CES210 Chapter Ten
CES210 Chapter Ten CES 210
Popular in Introduction to Conservation and Environmental Science
Popular in GN Natural Science
verified elite notetaker
This 5 page Class Notes was uploaded by Emma Eiden on Sunday October 9, 2016. The Class Notes belongs to CES 210 at University of Wisconsin - Milwaukee taught by Mai Phillips in Fall 2016. Since its upload, it has received 24 views. For similar materials see Introduction to Conservation and Environmental Science in GN Natural Science at University of Wisconsin - Milwaukee.
Reviews for CES210 Chapter Ten
Report this Material
What is Karma?
Karma is the currency of StudySoup.
You can buy or earn more Karma at anytime and redeem it for class notes, study guides, flashcards, and more!
Date Created: 10/09/16
CES210:ConservationandEnvironmentalScience ChapterTen: Farming: ConventionalandSustainablePractices Case Study: Farming theCerrado - Cerrado: avast area ofgrassland and tropical foreststretching from Bolivia andParaguay across thecenter of Brazil almostto the AtlanticOcean - In recent decades, Brazil hasdeveloped new varieties of soybeansspecially adapted forthesoils and climate of theCerrado - Since 2007,Brazilhas been the world’stop exporter, shipping some50 million metric tonsper year, orabout 10%morethantheUnited States WHATIS SOIL? Soils are complex ecosystems - With careful management thatprevent erosion and adds organicmaterial, soilcan be replenished andrenewed indefinitely. But mostfarming techniques deplete soil. Plowing exposes bare soilto erosion by windor water,and annualharvests removeorganicmaterial such as leaves and roots - Soil is amarvelous, complexsubstance.It is acombination ofweathered rocks, plants debris, living fungi,and bacteria, an entire ecosystem that is hidden to mostof us Soil hassix components… 1. Sand andgravel 2. Silts and clays (extremely small mineral particles) 3. Dead organic material(decaying plant matter) 4. Soil faunaand flora(living organisms,like worms,fungi,rootsof plants,and insects) 5. Water (moisturefromrainfall orgroundwater) 6. Air(tiny pocketsof air that helps bacteria andother organismssurvive) - Soil texture– theamountof sand,silt, andclay in the soil – is oneof themostimportant characteristics of soils. Texture helps determine whetherrainfalldrains away quickly orponds up and drownsplants - Reddish soils, including most tropicalsoils, often arecolored by iron-rich,rust-colored clays, which storefew nutrientsforplants.Deep black soils onthe otherhand,are rich in organic material, and thusrich in nutrients Healthy soil faunacan determine soil fertility - Soil bacteria, algae, and fungidecomposeandrecycle leaf litter, making nutrients available to plants - Manyplant species grownbest with thehelp ofparticular species ofsoil fungiin relations called mycorrhizalsymbiosis - Thehealth ofthe soilecosystem dependson environmentalconditions, including climate, topography,andparent material (themineral grains orbedrock on which soilis built), and frequently ofdisturbance - Mostsoil faunaoccurin theuppermostlayers of asoil, wherethey consumeleaf litter. This layer is knownas the“O”(organic) horizon - “A”horizon=topsoilorsurfacesoil - “B” horizonor subsoil, tendsto be richer in slays than theA; theBhorizon is below mostorganic activity Yourfoodcomes mostlyfrom theA horizon - Idealfarming soils havea think,organic-rich A horizon - Mollisols and alfisols dominatemostof thefarming regions of theUnited States HOW DOWEUSE, ABUSE, ANDCONSERVESOILS? - Only about11%ofthe earth’sland areais currently in crop production Arableland is unevenly distributed - Thebest agricultural landsoccur wheretheclimate is moderate – nottoo cold or toodry – and wherethick, fertile soils arefound - In developed countries 95%ofrecent agricultural growthin thepast century hascome froma combination ofimproved crop varieties and increased useof fertilizers, pesticides, and irrigation. Conversionofnew land to crop fields hascontributed relatively little to increased production Soil lossesthreaten farmproductivity - Agriculture bothcauses and suffersfromsoildegradation. Soil lossby erosion is theprimary concern. Every year about3 million haofcropland are madeunusablebyerosion worldwide Wind and watercausewidespread erosion - When waterwashes awayathin layer of soil, wecan it sheet erosion. When little rivulets of running watergathertogetherand cut small channels in thesoil, theprocess is called rill erosion. When rills enlarge to formbigger channels orravines thatare too large to beremoved by normaltillage operations, wecall theprocess gully erosion. - Overthepast 30years, Chinahas lost 93,000km2(squared)(aboutthesizeof Indiana)to desertification, orconversion of productiveland to desert. - Since theDust Bowlof the1920sand30s,theUSDAhasbeen encouraging farmers to plow along contoursrather thanup and downhills, to avoid planting steep slopes,to leave windbreaks,and to protect grass-lined waterwaysin fields Desertification affectsarid land soils - According to theUnited Nations,about1/3ofthe earth’s surfaceand thelivelihoods ofat least onebillion peopleare threatened bydesertification (conversionofproductivelands to desert), which contributes to foodinsecurity, famine,and poverty Irrigation is needed but can damagesoils - About2/3ofall fresh waterwithdrawnfromrivers, lakes, and groundwatersupplies is used to irrigation Roughly15%of all cropland is irrigated worldwide - Excessive wateroften results in waterlogging. Waterlogged soilis saturated withwater, and plant roots diefrom lack of oxygen.Salinization, in which salts accumulatein thesoil, occurs mainly when soils in dry climates are irrigated with salt-laden water Plants need nutrients,but not toomuch - Shortages ofnitrogen, potassium,andphosphorus,inparticular, can limit plant growth.Adding theseelements in fertilizer stimulates growthand increases crop yield - Fertilizer doesn’tneed to deprive fromthis energy-intensiveprocess.Manurefromlivestock and goodsoil management can produceyields as high as thosefromcommercial fertilizers - Excess nutrients badlyimpair waterquality. In theAmerican Corn Belt, groundwateris often unsafebecause ofhigh nitrate level Conventionalfarming uses abundantfossilfuels - Farming in industrialized countries is energy-intensive. Reliance on fossilfuels began in the 1920swiththeadoptionof tractors,and energy useincreased sharply afterWorld War II when nitrogen fertilizer madefromnaturalgas became available. Reliance on diesel and gasolineto run tractors, combines,and othermachinery has contributed to growin recent decades We can conserveand even rebuild soils - With careful husbandry,soilis arenewable resourcethat can bereplenished andrenewed indefinitely - Therice-growing cultures that depend onthese field havedeveloped management practices that return organicmaterial to thepaddyand carefully nurture thesoil Contoursand groundcoverreduce runoff - Contourplowing –plowing across thehill rather thanup and down–is oneofthe main strategies forcontrolling soilloss and waterrunoff - Terracing involves shaping theland to create level shelves of earth to hold waterand soil. The edges of theterrace are planted with soil-anchoringplant species. This is an expensive procedure, requiring either muchhand labororexpensive machinery, butit makes it possibleto farm very steep hillsides - Annualrow crops suchas corn orbeans generally causethehighest erosion rates becausethey leave soilformuch ofthe year - Covercrops suchas rye, alfalfa,orclover can also beplanted afterharvest to hold andprotect thesoil PESTSAND PESTICIDES - Every ecosystems hasproducers and consumers - Peoplein every culture haveknownthatsalt, smoke,and insect-repelling plants can keep away bothersomeorganisms andpreserve food.TheSumerians controlled insects andmites with sulfur5,000yearsago - Pesticide is a general term fora chemical that kills pests,but sometimes wealso consider chemicals that drivepests away tobe pesticides - In addition thereare chemicals aimed at particular groupsofpests. Herbicides are chemicals that kill plants; insecticides kill insects; and fungicides kill fungi Modernpesticides providebenefits butalso create health risks - Theera of syntheticorganicpesticides began in 1939whenSwisschemist PaulMuller discovered thepowerfulinsecticidal properties ofdicholro-diphenyl-trichloroethane(DDT) Organophosphatesandchlorinated hydrocarbonsaredominant pesticides - Pesticides varyin theirchemical structureandcomposition.Someare organic(carbon-based) compounds;othersare toxic metals (suchas arsenic) orhalogens (suchas bromine) - Atrazinewas themostheavily usedherbicide in theUnited States untiltherecent increase in glyphosateuse - Fumigantsare generally small molecules, such as carbon tetrachloride, ethylene dibromide, and methylbromide, whichcan bedelivered in theformof agas so that they readily penetrate soil and othermaterials - Inorganicpesticides include compoundsoftoxic elements suchas arsenic, sulfur,copper, and mercury - Naturalorganicpesticides, or“botanicals”, generally are extracted fromplants - Microbial agents andbiological controlsare living organismsortoxins derived fromthem that are used in place ofpesticides - As resistant pestsevolve, there is an ever-increasing need fornewer, better pesticides – this is called the pesticidetreadmill POPsaccumulatein remoteplaces - Persistent organicpollutants (POPs) isa collective term forthese chemicals, which are stable, easily absorbedinto fattytissues, and highly toxic Pesticides oftenimpair humanhealth - Pesticide effects onhuman health can bedivided in twocategories… 1. Acuteeffects,including poisoningand illnesses caused byrelatively high dosesand accidental exposures 2. Chroniceffects suspectedto include cancer, birth defects, immunological problems, endometriosis,neurological problems, Parkinson’sdisease,and otherchronicdegenerative diseases - TheWorld Health Organization(WHO)estimates that 25million peoplesufferpesticides poisoningand at least 20,000dieeach year. Atleast 2/3ofthis illness and death results from occupationalexposures in developing countries wherepeopleusepesticides withoutproper warning orprotectiveclothing ORGANICANDSUSTAINABLEAGRICULTURE - In general soilstay healthier with thesestrategies thanwith chemical-intensive monoculture cropping.A Swiss studyspanningtwodecades foundthataverage yields on organic plots were 20%less than on adjacentfields farmedby conventionalmethods,butcosts werelower, so that net returns to thefarmers were higherwith organiccrops - Proponentsofthesemethods arguethat sustainablemethodsare too inefficient and labor intensiveto feed large populations What does “organic” mean? - According to USDArules, productslabeled “100%organic”mustbe producedwithout hormones,antibiotics, pesticides, syntheticfertilizers, orgenetic modification.“Organic” means that at least 95%oftheingredients mustbeorganic. - Muchof theorganic food,cotton,andotherproducts webuyfromnonlocal producersnow comes fromoverseas, whereoversight can be even moredifficult than it is withinthe United States Strategic managementcan reducepests - Crop rotationsinvolves growing adifferent crop in a field each yearin a twoto six yearcycle Usefulorganisms can help us controlpests - Biological controls such as predators (wasps,ladybugs,prayingmantises)orpathogens (viruses, bacteria, fungi)can controlmanypests morecheaply andsafely than broad-spectrumsynthetic chemicals IPMuses acombination oftechniques - Integrated pest management (IPM)isaflexible, ecologically based strategy that is applied at specific times and aimed at specificcrops and pests - AlthoughIPMcan be goodalternative to chemical pesticides, it also presents environmental risks in the formofexotic organisms - Low-inputfarmssuch as thesetypically don’tturnout thequantity ofmeat ormilk that their intensive-agriculture neighborsdo, buttheir productioncosts are lowerand they get higher prices fortheir crops, sothe all-importantnet gain is often higher Consumers’choices play an important role - These arethe argumentsthat lead manypeopleto shift at least part of theirdiets to local foods. Eating locally can help sustain local businessesand farmcommunities - An even betterway to knowwhereyourfoodcomes and how it’s producedis to join community-supportedagriculture(CSA)farm.In return foran annualcontribution to local CSA farm,you’llreceive aweekly “share” ofwhateverthefarm produces Additionalterms to study:https://quizlet.com/158131853/conservation-and-environmental- science-chapter-ten-farming-conventional-and-sustainable-practices-flash-cards/
Are you sure you want to buy this material for
You're already Subscribed!
Looks like you've already subscribed to StudySoup, you won't need to purchase another subscription to get this material. To access this material simply click 'View Full Document'