is the process of producing food, including grains,

fiber,fruits,andvegetables,aswellasfeedforanimals.Italso

includesraisinglivestockdomesticatedanimalssuchascows.Besidesfoodforhumansandanimalfeeds,agricultureproducesgoods,

suchasflowers,nurseryplants,timber,leather,fertilizers,fibers(such

ascottonandwool),fuels(suchasbiodiesel),anddrugs(suchasaspirin,

sulfa,andpenicillin).

IntheWesternworld,suchasintheUnitedStates,theuseofgenetics

andbetternutrientshavemadefarmingthelandmuchmoreproductive.

Ouradvancedtechnologyhasmadeitpossibleforfewerpeopletoneedto

spendtimefarming.Inthethirdworld,wherecountriesarestilldevelop-

ingandarenotasproductive,itisnecessaryformostpeopletobefarmersbecausetheyneedtoraiseorgrowtheirownfood.

Modernagriculturedependsheavilyonengineeringandtechnology.

Thebiologicalandphysicalsciencescontinuetoplayacriticalroleand

willbecomeevenmoreimportantinthefuture,aspopulationscontinue

COnCepTs Of

AgriCulTure

CHAPTER

1


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AGRiCuLTuRE

togrowandotherdemandsaremadeontheland.Thischapterexamines

thedevelopmentoffarming,theimportanceofclimateandsoil,howa

farmworks,thestrugglewithinvasiveweeds,andtheconceptofhealthy

land stewardship.

The evoluTion of farming

With the inventionof agriculture inabout 10,000b.c.,human beings

begantotakecontrol of theirenvironment.They replaced the natural

vegetationwithcrops sothat theycouldhave adependable food sup-

plyinordertosurvive.Upuntilthattime,peoplewerehunter-gather-

ers,whohadtospendmostoftheirtimegatheringwildseedsandfruit,

and hunting animals. Fortunately, people began to realize that crops

could be planted and grown, and animals could be tamed to assist

inplowing.

Archaeologists (scientists who study past civilizations) think agri-

culturemay alsohave started forsocial reasonsso that people could

harvestandtradewitheachother.Whatevertheexactreason,therewasa

gradualtransitionfromahunter-gathererlifestyletoanagriculturalone,

wherespecificcropswereplantedatspecifictimesoftheyear.

Farmingbeganinatleastfivedifferentplaces.PeopleinTurkeyand

theMiddleEastbegancultivatingwheat,barley,peas,andlentils.Theyalsobeganraisingsheep andgoats. InSoutheastAsia,peoplebeganto

growvegetablesandraisepigsandchickens.InSouthAmerica,separate

agriculturaldevelopmentbeganintheAndesandtheAmazonregions.

PeoplelivinginnorthernChinaandWestAfricaalsobegantheirown

developmentofagriculture.

The earliest kind of plowcalled anardthat farmers usedwas

crudelyconstructedoftimber,anditjustloosenedthesoil.Earlyfarmers

alsouseddiggingsticks,thehoe,andthescythe.Inaddition,theycreated

ingenioussystemsofirrigationtocontrolwatersupply.Thefirstsignifi-cantdevelopment,whichhappenedarounda.d.1000,wasthemoldboard

plow.Thisplowloosenedthesoil,turneditover,andburiedtheweeds,

leavingthegroundreadytoplant.Moldboardplowsarestillusedinmany

partsoftheworldtodayandarepulledbyanimals.


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CoNCEPTs oF AGRiCuLTuRE

Originally,inabout3500b.c.,oxen(cattleusedforpullingequipment)

wereusedtopullprimitiveplows.Lateron,inEurope,thehorseshoeand

horsecollarwereinvented,andovertime,manyfarmerschangedtoheavy

horses,which couldmove faster than oxen. Later, inother developingareas,wheelsandaseatwereeventuallyaddedtotheplow.Metalparts

werethenadded,whichimprovedtheplowsefficiency.

InthewesternplainsoftheUnitedStates,usingthetraditionalmold-

boardplowdidnotworkwellbecauseitwashardto cut through the

densegrassandkeepthedirtfromstickingtotheplow.In1847,John

Deereinventedabladethatwasself-polishingandworkedwellinthe

grasslandsoftheUnitedStates.Thatwashowthewell-knownJohnDeere

Companybegan.Today,itisacriticalpartofagricultureandmakeshigh-

techequipmentformanyaspectsoffarming.

how agriculTure has changed civilizaTion

Whenpeoplewere living the hunter-gatherer lifestyle, the land could

onlysupportalimitednumberofpeople.Oncecropscouldbegrown,

harvested,andstored,allthatchanged.Theadvantagesofbeginningan

agriculturalsocietywerethatalargerpopulationcouldbesupportedand

thechancesofsurvivalwereenhancedbybeingabletostoreexcessfood

overthewinter.Agriculturealsoallowedpeopletostayinoneplaceandnothavetomovearoundtogatherfood.Itpromotedcommerce(busi-

nessandtrading)betweencivilizations,whichwereabletosellgoodsand

makemoney.Thisbegantheearlystagesofmodernizingtheworld.

Allthemajorcentersofagriculturebeganalongmajorriversystems.

Without rivers like theNile, theIndus, theHuang, theTigris, andthe

Euphratestoprovideaconsistentsourceofsilt(anaturalfertilizer)from

yearly floods, and water for irrigating crops, agricultural development

couldnothavetakenplace.Itwasalsoduringthistimethatthefarmers

oftheFarEastrealizedtheycouldgrowriceonfloodedfields.Asfarmingbecamemore sophisticated,fewerpeopleneededtobe

farmers.This freedothers topursue scientific, industrial, and cultural

paths, which led to many new inventions. This shift made possible

developmentsinarchitecture,includingthebuildingofthehugepalaces,


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AGRiCuLTuRE

temples,andtheatersforwhichmanyfamousancientsitesareknown.

Take, for example, themajestic pyramids of Egypt and the beautiful

temples in Greece. Advances in agriculture allowed other people to

becomescientistsandstudyastronomy,whichbeganthedevelopmentof

navigationalskillsthatwerelaterusedtoexploretheworld.Noneofthe

majorhumandevelopmentsthroughhistorywouldhavebeenpossibleifagriculturehadnotbeendeveloped.Farmingledtoafoodsurplusthat

couldsupportartists,builders,priests,philosophers,andscientists.

InU.S.history,thesugarmillandEliWhitneyscottonginhelped

tosupportthesystemof largeplantationsbasedonasinglecrop.Later,

In this photograph taken in 1940, a farmer in Iowa operates a plow and

harrow with a team of horses. The use of horses for plowing today is rare

in the United States. (Courtesy of the U.S. Department of Agriculture; photoby John Vachon)


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theIndustrialRevolutioninthelateeighteenthcenturycausedtherapid

growthoftownsandcitiesandforcedagriculturetobeisolatedwithinits

ownarea.Asinventionslikethecultivator,reaper,thresher,and combine

appeared,modernagriculturefurtheradvanced.Theseadvancesenabledlarge-scale agriculture to develop.Modern science also revolutionized

foodprocessing,suchaswiththeinventionofrefrigeration.Today,har-

vestingoperationshavebeenmechanizedforalmosteveryplantproduct.

Breedingprogramshavemadelivestockproductionmoreefficient,too.

Geneticengineeringhasrevolutionizedgrowingcropsandraisinglive-

stock.Agriculturehasplayedasignificantroleinallowingpeopletohave

thelifestylesandfreedomstheyenjoytoday.

differenT agriculTural meThods

for differenT environmenTs

Farmingisnotthesameallaroundtheworld.Becauseclimate,soil,and

rainfallvaryfromregiontoregion,differentfarmingmethodsworkbet-

terfordifferentplaces.Inaddition,certainareasoftheworldarebetter

forgrowingcertaintypesofcrops.Somefarmsarehuge,whileothers

aresmall.Someareoperatedbylargecompanies,othersbyindividual

families. Some farmsaremodern;others are the sameas theywere a

long,longtimeago.Nomatterwhatsizeortypeoffarmitis,farmingishardwork.

In theUnitedStates, there aremany typesof farms, such as dairy

farms;grainandcerealfarms;ranchesthatraisebeef cattle;fruitorchards;

cotton, tobacco, and tea plantations; and vegetable farms. TheUnited

Statesisfortunatetohavemodernequipment,electricity,adequateroads

totransportgoods,andefficientmarketsinwhichtosellgoods.

InAsia,riceisanimportantcrop.Farmersmayliveinsmallvillages

nexttoricepaddies.Manyofthesefarmersuseanimals,suchaswater

buffalo,topulltheirplows,tohelpwithharvesting,andtotransporttherice tomarket.Russiaiswell knownasaproducerofwheat.Australia

andNewZealandareknown for sheep ranching.Sheepare raised for

theirwoolandmeat.Ranchersusesheepdogstoherdandkeeptrackof

theirflocks.AfarminIsraeliscalledakibbutz.Manypeopleliveonthe



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AGRiCuLTuRE

kibbutzandshareinthework.BecauseIsraelishotanddry,thesefarm-

ershavetoterracethehills,planttrees,digirrigationcanals,andfertilize

thesoil.Thesefarmsarewellknowntodayforthelargevarietyoffruits

andvegetablesthattheyproduce.InSwitzerland,whereitisverymoun-tainous, farmersraise goats andcows.Manyaredairyfarmers,whose

farmsproducemilkandcheese.InFrance,theclimateiswellsuitedfor

growingfruitsandvegetables.Franceisfamousforitsfertilevineyards

wheregrapesaregrown,whicharelatermadeintowine.InHolland,the

farmlandliesbelowsealevel.Dutchfarmersusepumpsandwindmills

tokeepthefertilegrounddryenoughtofarm.Hollandisfamousforits

dairyproducts,flowers,andvegetables.

InAfrica,wherethereisatropicalclimate,farmersgrowbananason

hugeplantations.Thefarmersmustpickthebananaswhiletheyarestill

greenbecausethebananasmustbecarriedbymuleorrailroadandthen

putonboatstobeshippedtootherlands.

ThecountryofBrazil,inSouthAmerica,isfamousforgrowingcof-

fee.Thefarmerstheremustpickthecoffeebeans;shellthebean;and

thendry,sort,andbagthebeansbeforetheycanbeexportedtoother

placesaroundtheworld.InArgentina,wheretherearehuge,broadgrass-

lands,thefarmersareactuallyrancherswhoraisebeefcattle.

Nomatterwhatkindoffarmafarmerhas,heorshemusttakecareoftheland.Farmersmustkeepthesoilfertile,irrigatethecrops,plantthe

bestseeds,andraisestronganimals.Themorethattechnologyadvances

andpeoplelearnhowtoworkwiththeenvironmentinsteadofagainstit,

themoresuccessfulandproductiveagriculturewillbeforfeedinggrow-

ingpopulations.

Agricultureisthescienceandpracticeofproducingcropsandlive-

stockfromthenaturalresourcesoftheEarth.Theprimaryaimofagri-

cultureistohavethelandproduceabundantlyand,atthesametime,to

protectitfromdeteriorationandmisuse.Inordertobetterunderstandtheconcept of agriculture, thinkof thefive Fs: farming, food, fiber,

forestry,andflowers.

Farming is the actual production of food and fiber derived from

plantsand animals.Farmers usemany natural resources, such as soil,


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This diagram illustrates what the surface of the Earth is used for. Ocean

water covers 75%; desert/swamps/mountains/polar regions cover 12%;rocky land with poor soil covers 3%; land areas that are too wet to cultivate

cover 3%; land surfaces that are too hot to cultivate cover 3%; land used

for urban development is 3%; and land whose soil is suited for agricultural

production is about 1%. (Source: U.S. Department of Agriculture)

sunshine,water,andair.Farmingisascience,butfarmingisalsoabusi-

ness.Itisasciencebecausefarmersmustknowaboutsoil,water,weather,chemistry,biology,andecosystems.Itisabusinessbecausefarmersmust

knowabouteconomics,business,andtrade.

Foodistheproductthatcomesfromthefarm,suchaswheat,oranges,

tomatoes,andcarrots.Thefoodindustryinvolvestheprocessingand



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AGRiCuLTuRE

distributionoffood.Fiberincludesproductslikewoolorcotton.Woolis

thehairofsheepusedtomakeclothing,blankets,andotheritems,and

cottonisaplantproduct.Forestryisthecultivationoftrees.Forestspro-

videwoodproducts,paperproducts,andlandscapingproducts(suchasthedecorativebarkplacedundertreesinlandscapedyards).Flowers,

alsocalledthegreenindustry,includesflowersusedforindoordeco-

rating,plantsforlandscaping,andturf(grasssod)foryards.

About one-fifth of Americans are employed in the agricultural

industry.Theagriculturalindustryiscriticaltooursurvival.Itkeepsus

fed,sheltered,andclothed.Itcanonlycontinueifhumanstakegood

careof thesoil, air,water,andothernatural resources.Effectivecon-

servationofthenaturalresourcesusedinagriculture,aswellasgood

managementtechniques,mustexistsothatfuturegenerationscanenjoy

thebountyfromtheearthaswell.

Ofthetotalsurfaceareaoftheworld,mostofthelandisunsuit -

ableforagriculture.Only1%oftheEarthhassoilavailableforfarming.

About75%of theEarthssurfaceiscoveredbyocean;12%iscovered

withdeserts, swamps,mountains, and polarregions;and12% is too

rocky,toowet,toohot,oralreadybeingusedforbuildings.

where The worlds main food crops are grown

Differentpartsoftheworldaresuitedforproducingthevariousmain

food crops: wheat, corn, potatoes, rice, barley, millet/sorghum, and

starchyroots.Mostofthefoodintheworldisgrowninthetemperate

regionsthosenottoohotortoocold.

DifferentpartsoftheUnitedStatesarebetterforraisingdifferent

cropsorproducts. For example,most fresh fruits and vegetables are

grownintemperateclimates(climatesthatlackextremesintempera-

ture). States that produce lots of fruitsand vegetables areCalifornia,

Florida,andTexas,notonlybecauseoftheirclimatesbutalsobecausetheyhavelongergrowingseasons.

TheGreatPlains(grasslands)growlargeamountsofwheat,barley,

corn,andothergrains.InsomeofthedrierdesertareasoftheWest,

where crops cannot beeasily grown, ranchers graze cattle andother


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The ten major farm production regions of the United States. Each region is

associated with a specific crop or livestock industry. (Source: U.S. Department

of Agriculture)

cane,grass,corn,andrice.Thedesertregionspredominantlyhotand

dryarenotgoodareastogrowcrops.Providingirrigationistoodif-

ficultandexpensive.Mediterraneanclimates,whicharedryandhotin

thesummers,arebestforgrowingbushesandtreesthatproduceolives,

figs,andgrapes.

Mountainclimatesalsoaffectwhatwillgrow.Areasonthesideofthe

mountainthatfacethemainsourceofairflowreceivemorerainthantheareasontheothersideofthemountain.Thisiscalledthe orographic

effect.Asanairmassapproachesamountain, themountainactslikea

barrierandforcestheairmassupward.Astheairrises,itcools,causing

moisture tocondense into rainfall.This iscalled thewindwardsideof



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themountain.Assoonastheairmasspassesoverthemountain,ithas

littlemoistureleft.Thedrieraircausesarainshadoweffect,oraregion

ofreducedrainfall,ontheback(leeward)sideofthemountain.Farmson

thewindwardsidecanbeveryproductive.Altitude(theheightofthelandabovesealevel)isalsoanothercli-

maticfactor:thehigherthealtitude,thecoolerthetemperature.Thatis

whytreesdonotgrowaboveacertainlevelonamountain.Theseareas

aremuchtoocoldtouseforagriculture.Theeffectofclimateandweather

iscriticalonayearlybasis,aswell.Duringyearsofdrought ortoomuch

rainfall,cropscanbedestroyed.Iftemperaturesdropbelowfreezing,fruit

andvegetablecropsmaybedestroyed.Whencropsgetruinedorwhen

thereareyearsoflowproductivity,thisresultsinfoodshortages.Foodis

hardertofindandmoreexpensivetobuy.

The best farmland in the world is in low-lying areaswhere rivers

havedepositedfertilesoilandwheretheclimateismoderate.Soilisone

ofEarthsmostvaluableresources,becauseeverythingthatlivesonland

dependsdirectlyorindirectlyonthe soil.Without soil, farmerscould

notgrowplants,whichmeanstheycouldnotgrowfoodforanimalsor

people.

Soil,althoughitcaneventuallyregenerate,isconsidereda nonrenew-

ableresourcebecauseitformssoslowlythatitcantakehundredsofyears

forjustafewinches(centimeters)toform.Awell-developedsoilthatis

extremelyfertilecouldhavetakenthousandsofyearstodevelop.Because

ofthis,farmersmusttakespecialcarenottoharmthesoil.Ifnutrientsare

removedorthesoiliserodedoroverused,thencropswillnotgrowwell.

Farmersfoundthat,iftheydidnotrotatecrops(plantadifferent

typeeachyear),growingthesamecropallthetimedepletedthenutri-

entsinthesoilandmadethesoilinfertile(notproductive).Thishap-

penedintheSouthinthe1800swiththecottoncrop.Afterafewyears,

cottonwouldnotgrowthereanymore,andmanyfarmersabandonedtheirfarms.Methodsof soil conservationhadtobeputinplaceto

helprestoresoilfertility.

Soilismuchmorethanjustdirt.Itcontainsparticlesofsand,silt,and

clay.Thesearecalledinorganic particles.Theproportionofthesethree


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particleshelpsdetermineswhattypeofsoilitis.Soilthatishighinsand

iseasytoworkwithbecauseithaslotsofopenairspacesbetweenthe

sandgrains,butthismakessandtheleastfertilesoilbecausethewater

drainsthroughitquickly,carriesawayplantnutrients,andleavesthesoildry.Claysoilsaremoredifficulttoworkwithbecausetheytend

tobesticky,buttheyholdmorenutrients.Well-drainedsoilswithlots

oforganicmatterarethemostfertilesoils.

Soil formation isa long, involvedprocess inwhich soil eventually

developsintodistincthorizons(horizontallayers).Whenallthehorizons

arestudied,thisiscalledasoilprofile.Thesurfaceoftheprofileiscalled

the topsoil.Thehorizonsunderneatharecalledthesubsoil,andatthe

bottomoftheprofile isbedrock.The soilcaneitherbeformedinone

place fromtheweatheringof therockmaterial found inthearea,or it

canbemadefromsedimentsthatwerefirstdepositedbywind,water,or

icefromsomewhereelse.Therearemanydifferenttypesofsoilfound

throughouttheworld,dependingontherockmaterialtheyweremade

from(calledparentmaterial).

Soilalsohasotherimportantcomponents.Itmustcontainwater,air

pockets,andmicroorganisms.Tinyorganismsliveondecayingplantsin

thesoil,turningtheplantsintohumus.Humusmakessoilsmoreproduc-

tivebecauseitabsorbsheat,holdsmoremoisture,andprovidesfoodforgrowingplants.

Soilformationisalsocontrolledbytemperature,climate,andvegeta-

tion.Soilisnecessary fortheproductionofalmostallofourfoodand

fiber.Evencropsgrowninawaterenvironmentlikericerelyonthe

nutrientsfoundinsoil.

Soilprovides13ofthe16nutrientsneededforplantgrowth:nitrogen,

phosphorus,calcium,sulfur,copper,boron,zinc,manganese,molybde-

num,chlorine,iron,magnesium,andpotassium.Thesenutrientscome

fromtheweatheredmineralsanddecayedplantmatterfoundinthesoil.Inaddition, carbon, hydrogen, andoxygen are stored intheairspaces

betweensoilparticles.

Soil helps filter and purify water. When water travels over or

throughsoilbeforeenteringriversorlakes,thesoilhelpspreventflood-



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ingbyallowingexcesswatertosoakinforusebyplantsortopercolate

(flowthrough)tootherundergroundwaterbodies,calledaquifers.Soil

helps purify contaminated water by removing the impurities and by

killing potential disease-causing organisms. Soil is important becauseit recycles dead plants and animals into the nutrients needed by all

livingthings.

Erosionbywindorwateristhemostseriousthreattothehealth

ofthesoil.Thisiswhysoilconservationpracticesaresoimportant.

how a farm works

Howafarmworksdependsonmanyconditions.Itdependsonthetypeof

climatetheregionhas(forexample,ifacropneedsawarm,moistclimate,

itwillnotgrowinadrydesert);thelengthofthegrowingday(meaning

thatareasthathavemorehoursofdaylightwillbeuseddifferentlythan

thosewithashorternumberofdaylighthours);thetemperaturerange;

theamountofprecipitationinthearea;thetypeofsoilintheregion(for

example,cropsdonotgrowwellindry,sandysoil);thesizeofthefarm

(ifthefarmissmall,itcannotgrowmanyacresoforchards);thenumber

ofemployeesthefarmisabletohire(somecropsaremorelabor-intensive

andrequiremorepeople);andthetypeofequipmentnecessarytorun

thefarm(someequipmentmaybetooexpensiveforasinglefarmertobuy).Thesefactorswillvarybasedonthetypeofproductproducedon

theland.

Farmersindevelopedcountries,liketheUnitedStates,Canada,coun-

triesinWesternEurope,andAustralia,havedevelopedamodernwayof

farming.Unlikefarmersinthepastorfarmersindevelopingcountries

today,mostofthejobsoncedonebyhandarenowdonebymachines.

Thetractoristhemostimportantmachine.Thefarmerusesittopushor

pulldifferentkindsofequipment,suchasaplow,aharrowforbreaking

upchunksofearth,oraseeddrillforplanting.Whenhayisgrown,abiglawnmovercalledaswatherisused.Hayis

astaplefoodforfarmanimals.Hayisdriedalfalfaordriedgrass.Alfalfa

isusuallydarkergreenincolor,whilegrassisalightergreen.Whenthe

swathercutshay,ithasarubberrollerinsidethatcrimpsthecutstems


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Rectangular bales of hay produced from a baler. (Courtesy of the U.S.

Department of Agriculture; photo by Ken Hammond)


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Sheep are another common farm animal. There are about 800

breedsofdomesticatedsheepintheworld.Somesheepareusedto

producemilkandcheese. Farmers alsoharvest theirwool tomake

clothesandblankets.Somefarmersraisellamastoprotectthesheep.A llama is amember of the camelid family, but it does not have

humpslikeitscousin,thecamel.Goatsareimportantfarmanimals

all overtheworldbecause theycan live inmountainous, dryareas

whereotherfarmanimals(likecows)cannotsurvive.Goatsareoften

usedtoproducemilk.

Thedonkeyisanothercommonfarmanimalthathasbeenused

forthousandsofyears.Donkeyscanbeusedforriding,pullingcarts,

orcarryingloads.Mulesarealsofoundonfarms.Amuleisacross

betweenafemalehorseandamaledonkey.Mulesareverystrongand

sure-footed.Otherfarmanimalsincludeturkeys,ducks,geese,andelk.

Dogsandhorsesareusedonfarmstohelpherdanimals.

AninterestinganimalfoundonsomeAmericanfarmsisthebeef-

aloacrossbetweentheAmericanbisonandcattle.Thebeefaloisa

hearty,stronganimal.Itcantoleratetheheatandthecold.Thebeefalo

doesnotrequirespecificgrassesforfeed,butinsteadisabletoeatwhat-

evergrassesareavailable.Becausetheseanimalsareeasytohandleand

producerichmilk,theymakeagoodfarmresource.Farms produce many types of produce, such as cherries, pears,

peaches,apples,oranges,andapricots.Wheretheyaregrowndepends

ontheclimate,temperature,andgrowingseason.Iffruittreesfreezein

thespringoncetheblossomsareout,thefruitcropforthatyearcan

bedestroyed.

ManytypesofgrainaregrownonAmericanfarms,suchasbarley,

sorghum,soybeans,rice,andwheat.Thereareavarietyofvegetables

grown on farms. Some of themost common are potatoes, carrots,

beets,turnips,onions,garlic,lettuce,asparagus,greenbeans,cabbage,squash,pumpkins,corn,greenpeas,peppers,andsweetpotatoes.In

manyplacesacrosstheUnitedStates,farmerscollecttheproducethey

have grownand sell it atfarmers markets,which are very popular

becausetheproduceisalwaysfresh.



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Althoughmodernagricultureismuchmoreefficientandmorefood

canbeproducedtodaythaneverbefore,sometimestherearedrawbacks.

Manyfarmersusechemicalstoimprovetheirproduce.Theyusefertilizerstohelpcropsgrowandherbicidesandpesticides tokillweedsandinsects

thatcandamagecrops.

Some farmershave stoppedusing chemicals and have switched toorganic farmingandapracticecalled crop rotation(growingdifferent

cropseachseason)tokeeppestsdowninsteadofusingpesticides.They

useanimalmanureinsteadofchemicalfertilizersandherbalremedies

insteadofantibiotics.

A combine harvester cultivates a wheat crop. (Courtesy of the U.S. Department

of Agriculture)


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Another problemwithmodern farming isthatsometimes farmers

growsomuchgrainthattheycannotsellitataprofit.Sometimesgov-

ernmentsbuyitand store it.Governmentstrytokeepthe supplyand

demandbalancedsothatfarmersdonotgrowtoomuchandlosemoneyordonotgrowenoughandmakefoodpricesriseoutofcontrol.Itisa

challengetobalancefoodsuppliestoaccommodatesurpluses(areaswith

toomuchfood)andshortages(areaswithtoolittlefood).Sometimesin

developedcountries,governmentspayfarmersasubsidynottoproduce

toomuch.Othergovernmentshavetriedfiningfarmersforproducingtoo

muchofacommodity.

Inless-developed,poorercountries,thereisadifferentproblem:not

enoughfoodtofeedthepopulation.Famine,starvation,andmalnutri-

tionarecommonproblemsinthesecountries.Sometimes,othercoun-

trieswillsendemergencyfoodsuppliestothesenations,butthisisnot

along-termsolution.Farmersinthesecountriesneedtoproducetheir

ownfoodandadoptlandconservationpracticesthatallowthemtofarm

moreproductively.Sometimesthereasonsforshortagesarefinancial,but

inotherinstances,farmersjustlackthepropereducation.Theseissuesare

coveredinmoredetailinlaterchapters.

The ThreaT of invasive planTs and weeds

Native plantshaveevolvedovermillionsofyearstofilluniqueecological

niches.Invasiveweedsarenonnative(didnotoriginateintheareathey

aregrowingin)andecologicallydamagingplants.

Invasiveweedsareplantsthatdevelopedinotherregions.Growingin

theirownregions,theyarenotconsideredinvasiveweedsthatharmthe

environmentbecausetheydevelopedwithinthelocalecosystem.Theyare

naturallycontrolledbycompetitionwithotherplantsandbyinsects,dis-

eases,andotherpredators.Whentheirpopulationincreasesintheregion

theyoriginatedin,insectsandotherpredatorskeepthemundercontrol.Thetermweedisusedtodescribeanyplantthatisunwantedand

growsorspreadsaggressively.Aninvasiveplantisaplantthatisgrowing

whereitshouldnotbe.Apineappleinapumpkinpatchwouldbean

exampleofaninvasiveplantbecauseitdoesnotbelongthere,justasan



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orchidwouldbeinastrawberrypatch.Someinvasiveplantsbecomea

problembecausetheygrowaggressivelyandcrowdoutnativeplants.

Oneofthegreatestobstaclesscientistsandlandmanagersfacetoday

inpromotingecosystem healthistherapidexpansionofinvasiveplants.Someinvasiveplantsandnoxiousweeds(whichareharmfultohumanor

animalhealth)canproducesignificantchangestovegetation,composi-

tion,structure,andecosystemfunction.Theseaggressivelygrowingplants

destroy farmland and wildlife habitat and can reduce plant diversity

(chokeoutothertypesofplants).

Weeds know no boundaries. They are invading government-

managedpublicland,farms,forests,parks,andprivatelands.Millionsof

Theoodandfberindustryaccountsor20%oAmericas

productionandemploys20%oourpopulation.

AgricultureistheUnitedStatesbiggestemployer.More

than21millionpeoplehaveajobthatisrelatedto

agricultureandtheoodindustry.

Onearmercaneed129people. Americansspendroughly$2,328eachyearonoodor

eachperson.

Intheyear1900,ittook35to40laborhourstoproduce100

bushelsocorn.Today,only2.5hoursand1acreoland

areneededtoproducethesameamount.

Thereare2.7millionarmsintheUnitedStates.Women

operated145,156othosearms.

In1994,armersplaced36.4millionacresotheirlandin

reservetoprotecttheenvironmentandprovidehabitator

wildlie.Thismeansthatarmsandranchesprovide

habitator75%othenationswildlie.

Adapted from the Utah Agricultural Applied Technology Program,

http://www.usoe.k12.ut.us/ate/ag/

Facts About American Agriculture


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acresofoncehealthy,productiverangelands,forestedlands,andriparian

(river)areashavebeenoverrunbynoxiousorinvasiveweeds.Weedscan

dominateandcausepermanentdamagetonaturalplantcommunities.

Scientistsandlandmanagersrealizetheseriousnessofthisproblemandunderstandthat,ifweedsarenotcontrolled,theycandamagethehealth

oftheland.

Thisproblemisespeciallypronouncedinthewesternregionsofthe

UnitedStates.Becausesomuchranchingandgrazingoflivestockoccurs

onprivateranchesandpublic landsintheWest,weedsposeanincreased

threattothehealthofthelandthere.Ifweedsareallowedtotakeover

anareaandcompetewithnativeplantsforsoilnutrientsandspace,the

nativeplantswilldie.Becauselivestockgrazethenativeplantsanddepend

onthesefortheirfoodsupply,weedsneedtobecontrolled.

Thesameconceptappliestofarming.Ifweedsinvadefertilelandand

competewiththecropsfornutrientsinthesoilandgrowingspace,they

willkeepfarmsfrombeingproductive.Weedscanspreadinmanyways.

Theycanbespreadbyhumanactivity,birds,animals,wind,andwater.

EarlyEuropeansettlersinNorthAmericaunwittinglybroughtalotof

weedseedswiththem.Theseedscouldhavebeenhiddeninthehaythey

broughtoverfortheiranimals,inthedirttheyusedasballastfortheir

ships,inthefleeceandhairoflivestock,intheirclothesandbedding,oraccidentallymixedinwithpartoftheseedsbroughtovertoplant.

Somehumanactivities,suchasclearingthelandtobuildonorfarm,

createdopenplacesforweeds togrow.Settlers also purposelybrought

plants fromtheir countriesoforigin to reseedareas intheirnew land,

makedyeforclothing,oruseasornamentalplants(asdecorations).Some

oftheseintroducedplantsmayhavebecomeweeds.

Whenplantsareintroducedtoanewenvironment,theymaynothave

anynaturalenemiestokeepthemundercontrol.Becauseofthat,theyare

notdestroyedbydisease,insects,orotherpredators.Withoutanynaturalenemiessomeoftheseplantsbecomeinvasive(growwheretheyarenot

wanted)andlowerthediversityandquantityofnativeplants.

WeedsarespreadingrapidlyintheUnitedStates.Accordingtothe

BureauofLandManagement, in thewesternUnitedStates, weeds are



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Purple Loosestrife

Eachfoweringstalkcanproduce100,000to300,000seedseachyear.

Asmallclustercanspreadandcoveramarshinonegrowing

season.

Birdsandmammalsdonoteatit,soiittakesoveranarea,

thewildliehabitatislost.

Knapweed

Oneplantproducesabout1,000seedsthatcanremainertile

or8to20years.

Theseedsarecontainedinare-resistantstem.Somepeopleareallergictoit,anditcanirritatetheirskin.

Leafy Spurge

Seedscangerminaterom6inches(15centimeters)below

thesuraceotheground.

Rootscanbeound15eet(4.5meters)intheground.

Themilkyjuiceintheleavesandstemsispoisonoustomost

livestock.

Theseedcapsulesexplodewhentheyaredryandcanshoot

theseedsasaras15eet(4.5meters).Theseedscanstillgrowatersittingor8yearsormore.

Gorse

Itgrowsrapidlyandlivesormorethan15years.

Thebrancheshaveahighoilcontent,whichcausesaserious

rehazard.

Itproducesabout8,000hard-coatedseedseachyear,which

areejectedbyburstingpodsandcanlaydormant(notactive)

inthesoilor40yearsormore.

Burningandcuttinggorsedoesnotgetridoitbutrather

encouragesittogrowmore.

Itorcesthenativevegetationoutandisverydicultto

controlonceittakesoveranarea.

Source: British Columbia Forest Service

Facts About Weeds


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spreadingroughly4,000acres(morethan6squaremilesor15.5square

kilometers)eachdayonpubliclands.Theyarealsospreadingonpri-

vatelands,includingagriculturalfarmingareas.Althoughsomeweeds

havebeautifulflowers,theycancauseseriousecologicaldamage.Weedstakeoverimportanthabitatareasforwildlife,destroyingshelterand

nutrientsandreducingthenumberandtypeofnativeplantsthatcan

growinthearea.

Whenweedsdonotholdorprotectthesoilthewaynativeplantsdo,

erosionincreases,causingsedimentstobuildupinstreams.Thisinturn

canhurtfishpopulationsandwaterquality.

Someweeds,callednoxiousweeds,areahealthhazardforhumans

oranimalsbecause theyare poisonous. For example, leafy spurge can

causeblindness, skin irritation,andblisters.Hemlockispoisonousand

can cause death.Other weeds arehallucinogenic and can causedeath,

andmanycauseallergicreactionsinpeople.Weedsalsoposeaproblem

incontrollingwildfires.Generally,theyarelessresistanttowildfirethan

nativeplants.Weedsalsoreducethevalueoftheland.Theyhaveahuge

impactonranchingandagriculturalactivitiesbecausetheycanreduce

theproductionofcrops.Weedsareaproblemallacrossthecountry,and

controllingthemcanbeverydifficult.Oncefarmers,ranchers,andothers

realizethereisaweedinfestation

,itisusuallybigenoughthatitishardandexpensive toeradicate.Biologicalcontrol(usingorganismssuchas

introducedinsectsordiseasestoreducepopulations)iseffectiveinslow-

ingthespreadofweeds,butitusuallycannotgetridofalltheweeds.

Farmersandrancherscanpulltheweedsbyhandorusemachinestodig

themup,butthisisusuallyonlydonewithsmallinfestations.Whenfarm-

erspullweeds,theymustbecarefulthattheydonotaccidentallyspread

anynewseeds.Herbicidesarealsogoodforcontrollingweedsandstop-

pingtheirspreadwhentheyarefoundearly.Mostlandmanagersusean

integratedapproach,usingacombinationofthesemethods.Itisimportantinagriculture,ranching,andotheractivitiestolearn

aboutweedsandgetridofthem.Anaturalfunctioningecosystemcan

easilybethrownoutofbalancebyaninvadingspecies.Controllingweeds

usually involvesthehelpofseveralpeople.Itinvolvesawareness,detec-



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tion, prevention, planning, treatment, coordination,andmonitoringto

solvetheproblem.

Examplesofinvasiveweedsincludepurpleloosestrife(intheeastern

andwesternUnitedStates);spottedknapweed(intheeasternandwestern

Inordertounderstandtheseverityoftheinvasiveweedproblemand

therapidexpansionofweedcommunities,wewilllookattherateof

reproductionofoneknapweedduringthecourseof10years.Wewill

assumethat100knapweedseedsaredroppedinanareaatonetime.A

knapweedplantproduces1,000seedsperplant.Oftheknapweedseeds,

4%willgerminate(sprout)eachyear,leaving96%forthefollowingyears

seedbank.Ofthis,25%oftheseedlingsthatsproutwillsurvivetobecome

matureplants.Theknapweedseedsremainviable(abletogerminate)

for8years.Ittakes1yearforknapweedtogerminateandproduceseed.

Knapweedplantslivefor5years.Thefollowingtableshowshowmany

plantsandseedswillbeproducedovertheareainthenext10years:

Year Plants Seeds

0 0 1001 1 1,096

2 12 13,052

3 143 155,530

4 1,698 1,847,309

5 20,071 21,944,417

6 239,614 260,680,640

7 2,846,408 3,096,661,414

8 33,812,879 36,785,673,858

9 401.667,920 436,982,165,807

10 4,771,469,402 5,190,972,273,123

Morethan5billionseedsin10yearsthatmeansalotofweeds!

Data supplied courtesy of the U.S. Bureau of Land Management

Weed Multiplication


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UnitedStates),whichcan produce 1,000seedsper plantandwhose

seedscanlaydormantforeightyears;leafyspurge(inthenorthern

UnitedStates),whichhasapowerfulrootsystemthatcanpenetrate25

feet(7.6meters)deep;yellowstarthistle(mainlyinthewesternUnitedStates); dalmatian toadflax; garlic mustard, which threatens native

springwildflowers;Orientalbittersweet(intheeasternUnitedStates),whichisatwiningvinethatcansmothertreesandsaplings;waterhya-

cinth,whichclogsaquaticecosystems;andmelaleuca,atreethathas

invadedtheFloridaEverglades.

Thediversityofournativeplantcommunitiesisdecreasingasecosys-

temsarebeingdamagedbyweeds.Asnativevegetationisreduced,sois

theamountofforage availableforwildlifeandlivestock.

land sTewardshipmainTaining The healTh of

privaTely owned land

Landstewardshipistheconceptthatpeoplemusttakecareoftheland

nowaswellasinthe future.Beinga stewardofthe landmeans taking

responsibilityforthelandandmanagingitforitslong-termwelfare.This

isnosmalltask.Sometimesitishardenoughtomakedecisionsabout

issuesaffectingthepresent.Itisevenhardertoplanfor5,10,15,or20

yearsintothefutureandtotakeactionforthelandswelfarenow.Justasastudentwholookstowardhisorherfutureandwantstoend

upwithagoodcareertakespreparatorystepstoachievethatgoal,sotoo

muststewardsofthelandplanahead.Astudentpreparesforhisorher

futurecareerbytakingclassesinmiddleschoolandhighschoolthatbuild

afoundationandthencontinuingontocollegeandrefiningthetraining.

Bythetimealltheclasseshavebeencompletedanditistimetograduate,

thestudentisfinallyreadyforthecareerwhoseplansbegantotakeshape

yearsbefore.Similarly,landstewardshipinvolvesplanningaheadandtak-

ingcareofthelandsnaturalresourcessothattheywillbeavailableforfuturegenerationstouseandenjoy.Forexample,ifhumansdonottake

careofthequalityofourwatertoday,then10yearsfromnowitmightbe

toopollutedtouse.Iffarmersoverfarmthelandandmakethesoilworth-

less,futuregenerationswillnotbeabletofarmit.



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Farmers todaymust meet the needs of the presentwithout com-

promising the ability of future generations to meet their own needs.

Stewardshipofthelandanditsnaturalresourcesinvolvesmanagingitso

thatthesameresourcesarethereforthelongterm.Leavingthecondi-tionoftheresourcesinevenbettershapethanwhenwegotthemisthe

ultimategoal.

Like anything, this involves a plan. People must be educated and

recordsmustbekeptonmanagementtechniquessothatfuturegenera-

tionscanuseorimproveonthosetechniques.Witheffectivesteward-

shipoftheland,humansgetmanybenefits:fertilesoils,anabundance

ofcrops,safedrinkingwater,clearstreams,lakesfulloffish,skiesfullof

birds,andbeautifullandscapes.

LandstewardshipbeganintheUnitedStatesin1935,afterthedev-

astationoftheDust Bowl.Thenationmadeahistoriccommitmentto

the stewardship of private land by passing the Soil ConservationAct.

Generationstodayarebenefitingfromthepositivestepsoflandsteward-

shipstarted70yearsago.JustasintheDustBowldays,everyoneisinthis

together,andeachofusmusttakepartinlandstewardshipifitistosuc-

ceed.Theultimategoalis,throughourpersonalactions,toleavetheland

inbetterconditionthanwefoundit.


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The hisTOry Of

AmeriCAn fArming

CHAPTER

2

A

merican farmers today are conservationists.Theyneedtobe,

because the land is their livelihood. Itdidnotalwaysused to

bethatway,however.Manymistakesandlearningexperiencesoverthepast200yearshelpedtoshapecurrentfarmingintowhatithas

become.Farmersarestilllearningstillworkingathavingthebestrela-

tionshiptheycanwiththeland.Thischaptertakesalookatthehistoryof

Americanfarmingandthetragiceventsthatoccurredbeforetheconcept

oflandstewardshipcameintobeing.

The developmenT and evoluTion of farming

in america

Farmersmadeupabout90%oftheAmericanworkforceinthelateeighteenth andearlynineteenth centuries.A lot of earlyAmerican

farmingtechniquescamefrompracticesusedatthattimeinEngland

(because many new immigrants to the United States came from

England).


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AGRiCuLTuRE

Thefarmers yearbeginsinthespringassoonasthegroundcanbe

plowedusuallyaroundMarch.Fieldsareplowed,seedsareplanted,

and crops are cultivatedand tendeduntil they are ready to be har-

vested.Dependingonthecrop,harvestsusuallyhappeninlatesummer

orearlyfall.Somecrops,likealfalfaandhay,areabletobeharvested

earliersometimesearlyenoughsothatanothercropcanbeplanted

andharvestedinthesamegrowingseason.

Manualfarmingrequiredalotofpeopletoplow,plant,andhar-vestthecrops.Thefarmsprosperitydependedgreatlyontheskillof

the plowing. Plowing isvery hardwork, andnoother farm activity

requiredsomuchexperienceandjudgment.Thefarmershadtoknow

when to plow,howdeep to plow,andwhere to set the first furrow

Workers pick string beans in a field in Muskogee, Oklahoma, in June 1939.

(Courtesy of the U.S. Department of Agriculture; photo by Russell Lee)


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THE HisToRy oF AMERiCAN FARMiNG

(plowedrow).Thefarmergainedthisknowledgebyunderstandingthe

soil,theterrain,andthecharacteristicsofthefuturecrop.

Physically,plowingwasa tremendouschallenge.Thefarmerhadto

keep400pounds(181kilograms)ofwoodandsteelsteadyataconsistentdepthwhilewalkinginuneven,softsoil.Itwasoftenabalancingactto

keeptheplowlevelandthehorsesthatpulleditinastraightline.

Onceafieldwasplowed,itneededtobeplanted.Theearlyfarmer

sowed(planted)seedsbyhandashewalkedalongthelengthofthefur-

rows,keepinghispacesteadyandtryingtoscatterthesameamountof

seedeverywhere.Oftentimes,theseedsweremeasuredintosacksand

setattheendsofthefurrowssothepersonsowingknewhowmany

seedstoplantalongagivenrow.Thefarmerwouldcounthisstepsand

estimatehowmuchseedneededtobescatteredwitheachstep.

By 1850, the populationof theUnitedStates had grownsignifi-

cantly,yetonly64%oftheworkforcewasemployedinagriculture.The

farmersintheoriginal13coloniesbegantopushtheirwaywestward

totheGreatPlains,lookingformorelandtofarm.

TheAmericanWestprovidedlargeareasoflandforraisingcrops

and livestock, so the expansion westward rapidly continued. Once

farmersbegantofarmtheWest,theyrealizedthatthearidclimate(hot

anddry)madetheuseofnew,large-scalefarmingmethodsnecessary.FarmersintheWestwereabletogrowfruit,vegetables,andwheatas

wellasraisecattle.

By1870,thedemandsofwesternfarmingtriggeredthefastgrowth

ofthefarmequipmentindustry.Farmsweregettingtoobigtobeable

toperformallthelabormanually.Oncefarmershadthisequipment,

theybeganfarmingevenbiggerpiecesofland.Between1870and1900,

more landwas turned into farmsthan in the 250 years before that.

Duringthelate1800s,therewasalsoalargeincreaseinranchingand

thecattleindustry.Ranchersgrazedtheircattleonwesternprairiesandhiredcowboystohelpmanageanddrivetheirherds.

Intheearly1900s,becauseofthedryclimate,westernfarmershad

toworkalotoflandinordertomakeanymoney.In1909,theU.S.

CongresspassedtheEnlargedHomesteadAct,whichallowedsettlers


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AGRiCuLTuRE0

inthearidwesternstatestoownlargerpiecesofland.Thattimeuntil

the1920sbecameknownastheGoldenAgeinagriculture;accordingto

theU.S.LibraryofCongress,farmersmadetwiceasmuchmoney,and

thevalueoftheirfarmsincreasedby300%.Machines that could automatically plant seeds (called seed drills)

weredeveloped,makinglifealittleeasierforfarmers.Later,evenmore

sophisticated planting machines appeared. Thesemachines served as

mowers,reapers,harvesters,andthrashers.In1912,theautoplowwas

invented.Itwasatractorwiththeplowbladesalreadymountedtothe

bottomofthetractor.Thefirsttractorswithenclosedcabsappearedin

thelate1930s,furthermodernizingfarming.Today,plowsarepulledby

largetractorsandcancoverlargetractsoflandinasingleday.

Today,mostaspectsof farmingaremechanized,buttherearestill

farmersinAmericawhomaintainthetraditionalfarmpracticesfrom

centuries ago.These are theMennonite farmers of Indiana, Illinois,

Ohio,andPennsylvania.Theyhavepreserved theAmerican farming

tradition,andthroughhardworkanddedication,theyworkwiththe

landforitsbounty.

The u.s. deparTmenT of agriculTure

In 1791, President George Washington received a letter from anEnglishmannamedArthurYoung.Mr.Youngwaslookingforinfor-

mationonlandvalues,crops,yields,livestockprices,andtaxes.George

Washingtondidnothavetheanswers,sohedecidedtoconductamail

survey toaskfarmersfortheinformationandthencompilea report

ontheresults.

Afterwaitingforseveralmonthstogetthefarmersresponsesback

inthemail,Washingtonwasabletogetenoughinformationtogetherto

replytoArthurYoungandanswerhisquestions.Thisreport,prepared

by George Washington, became the United States first agriculturalsurvey.Itdetailedagriculturalinformationforanarea250miles(402

kilometers)fromnorthtosouthand100miles(161kilometers)from

easttowestanareathatliesinPennsylvania,WestVirginia,Virginia,

Maryland,andWashington,D.C.


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GeorgeWashington was very concerned about conservation of

farmland.Hestressedthatfarmersshouldcontinuetoimprovetheir

landinsteadofexhausting(overusing)it.Hisconcernswereverysimi-

lartotheconcernsfarmershavetoday.Heworriedthatpriceswerenotkeepingupwithwhatitwascostingtogrowthecrops,andfarmers

werelosingmoney.Heworriedthatsomefarmerswerenottakingcare

oftheirland.Healsoworriedaboutthecostoftransportingagricul-

turalgoods tomarkets and improving transportation routes so that

farmersdidnotlosetheirprofits.

GeorgeWashington also criticized many farmers for taking the

abundanceoflandtheyhadtoworkwithforgrantedandnotcaring

foritproperly.Unfortunately,Americanfarmershadtolearnthehard

waythatthisresourcewasnotlimitless,althoughbackthenitprobably

seemedtobe.

In1796,GeorgeWashington suggested that aNational Boardof

Agriculturebeformedinordertoservefarmersbetter,butCongress

rejected the idea.The next major step in American agriculture did

not happen until 1839. Commissioner of Patents Henry Ellsworth,

convincedCongresstodesignate$1,000fromthePatentOfficeFund

for collecting and distributing seeds and collecting data about the

countrysfarms.Ayearlater,in1840,agreatdealofagriculturalinformationwascol-

lectedthroughthefirstofficialCensus ofAgriculture,whichprovidedagricultural information about the entire country. When Ellsworth

receivedthecensusinformation,hecombineditwithotherinformation

hehadcollectedandwasabletoestimatetheagriculturalproductionof

eachstateandterritory.Hisestimatesbeganthepatternthatthegovern-

mentstillfollowstodayforannualagriculturalreports.

AbrahamLincolnestablishedtheU.S.DepartmentofAgriculture

(USDA)in1862.HecalleditthePeoplesDepartment.TheUSDAsfirstofficialcropreportwaspublishedin1863.Atthattime,theUSDAcre-

atedaDivisionofStatistics.DuringtheCivilWar,theUSDAcollected

andpublishedcropandlivestockstatisticstohelpfarmersdetermine

what theirgoodswereworth.Backthen, themerchantswhobought



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AGRiCuLTuRE

theproductsfromfarmersknewmoreaboutcriticalmarketinforma-

tionthanthefarmersthemselves.Becauseofthat,farmersweretaken

advantage of and didnotmake as muchmoney as they needed to.

Statisticsstillkeepfarmersfrombeingcheatedtoday.TheUSDAsCropReportingBoardwasaveryimportantdevelop-

ment.Itestablishedanationwidestatisticsserviceforagriculture,which

isnowcalledtheNationalAgriculturalStatisticsService(NASS).

Today,Americanagricultureisalwaysbeingcountedandmeasured,

andpricesareanalyzedandreportedsothatpeoplehavemeaningful

information.NASS conductsweekly,monthly,quarterly (every three

months),andannual(yearly)surveys.Italsoconductsafive-yearcen-

susofagriculture(from1840to1920,itwasonlytakenevery10years).

The surveys collect information about all kindsof subjects, such as

productionandcurrentsuppliesoffoodandlivestockaswellasfarm-

ersincomes.Landuseandownership,theamountofirrigatedland,

fertilizersandchemicalsused,andtypesofmachineryandequipment

usedarealsodeterminedfromthesurveys.Thesurveysprovidecurrent

informationaboutproduction,economics,andenvironmentaltopics.

Thefive-yearcensusofagricultureisthemostcomprehensive,detailed

information-gathering program for agriculture anywhere. NASS is

oftenreferredtoastheFactFindersofAgriculture.Besideshelpingthefarmergetafairpriceforproductsheorsheproduces,theCensusof

AgriculturedatahelpstheUnitedStatesplanforthefuturebyhavinga

safeandsecurefoodsupply.

The realiTy of overuse and erosion

Erosionistheprocessofwearingawaythesurfaceof the land.Ithas

alwaystakenplace,andalwayswill,becauseitisanaturalprocess.The

surfaceof theEarth isconstantlychanging;mountains are liftedup,

andstreamsbegintoerodethemaway;valleysarecutdeeperbyrivers,andcoastlineschangewiththeactionoftheoceans.

Whilecertainaspectsoferosionareactuallyhelpfulitisthrough

erosionprocessesthatsoilsareformedsometypesoferosioncanbe

verydamagingtotheland.Soilerosioncausedbyhumanactivityis


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oneofthemostdestructiveerosionalforces.Becauseartificiallycreated

erosioncanhappenmuchmorequicklythannaturalgeologicerosion,

itissometimesreferredtoasaccelerated erosion.

Human activityon the landscapecan significantly contribute tosoilerosion.Inanaturalstate,vegetationservesasnaturalprotection

againsterosionbecausethenetworkofrootshelpsholdthesoilinplace

againstvariouserosiveforces,suchaswindandwater.Scientistsesti-

matethat,intheUnitedStates,30%oferosionisduetonaturalforces

and70%isduetohumanimpact.Oftentimes,whenpeopleusethe

landforfarmingandovergrazing,theprotectivecoveringofnatural

vegetationisdestroyed,andtheerosionprocessspeedsup.Infact,stud-

ieshaveshownthatartificiallycreatederosionplayedabigpartinthe

downfallofmanyearlycivilizations.Poorlandmanagementpractices

degradedthesoiluntilitwasnolongerproductiveenoughtosupport

thepopulationlivinginthearea.Earlycivilizationsthatrecognizedthe

disastrouseffectsoferosionuseddevicessuchas terracingthelandto

keep fromplowing, planting, andirrigatingonhillsideslopeswhere

watercouldwashthefertilesoilaway.

There aremany causes of erosion. It can occur by wind, water,

drought,overfarming,lackofground cover,andovergrazing.Erosion

bywindisworseinaridandsemiaridareas.Itremovessoilandnaturalvegetationandcausesdrynessanddeteriorationofthesoilstructure.

Watererosionisgreatestwhenheavyrainstormsfallonlandthat

isunprotectedbyvegetation.Somesoilsaremoreeasilyerodedthan

others.Rill erosionoccurswhenmanytinywaterchannelsareformed.

Interrill erosionhappenswhena layerof soil is removed.Gully ero-

sionhappenswhenthinwatercolumnsquicklyremovethesoilfrom

anarea.Saltation erosionistheremovalofsoilandmineralsbywind,

water,orgravity.

Overuse and erosion of the land can rob the soil of valuablenutrients,making it unproductive. Every year in the United States,

thousandsofacresofarable landarelost.Between1990and2000,the

UnitedStateslostalmost44millionacresofarableland.Someofthis

landwaslostbecausehomes,parkinglots,andotherstructureswere



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AGRiCuLTuRE

Unchecked water erosion in a field. (Courtesy of the U.S. Department of

Agriculture; photo by Ron Nichols)


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builtonit;someofthelandwaspollutedbyindustrialwaterandother

pollutants;someofthelandblewawayorwashedaway;andsomeofthe

landwaslostbecauseithadbeenusedtoproducefoodyearafteryearfor

toomanyyears.Oncethelandhasbeenoverusedoreroded,itisoftennonrenewablebecausesoiltakestoolongtore-form.Thisisoneofthe

mostimportantissuesinlandstewardship.

The dusT Bowl of The 0s

Ittookmanyyearsandtheextensiveerosionandlossofvaluableagri-

cultural soil beforeAmerican farmers learned the lesson thatGeorge

Washingtonwastryingtoteachbackin1788.Theworstlossofagricul-

turalsoilinAmericanhistoryoccurredduringtheearly1900s.

DuringWorldWarI(1914-1918),thereweresignificantwheatshort-

ages,whichcausedthepriceofwheattorisedramatically.Atthattime,

wheatwasveryprofitablefarmerscouldmakealotofmoneyselling

it.TheU.S.governmentencouragedfarmerstoproducemorewheat,so

farmersonthefragilesouthernGreatPlainsplowedupthenaturalgrass

cover,whichhadprotectedthesoilforcenturies,toplantwinterwheat.

TheGreat Plains extend eastward from the RockyMountains across

the western parts ofNorthDakota, SouthDakota,Nebraska,Kansas,

Oklahoma,andTexas.Soon,thewheatcropsexhaustedthetopsoil.Inaddition,overgrazing

by cattle and sheepherdsstripped thewesternplains of theirprotec-

tivegrasscover.Thentheareawasdevastatedbyaseveredroughtfrom

1934to1937.Becausethelandhadbeenplowedup,andthedelicate,

stabilizingrootsystemsformedbythegrassremoved,thelargeplowed

areashadnothingtokeepthemanchoredinplace.Alotofthesoildried

out, turned to dust, and blew away. The area was coveredwith hor-

ribleduststormsandsandstormsthatburiedroads,houses,towns,and

fields.CloudsofdustwereblownasfarawayasChicago,NewYork,andWashington,D.C.Itturnedtheskiesdark.Eventually,thesoilblewout

overtheAtlanticOcean,whereitwaslostforever.

ThisareawascalledtheDustBowl.Itcoveredanarea500miles(805

kilometers)by300miles(483kilometers)insizealmost100million



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AGRiCuLTuRE

acresofland.Thedroughtandtopsoillosslasteduntil1938.Manypeo-

plewholivedintheDustBowlstatesabandonedtheirfarmsandmovedaway.TheDustBowlexoduswasthelargestmigrationinAmericanhis-

tory.By1940,2.5millionpeoplehadmovedoutoftheGreatPlains.

Inresponsetothisdisaster,thefederalgovernmentcreatedtheSoil

Erosion Service (SES) and the Civilian Conservation Corps (CCC)

torecoverthe land.Manyconservationpracticeswerebegun, suchas

replantingthegrass,plantingtreewindbreaks(calledshelter belts),crop

rotation,contour plowing,andstrip plowing.TheSESandCCCalso

showedfarmersnewscientificagriculturalmethodstohelpthempro-

tectthefragileecosystemoftheSouthernPlains.ThehistorianRobertWorsterwrotethefollowingaboutthisperiod:

Theultimatemeaningoftheduststormsofthe1930swas

thatAmericaasawhole,notjustthePlains,wasbadlyoutof

The Dust Bowl of the 1930s. A dust storm approaches Stratford, Texas, in April

1935. (Courtesy of the USDA Wind Erosion Research Unit; photo by George

E. Marsh)


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Peopleinvolvedinagriculturethroughoutthecountryarealways

lookingornewandinnovativewaystoconservenaturalresourcesand

improvearmingtechniques.Forexample,armersinthenortheastern

UnitedStatesbeganlookingorawaytoextendthegrowingseason

sotheycouldproduceoodlonger.Somearenowusinghightunnels.

Thesearesimpleplastic-coveredstructuresthatkeepcropswarmand

sheltered.Hightunnelsresemblegreenhouses,buttheycostmustless

tobuildandoperate.Tomakeahightunnel,aarmerstretchesalayer

oclearplasticsheetingoverametalpiperameabout20by100eet

(6by30meters)insize.Thestructuresareeasytouse,andtheplastic

sidescanevenberolleduptoallowreshairtocirculatearoundthecrops.Farmershavebeenabletoaddweekssometimesmonthsto

theirgrowingseasontoproducemoreood.Fruits,vegetables,and

fowerscanbegrowninhightunnels.Somearmersgrowtheirproduce

organically,withoutanyagrochemicals.

Case Study: Conservation In Action

balancewithitsnaturalenvironment.Unboundedoptimism

about the future, careless disregard of natures limits and

uncertainties,uncriticalfaithinProvidence,devotiontoself-

aggrandizementallthesewerenationalaswellasregional

characteristics.

Today,decades of conservationmethods have begun topay off.

Theerosionratebywaterhasdecreased,farmersareconsistentlyusing

conservation practices, and more farmland is being enrolled in the

Conservation Reserve Programeveryyear.Thisprogram,runbythe

U.S.DepartmentofAgriculture,providestechnicalandfinancialassis-

tancetofarmersandrancherstohelpthemmanagetheirlandsinan

environmentally friendlyand cost-effectivemanner. Ithelps farmers

andranchersreducesoilerosion,provideforthenationsfoodsources,

andhelpimprovewaterquality.



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AGRiCuLTuRE

The soil conservaTion acT

HughHammond Bennett, a soil scientist andmember of President

FranklinD.Rooseveltsadministration,realizedthateveryAmericans

futurewastiedtotheplightoftheDustBowlfarmers.Itaffectedtheentirecountry,notjusttheGreatPlains.Hewantedtopreservethesoil

byreformingfarmingpractices.HebecameknownastheFatherofSoil

Conservation.

In1933,Bennettbecamethefirstdirectorofthenewlyformed

SoilErosionService,whosejobitwastofightagainsterosionand

improve farmingmethods. Through his work and efforts, the Soil

ConservationAct of 1935was passed. Its focus was on improving

farmingtechniques.

The Soil Conservation Act established the Soil Conservation

Service(SCS).Thechiefpurposeofthisagencywastodealwithissues

ofsoilerosion.Bennettwaslargelyresponsiblefortheacceptanceof

workablesoilconservationmethods.Heplayedamajorroleinconvert-

ingalargepartoftheGreatPlainsbacktograsslands.In1943,hewrote

in the Annals of the Association of American Geographers:Ifwe are

boldinourthinking,courageousinacceptingnewideas,andwillingto

workwith,insteadofagainst,ourland,weshallfindinconservation

farminganavenuetothegreatestfoodproductiontheworldhaseverknownnotonlyforthewar,butforthepeacethatistofollow.Inits

earlyyears,theSCSconductedsoilsurveysoflandaroundtheUnited

States. It also looked at other conservation problems, such as soil

salinity control.TheSCScurrentlypublishesmapsshowingareasof

soilerosionandisalsoinvolvedinthescientificresearchofpesticides.WithoutthehelpoftheSCS,Americansprobablywouldnothavecome

asfarastheyhavetodayinrehabilitatingandtakingcareoftheland.


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reneWAble And

nOnreneWAble

resOurCes

CHAPTER

3

Therearetwogeneralclassesofresources:renewableandnonrenew-

able.Thischapterfocusesonthevariousagriculturalresourcesand

the importantcycles that affect them.The relationship of these

resourceswithinthefoodchainisalsoexplored.Agriculturalresources

includingsoil,crops,livestock,andaquaticresourcesarealsoaddressed.

why some agriculTural resources are

renewaBle and some are noT

A renewable resource is a resource that can be replenished. It is a

resource that can be replaced through natural ecological cycles or

goodmanagementpractices.The oppositeof this isanonrenewable

resourcearesourcethatcannotbereplenished(onceitisgone,itisgoneforgood).Forpracticalapplications,somescientistsconsidera

renewableresourceonethatcanbereplenishedwithinonegeneration

(approximately20to30years)andanonrenewableresourceonethat

cannotbereplenishedinonegeneration.


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AGRiCuLTuRE0

For many classes of resources, it is easy to determine which

resourcesarerenewableandwhicharenot.Forexample,withenergy

resources, fossil fuels (oil, petroleum)and coal are not renewable

becausetheytookmillionsofyearstoform.Eventhoughthesamegeological processes are still happening today, these resources will

notbereplacedwithinourlifetime,sotheyareconsiderednonre-

newable. Energy resources, such as windpower andwater power,

areconsideredrenewablebecausetheyarereadilyabundantandcan

begeneratedonanearlycontinualbasis.Whenlookingat agricul-

tural resources, soilmight beconsidered a nonrenewable resource

(as discussed inChapter 1)because it takes hundreds of years to

form.Determiningwhetheragriculturalresourcesarerenewableor

nonrenewableisnotasclear-cutasforothertypesofresources,like

energy.

Agriculturalresourcesinvolveecosystems,whicharefragileand

complex.All elementsof livingsystemsare interwoven;if oneele-

mentisaffected,theentiresystemisaffected.Comparetheseinter-

actionstoacar:Acarwillworkwellaslongasalltheindividual

componentsarebeingtakencareofandfunctioningright;but,if

suddenly,oneofthepartsisneglectedandstopsworkingproperly

forexample,ifthecarrunsoutofgasitimpactstheentiresystem.Ifonecomponentstopsworkingthewayitshould,theentiresystem

isjeopardized,anduntilthatonecomponentismanagedcorrectly,

thesystemfailsorisunproductive.

AmericasawthishappenwiththeDustBowlthesoilsystem

was damaged, which triggered a chain reaction, making the land

unfarmable.Usingsoil toomuchover a longperiodof time fora

singlecropcanrobitofthespecificnutrientsneededbythatcrop.

Ifthenutrientsinthesoilareusedup,thenanycroprequiringthose

nutrientswillbe unabletogrow.If thedelicatebalanceis affected,thatcropcanbecomenonrenewable.

Another formofnonrenewabilityconcernsinvasiveplantsand

noxiousweeds.Ifanaggressiveplantorweedinfestsanarea,itcan

crowdoutnativeplantsbyusingvitalnutrientsinthesoilsothat


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RENEWAbLE ANd NoNRENEWAbLE REsouRCEs

thenativeplantscannotsurvive.Iftheinvasiveplanttakesover,the

native plant becomes nonrenewable in that area as long as those

conditionsexist.

Concerninganimals,ifthelandcannotsupportananimalpopu-lation, thentheanimalresourceisnolongeravailablein thatarea.

For example, if ranchers permit cattle to overgraze, that destroys

the soil and grass systems and prevents further grazing.The bal-

ancecanbesoupset,infact,thataprocesscalleddesertification

cantakeplace,makingtheareauninhabitableforplants,animals,

andevenpeople.

So,whilemanypeoplemaythinkthatfruits,vegetables,grains,

flowers,trees,andanimalsareautomaticallyrenewablethatisnot

necessarily so. Their availability is part of a complex system that

mustbedelicatelybalanced.Thekeytounderstandingthissystemis

tounderstandsiximportantnaturalcyclesthatexistonEarth.

The six criTical resource cycles: mainTaining

a delicaTe Balance

The six cycles that work together are thewater, nitrogen, carbon,

phosphorus,oxygen,andenergycycles.

T wt c

Waterisnecessaryforplantgrowth,fordissolvingandtransporting

plantnutrients, and for the survival of soil organisms.The water

cycleisfundamentaltoalllifeonEarth.

Froma fast-moving stream, toa rainfall, tomovementofwater

throughtheground,waterisalwaysinmotion.Theendlessmovement

andrecyclingofwaterbetweentheatmosphere,thelandssurface,and

undergroundiscalledthewatercycle,orthehydrologiccycle.

Twoseparateforcesmakethewatercyclework.TheenergyofthesunandtheforceoftheEarthsgravitydriveit.Watervaporiscar-

riedthroughtheatmospherebyaircurrents.Whentheaircools,it

condenses,formingclouds.SomeofthemoisturefallsbacktoEarth

asrain,snow,hail,orsleet.


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Once thewater reaches the ground, itcangoin several direc-

tionsbeforeitreturnsagaintotheatmosphere.Plantscanusethe

water,itcanbestoredinlakes,oritcanseepintothesoil.Thesuns

energycanthenmakethewaterevaporatebackintotheatmosphere,ortheEarthsgravitycanpullthewaterthathasenteredtheground

down through the soil to be stored for years as slowly moving

groundwater.

Groundwater can be stored in aquifers (natural underground

reservoirs)oritcaneventuallyseepintospringsandresurface.Water

on the surface is returned to theatmosphere through theprocess

ofevaporation.Waterthathasbeenusedbyplantsisreturnedto

the atmosphere as vapor through transpiration, which happens

whenwaterpassesthroughtheleavesofplants.Thesetwoconcepts

togetherarecalledevapotranspiration.Evapotranspirationisgreat-

estinareasthatarehot,dry,sunny,orwindy.

Thepresenceofwaterinagricultureandgrazingmustbewell

managed.Althoughwateriscriticalforplantgrowthandtransport-

ingnutrients,itcanalsobeadestructiveforceifnotmanagedprop-

erly.Itcancausesoilcompaction,whichclumpstheparticlesofsoil

closetogetherandremovestheimportantairspaceneededfornutri-

entstomovethroughthesoil;itcanleach(remove)nutrientsfromthesoil;andtoomuchwatercancauseexcessrunoffanderosion.

The nitroge cyle

The nitrogen cycle is the process by which nitrogen in the atmo-

sphereentersthesoilandbecomespartoflivingorganisms,before

returningtotheatmosphere.Nitrogenmakesup78%oftheEarths

atmosphere.Thisnitrogenmust,however,beconvertedfromagas

into a chemically usable formbefore living organisms can use it.

This transformation takesplace throughthe nitrogen cycle,whichtransformsthenitrogengasintoammoniaornitrates.

Mostofthenitrogenconversionprocessoccursbiologically.This

isdonebyfree-living,nitrogen-fixingbacteria;bacterialivingonthe

rootsofplants;andthroughcertainalgaeandlichens.


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Nitrogen that has been converted to ammonia and nitrates is

useddirectlybyplantsandisabsorbedintheirtissuesasplantpro-

teins.Thenitrogenthenpassesfromplantstoherbivores(plant-eat-

inganimals)andthentocarnivores(meat-eatinganimals).Whenplantsandanimalsdie,thenitrogencompoundsarebro-

kendownbydecomposingintoammonia.Someofthisammonia

isthenusedbyplants,andtherestiseitherdissolvedorheldinthe

soil.Ifitisdissolvedorheldinthesoil,microorganismsthengoto

workonitinaprocesscalled nitrification.Nitrates canbe stored

inhumusorwashedfromthesoilandcarriedawaytostreamsand

lakes.Nitratesmayalsobeconvertedandreturnedtotheatmosphere

byaprocesscalleddenitrification.

The nitrogen cycle is important because plants need nitrogen

togrow,develop, andproduce seeds.Themainsourceof nitrogen

insoilsisfromorganicmatter(humus).Bacterialivinginthesoil

convertorganicformsofnitrogentoinorganicformsthatplantscan

use.Nitrogenisthentakenupbyplantroots.Whentheplantdies,it

decaysandbecomespartoftheorganicmatterinthesoil.Theland

mustbewellmanagedornitrogencanbewashedoutofthesoil,

whichthenimpactsthegrowthofcrops.

The carbon cyle

Thecarboncycleisimportantbecausecarbonisthebasicstructural

materialforallcelllife.Carbonmakesthesoilproductive,andplants

healthy.Thecarboncycleisthemovementofcarbonbetweenthe

atmosphere,theoceans,theland,andlivingorganisms.

Theatmosphereandplantsexchangecarbon.Plantsabsorbcar-

bondioxidefromtheatmosphereduring photosynthesisandthen

releasecarbondioxidebackintotheatmosphereduringrespiration.

Another major exchange of carbon dioxide happens between theoceans and the atmosphere. The dissolved carbon dioxide in the

oceansisusedbyoceanplantsinphotosynthesis.

Carbonisalsoexchangedthroughthesoil.Cropandanimalresi-

dues decomposeandformorganicmatter,whichcontainscarbon.


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AGRiCuLTuRE

For plants to be able to use these nutrients, soil organisms break

themdowninaprocesscalledmineralization .

Animalsalsogiveoffcarbondioxidewhentheybreathe.Some

plants are eaten by grazing animals, which then return organiccarbonto thesoilasmanure.Easilybroken-downformsof carbon

inmanureandplantcellsarereleasedascarbondioxide.Formsof

carbonthataredifficulttobreakdownbecomestabilizedinthesoil

ashumus.

(A) The Water Cycle: Water repeatedly moves through the atmosphere,

ground surface, and ground subsurface to support life systems on Earth.

(B) The Nitrogen Cycle: Plant and animal wastes decompose and add nitrogen

to the soil. The bacteria in the soil converts the nitrogen into forms that plantscan use; plants use the nitrogen in the soil to grow; people and animals eat

the plants; then animal and plant residues return nitrogen to the soil again,

completing the cycle.


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(C) The Carbon Cycle: Plants take up carbon dioxide through photosynthesis.

Animals eat the plants. They then give off carbon dioxide to the atmosphere as

well as organic carbon to the soil in manure. Carbon is used by plants from the

soil through mineralization. Other carbon remains in the soil as humus.(D) The Phosphorus Cycle: Soil organisms mineralize (release) phosphorus

from organic matter. Plants use the phosphorus. Animals eat the plants.

Animals either use the phosphorus or return it to the soil.


The phoshorus cyle

Likenitrogen,phosphorusisaprimaryplantnutrient.Phosphorus

isnotpartoftheatmosphere,however.Itisfoundinrocks,miner-

als,andorganicmatterin thesoil.Chemical reactionsandactivitybymicrobes(microorganisms)inthesoilaffecttheavailabilityof

phosphorusforplantstouse.

Plants use phosphorus for energy and reproduction. Animals

consume phosphorus when they eat plants. The phosphorus that


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AGRiCuLTuRE

isnotusedtohelptheanimalgrowisreturnedtothesoilinthe

animals manure. Once the phosphorus is in the soil again, it is

decomposedbysoilorganismssothatitcanbeusedbyplantsagain,

andthecyclerepeatsitself.

Th oxygn cyl

Theoxygencyclefollowsthesamepathsasthecarboncyclebecause

oxygenispartofcarbondioxide.Oxygenisalsopresentinwater.

Oxygenisreleasedtotheatmosphereduringplantphotosynthesis.

Th enrgy cyl

Theenergycycleispoweredbysunlight,whichplantsconvertintocar-

bohydrates.Inordertocaptureasmuchsolarenergyaspossible,plants

need tobeverydense(growingclose together).The angle of leaves

alsohasaneffectontheenergytheycanabsorb.Tallerplantsareable

tocapturemoresunlight.Plantswithhorizontalleavescapturemore

sunlightthangrasseswithvertical(upright)leaves.

Energyfromplants is transferred into the soil by the deathand

decayofplantrootsandmatter,whicheventuallydecomposeenough

to become humus. During these steps, energy is being used in the

decompositionorislostasheat.Thick, green plants create a high-energy flow. When livestoc

agriculture food animals

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