soils and agriculture. soils origins importance maturity and horizons variations with climate...
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Soils and agricultureSoils and agriculture
SoilsSoilsOriginsOrigins
ImportanceImportance
Maturity and HorizonsMaturity and Horizons
Variations with Climate and Variations with Climate and BiomesBiomes
Variations in Texture and PorosityVariations in Texture and Porosity
OriginsOrigins
ImportanceImportance
Maturity and HorizonsMaturity and Horizons
Variations with Climate and Variations with Climate and BiomesBiomes
Variations in Texture and PorosityVariations in Texture and Porosity
Soil isn’t dirt!Soil isn’t dirt!
• Soil is a complex mixture covering most of Soil is a complex mixture covering most of Earth’s land surfacesEarth’s land surfaces– Eroded rockEroded rock– Mineral nutrientsMineral nutrients– Decaying organic matterDecaying organic matter– WaterWater– AirAir– Community of organismsCommunity of organisms
• Is the basis for life and foodIs the basis for life and food
Soils have layersSoils have layers• Soils have horizontal layers called HorizonsSoils have horizontal layers called Horizons• Top 2 layers teem with plant roots and Top 2 layers teem with plant roots and
complex food webscomplex food webs– O HorizonO Horizon
• Surface litter layerSurface litter layer• Freshly fallen partly decomposed leaves etcFreshly fallen partly decomposed leaves etc
– A HorizonA Horizon• Topsoil: Most important layer for agricultural purposesTopsoil: Most important layer for agricultural purposes
– Humus: partially decomposed organic matterHumus: partially decomposed organic matter– Holds water and nutrients taken up by plantsHolds water and nutrients taken up by plants– Inorganic particlesInorganic particles– Decomposers (bacteria, fungi) breakdown organinic Decomposers (bacteria, fungi) breakdown organinic
matter releasing nutrients usable by plantsmatter releasing nutrients usable by plants– Color: Dark = Nutrient rich, Light = Nutrient poorColor: Dark = Nutrient rich, Light = Nutrient poor
Soils have layersSoils have layers
• Lower horizons contain most of a soil’s Lower horizons contain most of a soil’s inorganic material (broken down rock)inorganic material (broken down rock)– B horizonB horizon
•SubsoilSubsoil
•Varied mixture of sand, silt clay and gravelVaried mixture of sand, silt clay and gravel
– C HorizonC Horizon•Parent materialParent material
•Lies on top of bedrockLies on top of bedrock
Soil and hydrologySoil and hydrology
• Pore spaces in soil trap water and air Pore spaces in soil trap water and air needed by plant rootsneeded by plant roots– Infiltration: downward movement of Infiltration: downward movement of
water into spaces within the soilwater into spaces within the soil– Leaching: Dissolution of organic matter Leaching: Dissolution of organic matter
and nutrients in upper layers which and nutrients in upper layers which carries these materials down to the carries these materials down to the lower layerslower layers
Soil texture and porositySoil texture and porosity
• Soil textureSoil texture– Determined by relative amounts of clay, silt, Determined by relative amounts of clay, silt,
sand and gravel in the soil mixturesand and gravel in the soil mixture
• Texture determines soil porosity and Texture determines soil porosity and permeabilitypermeability– Porosity:Porosity: The volume of pore space in a soil The volume of pore space in a soil
• Larger particles = more pore spaceLarger particles = more pore space
• Smaller particles = less pore spaceSmaller particles = less pore space
– Permeabilty:Permeabilty: Rate at which water and air move Rate at which water and air move from the top layers to the lower layers of soilfrom the top layers to the lower layers of soil
Soil Profiles in Different Soil Profiles in Different BiomesBiomes
Fig. 4-27, p. 75
Why do we use grasslands for agricultural purposes?
To feed the world….To feed the world….• Conservation of matterConservation of matter
– Available resources limit agricultural productionAvailable resources limit agricultural production– Nutrients used by plantsNutrients used by plants
• Nitrates: Protein and DNANitrates: Protein and DNA• Phosphates: DNA, RNA, ATPPhosphates: DNA, RNA, ATP
– Soil degraded as nutrients removed by harvestSoil degraded as nutrients removed by harvest• Conservation of EnergyConservation of Energy
– Trophic level energy lossTrophic level energy loss• Vegetarian vs Carnivorous dietsVegetarian vs Carnivorous diets
• Green revolutionGreen revolution– Increase yield per acreIncrease yield per acre– MonocultureMonoculture– Intensive tillage = soil erosionIntensive tillage = soil erosion– Requires Requires
• Energy: Emissions and oilEnergy: Emissions and oil• Fertilizers and pesticides: Toxic pollution, soil salinizationFertilizers and pesticides: Toxic pollution, soil salinization• Irrigation: Water rights and usageIrrigation: Water rights and usage
2,000
1,500
1,000
500
0
Gra
in p
rod
uct
ion
(mill
ion
s o
f to
ns)
1950 1960 1970 1980 1990 2000 2010
Total World Grain Production
Year
400
350
300
250
150
Per
cap
ita
gra
in p
rod
uct
ion
(kilo
gra
ms
per
per
son
)
1950 1960 1970 1980 1990 2000 2010
World Grain Production per Capita
200
Year
Cal
ori
es p
er d
ay p
er p
erso
n3,700
3,500
3,300
3,100
2,900
2,700
2,500
2,300
2,100
1960
1970
1980
1990
2000
2010
2030
Year
Developed countries
World
Developing countries
Figure 14-3Figure 14-3Page 276Page 276
Croplands
• Help maintain water flow and soil infiltration
• Provide partial erosion protection • Can build soil organic matter
• Store atmospheric carbon
• Provide wildlife habitat for some species
Ecological Services Economic Services
• Food crops
• Fiber crops
• Crop genetic resources
• Jobs
Natural Capital
Croplands
Ecological Services
Economic Services
•Help maintain water flow and soil infiltration
•Provide partial erosion protection
•Can build soil organic matter
•Store atmospheric carbon
•Provide wildlife habitat for some species
•Food crops
•Fiber crops
•Crop genetic resources
•Jobs
Biodiversity Loss
Loss and degradation of habitat fromclearing grasslands and forests anddraining wetland
Fish kills from pesticide runoff
Killing of wild predators to protectlivestock
Loss of genetic diversity fromreplacing thousands of wild cropstrains with a few monoculture strains
Soil
Erosion
Loss of fertility
Salinization
Waterlogging
Desertification
Air Pollution
Greenhouse gas emissions from fossilFuel issue
Other air pollutants from fossil fuel use
Pollution from pesticide sprays
WaterWater waste
Aquifer depletion
Increased runoff andflooding from land clearedto grow crops
Sediment pollution fromerosion
Fish kills from pesticiderunoff
Surface and groundwaterpollution from pesticidesand fertilizers
Overfertilization of lakesand slow-moving riversfrom runoff of nitrates and phosphates fromfertilizers, livestockwastes, and foodprocessing wastes
Human Health
Nitrates in drinking water
Pesticide residues in drinking water,food, and air
Contamination of drinking andswimming water with disease organisms from livestock wastes
Bacterial contamination of meat
4% 2% 6% 5%
17% of totalcommercialenergy use
Crops Livestock Food processing Food distribution and preparation
Food production
Figure 14-10Figure 14-10Page 283Page 283
ConsequencesCauses
Worsening drought
Famine
Economic losses
Lower living standards
Environmentalrefugees
Overgrazing
Deforestation
Erosion
Salinization
Soil compaction
Natural climate change
Figure 14-12Figure 14-12Page 283Page 283
Reduce irrigation
Switch to salt-tolerant crops(such as barley, cotton, sugar beet)
Prevention
Flushing soil(expensive andwastes water)
Not growing crops for 2-5 years
Installing under- ground drainagesystems (expensive)
Cleanup
Solutions
Soil Salinization
Figure 14-13Figure 14-13Page 284Page 284
Reduces erosion
Saves fuel
Cuts costs
Holds more soil water
Reduces soil compaction
Allows several crops per season
Does not reduce crop yields
Reduces CO2
release from soil
Can increase herbicide use for some crops
Leaves stalks that can harbor crop pests and fungal diseases and increase pesticide use
Requires investment in expensive equipment
DisadvantagesAdvantages
Trade-Offs
Conservation Tillage
FigurFigure e 14-14-14a14aPage Page 285285
(a) Terracing
FigurFigure e 14-14-14b14bPage Page 285285
(b) Contour planting and strip cropping
FigurFigure e 14-14-14c14cPage Page 285285
(c) Alley cropping
FigurFigure e 14-14-14d14dPage Page 285285
(d) Windbreaks
Trade-Offs
Inorganic Commercial Fertilizers
Advantages Disadvantages
Do not add humus to soil
Reduce organic matter in soil
Reduce ability of soil to hold water
Lower oxygen content of soil
Require large amounts ofenergy to produce,transport, and apply
Release the greenhouse gas nitrous oxide (N2O)
Runoff can overfertilizenearby lakes and kill fish
Easy to transport
Easy to store
Easy to apply
Inexpensive to produce
Help feed one of every three people in theworld
Without commercialinorganic fertilizers,world food output coulddrop by 40% FigurFigur
e e 14-14-1515Page Page 286286
DO
NO
T P
OS
T T
O I
NT
ER
NE
T
Table 23-1Table 23-1Page 520Page 520
Table 23-1 Major Types of Pesticides
Type
Insecticides
Chlorinatedhydrocarbons
Organophosphates
Carbamates
Botanicals
Microbotanicals
Examples
DDT, aldrin, dieldrin, toxaphene, lindane, chlordane, methoxychlor, mirex
Malathion, parathion, diazinon, TEPP, DDVP,mevinphos
Aldicarb, carbaryl (Sevin), propoxur,maneb, zineb
Rotenone, pyrethrum, and camphorextracted from plants, synthetic pyrethroids (variations of pyrethrum), rotenoids (variations of rotenone), and neonicotinoids(variations of nicotine)
Various bacteria, fungi, protozoa
Persistence
High (2–15 years)
Low to moderate (1–2 weeks), but some can last several years
Low (days to weeks)
Low (days to weeks)
Low (days to weeks)
Biologically Magnified?
Yes
No
No
No
No
Table 23-1Table 23-1Page 520Page 520
Table 23-1 Major Types of Pesticides
Type
Herbicides
Contact chemicals
Systemic chemicals
Soil sterilants
Fungicides
Various chemicals
Fumigants
Various chemicals
Examples
Atrazine, simazine, paraquat
2,4-D, 2,4,5-T, Silvex, diuron,daminozide (Alar), alachlor (Lasso),glyphosate (Roundup)
Tribulan, diphenamid, dalapon, butylate
Captan, pentachlorophenol, zeneb, methyl bromide, carbon bisulfide
Carbon tetrachloride, ethylene dibromide, methyl bromide
Persistence
Low (days to weeks)
Mostly low(days to weeks)
Low (days)
Most low (days)
Mostly high
Biologically Magnified?
No
No
No
No
Yes (for most)
FigurFigure e 23-423-4Page Page 523523
600
500
400
300
200
100
1950 1950 1950 1950 1950 1950
Nu
mb
er o
f g
enet
ical
ly r
esis
tan
t in
sect
sp
ecie
s
Year
Neonicotinoids(1995)
Pyrethroids (1978)
Carbamates (1972)
Organophosphates (1965)
DDT/cyclodienes (1946)
Figure 23-7Figure 23-7Page 528Page 528
MH
MH
JH
MH
JH
JH
MH
Pupa
Eggs
Larva
Black
Producing and eating meatProducing and eating meat
• Land use issuesLand use issues– More land neededMore land needed
•More land needed for grazing than grain More land needed for grazing than grain productionproduction
•Acre of grain for human consumption feeds Acre of grain for human consumption feeds more than an acre used for grazingmore than an acre used for grazing
•Land needed to grow forage AND raise Land needed to grow forage AND raise animals: Housing, food storage and waste animals: Housing, food storage and waste disposaldisposal
Producing and eating meatProducing and eating meat• Energy issuesEnergy issues
– Eating at a lower trophic levelEating at a lower trophic level• More solar energy available to humans, less lost More solar energy available to humans, less lost
through trophic transferthrough trophic transfer
– Storage of grain less energetically expensive Storage of grain less energetically expensive than processing and storing meatthan processing and storing meat• Transport, slaughter and refrigerationTransport, slaughter and refrigeration
– Energy costs associated with meat productionEnergy costs associated with meat production• Producing grain for livestockProducing grain for livestock
– Fertilizers, irrigation, pesticides, farm machineryFertilizers, irrigation, pesticides, farm machinery
• Animal waste managementAnimal waste management– Pumping, treatment, transport, disposalPumping, treatment, transport, disposal
• Animal care and round up of free range livestockAnimal care and round up of free range livestock
Problems and consequencesProblems and consequences
• ProblemProblem– OvergrazingOvergrazing
– Water PollutionWater Pollution• SlaughterSlaughter• WastesWastes• Riparian grazingRiparian grazing
– Land useLand use• Fencing, deforestationFencing, deforestation
– Uses more waterUses more water
• ConsequenceConsequence– Desertification, erosion Desertification, erosion
nutrient lossnutrient loss
– Groundwater Groundwater contamination, ^BOD, contamination, ^BOD, Eutrophication, etcEutrophication, etc
– Habitat loss & Habitat loss & fragmentation, decreased fragmentation, decreased biodiversitybiodiversity
– Water shortages / depletionWater shortages / depletion
Eating less meat: Pro and Eating less meat: Pro and ConCon• AdvantagesAdvantages
– Reduced risk of diseaseReduced risk of disease• CholesterolCholesterol
– Clogged arteriesClogged arteries– HypertensionHypertension– Heart diseaseHeart disease
– Reduced chemical Reduced chemical exposureexposure
• HormonesHormones• SteroidsSteroids• AntibioticsAntibiotics• Pesticides (Biomag!)Pesticides (Biomag!)
– Reduced exposure to Reduced exposure to diseasedisease
• Mad CowMad Cow• Salmonella/ E. coliSalmonella/ E. coli• ParasitesParasites
• DisadvantagesDisadvantages– Meat an excellent source Meat an excellent source
of proteinof protein• Essential amino acidsEssential amino acids
– Rice and Beans!Rice and Beans!• Difficult to get enough Difficult to get enough
protein without meatprotein without meat– Nutritional deficienciesNutritional deficiencies
• Kwashikor: ProteinKwashikor: Protein• Blindness: Vit. ABlindness: Vit. A• Pollegra: Vit. BPollegra: Vit. B• Anemia: IronAnemia: Iron• Inadequate essential fats Inadequate essential fats
balancebalance
Spotter airplane
Fish farmingin cage
Trawlerfishing
Purse-seinefishing
sonartrawl flap
trawllines
trawl bag
Long line fishing
lines withhooks
Drift-net fishing
fish caughtby gills
float buoy
fish school
100
80
60
40
20
01950 19701960 200019901980
Cat
ch(m
illio
ns
of
met
ric
ton
s)
Year
Total World Fish Catch
25
20
15
10
5
01950 19701960 200019901980
Per
cap
ita
catc
h(k
ilog
ram
s p
er p
erso
n)
Year
World Fish Catch Per Person
800
600
400
200
01960 1970 1980 1990 2000
Year
80
70
60
50
40
30
20
Har
vest
(th
ou
san
ds
of
met
ric
ton
s)
Ab
un
dan
ce(k
ilog
ram
s/to
w)
Abundance
Harvest
10
Highly efficient
High yield in smallvolume of water
Increased yieldsthrough cross-breeding and genetic engineering
Can reduce over-harvesting of conventional fisheries
Little use of fuel
Profit not tied to price of oil
High profits
Advantages
Large inputs of land, feed, And water needed
Produces large and concentrated outputs of waste
Destroys mangrove forests
Increased grain productionneeded to feed some species
Fish can be killed by pesticide runoff from nearby cropland
Dense populations vulnerable to disease
Tanks too contaminated touse after about 5 years
Disadvantages
Trade-Offs
Aquaculture
What are GMOs and how What are GMOs and how are they producedare they produced
Online activitiesOnline activities
ProjectedDisadvantages
Need less fertilizer
Need less water
More resistant to insects,plant disease, frost, anddrought
Faster growth
Can grow in slightly saltysoils
Less spoilage
Better flavor
Less use of conventionalpesticides
Tolerate higher levels ofpesticide use
Higher yields
ProjectedAdvantages
Trade-OffsGenetically Modified Food and Crops
Irreversible andunpredictable genetic and ecological effects
Harmful toxins in foodFrom possible plant cellMutations
New allergens in food
Lower nutrition
Increased evolution ofPesticide-resistantInsects and plant disease
Creation of herbicide-Resistant weeds
Harm beneficial insects
Lower genetic diversity