soil, agriculture, and hunger. things we’ll talk about soil formation, characteristics soil...

Soil, Agriculture, and HungerSoil, Agriculture, and Hunger

Things we’ll talk aboutThings we’ll talk about

Soil formation, characteristicsSoil formation, characteristics

Soil erosionSoil erosion

Hunger and malnutritionHunger and malnutrition

Agricultural practicesAgricultural practices

Feeding the world’s hungryFeeding the world’s hungry

Soils: FormationSoils: Formation

Soil horizonsSoil horizons Soil profile Soil profile Humus Humus

O horizonLeaf litter

A horizonTopsoil

B horizonSubsoil

C horizonParent

material

Mature soil

Young soil

Immature soil

E horizonLeaching zone

R horizonbedrock

Weak humus-mineral mixture

Mosaicof closelypackedpebbles,boulders

Dry, brown toreddish-brown, with variable accumulationsof clay, calciumcarbonate, andsoluble salts

Desert Soil(hot, dry climate)

Grassland Soil(semiarid climate)

Alkaline,dark,and richin humus

Clay,calciumcompounds

mollisol

Soil Types

Acidiclight-coloredhumus

Iron andaluminumcompoundsmixed withclay

Forest litterleaf mold

Humus-mineralmixture

Light, grayish-brown, silt loam

Dark brownFirm clay

Tropical Rain Forest Soil(humid, tropical climate)

Deciduous Forest Soil(humid, mild climate)

oxisol alfisol

Laterite (a clay) - ironstone

Soil Components-What is dirt?Soil Components-What is dirt?

Inorganic mineralsInorganic minerals

Organic matterOrganic matter

Water and airWater and air

Living organismsLiving organisms

Inorganic mineralsInorganic minerals

45% of volume45% of volume

Macronutrients-nitrogen, phosphorus, potassium (NPK)-calcium, magnesium, sulfur

Macronutrients-nitrogen, phosphorus, potassium (NPK)-calcium, magnesium, sulfur

Micronutrients (trace elements)-iron, copper, zinc

Micronutrients (trace elements)-iron, copper, zinc

Limiting factorsLimiting factors

Organic MatterOrganic Matter

1-7% of volume1-7% of volume

Humus - helps retain water- helps retain water-soluble nutrients

- potassium, magnesium, ammonia- serves as food for soil organisms- provides future soil nutrients

Humus - helps retain water- helps retain water-soluble nutrients

- potassium, magnesium, ammonia- serves as food for soil organisms- provides future soil nutrients

Water and AirWater and Air

~ 50% of volume~ 50% of volume

Fills pore spacesFills pore spaces

Different soils have different pore size- sand - large- silt - medium- clay - small

Different soils have different pore size- sand - large- silt - medium- clay - small

Water for photosynthesis, air forrespiration

Water for photosynthesis, air forrespiration

Water Water

High permeability Low permeability

Living OrganismsLiving Organisms

~0.1% of volume~0.1% of volume

Bacteria, fungi, molds, nematodes,earthworms, insects, mammals

Bacteria, fungi, molds, nematodes,earthworms, insects, mammals

Actions contribute to soil fertility, porosity Actions contribute to soil fertility, porosity

Burrowing, feces, slime, secretions, death Burrowing, feces, slime, secretions, death

Soil: Determining FactorsSoil: Determining Factors

1) Parent material2) Climate3) Abrasion4) Organisms5) Topography6) Time

1) Parent material2) Climate3) Abrasion4) Organisms5) Topography6) Time

Parent MaterialParent Material

Rocks>>weathering>>inorganic minerals Rocks>>weathering>>inorganic minerals

Residual soils - develop on bare rockduring primary succession

Residual soils - develop on bare rockduring primary succession

Transported soils - deposited in areasby actions of wind, water, glaciers,humans

Transported soils - deposited in areasby actions of wind, water, glaciers,humans

Floodplain soils (1/3 of croplands)Floodplain soils (1/3 of croplands)

ClimateClimate

Weathering of parent materialWeathering of parent material

Heating, cooling, ice, rain (acidic)Heating, cooling, ice, rain (acidic)

AbrasionAbrasion

Physical breakdownPhysical breakdown

Rub rocks togetherRub rocks together

Wind, water, glaciersWind, water, glaciers

OrganismsOrganisms

Plant roots enlarge cracksPlant roots enlarge cracks

Burrowing helps aerateBurrowing helps aerate

Feces, death build up organic matterFeces, death build up organic matter

TopographyTopography

Steep areas subject to moreweathering, but reducedaccumulation

Steep areas subject to moreweathering, but reducedaccumulation

Flat areas subject to less weathering,but higher accumulation- deposits of transported soils

Flat areas subject to less weathering,but higher accumulation- deposits of transported soils

TimeTime

Period of weatheringPeriod of weathering

Soil Properties - PhysicalSoil Properties - Physical

Infiltration Infiltration

Leaching Leaching

Porosity/permeability Porosity/permeability

Texture Texture

Loam Loam

100%clay

Increasingpercentage silt

Increasingpercentage clay

0

20

40

60

80

80

60

40

20

0100%sand 80 60 40 20 100%silt

Increasing percentage sand

Water Water

High permeability Low permeability

Texture: effects on soil characteristicsTexture: effects on soil characteristics

Texture Nutrient Infiltration Water-Holding Aeration TilthCapacity Capacity

Clay Good Poor Good Poor Poor

Silt Medium Medium Medium Medium Medium

Sand Poor Good Poor Good Good

Loam Medium Medium Medium Medium Medium

Soil Properties - ChemicalSoil Properties - Chemical

pH - acidity, alkalinity1-6 acidic 7 neutral 8-14 alkaline- acidity produced by rain (pH 5.5), organic matter

breakdown, some fertilizers

pH - acidity, alkalinity1-6 acidic 7 neutral 8-14 alkaline- acidity produced by rain (pH 5.5), organic matter

breakdown, some fertilizers

Crops have pH preferencesneutral - alfalfa; acidic - corn, wheat;very acidic - potatoes

Crops have pH preferencesneutral - alfalfa; acidic - corn, wheat;very acidic - potatoes

Soil pH adjustment - lime (up), water (down)Soil pH adjustment - lime (up), water (down)

Soil ErosionSoil Erosion

Loss of soil by actions of wind, waterLoss of soil by actions of wind, water

Worldwide net loss - 23 billion tons/yr- eroding faster than it forms on 38% of croplands- 200-1000 years to produce 1 inch of soil

Worldwide net loss - 23 billion tons/yr- eroding faster than it forms on 38% of croplands- 200-1000 years to produce 1 inch of soil

U.S. losses - 18 tons/hectare/year- 0.7% per year- eroding 16 X faster than it is forming

U.S. losses - 18 tons/hectare/year- 0.7% per year- eroding 16 X faster than it is forming

Areas of serious concern

Areas of some concern

Stable or nonvegetative areas

Global Soil ErosionGlobal Soil Erosion

Soil Erosion: ContributorsSoil Erosion: Contributors

AgricultureAgriculture

Logging Logging

MiningMining

ConstructionConstruction

Poor Agricultural PracticesPoor Agricultural Practices

Farming steep slopesFarming steep slopesRemoving fence rowsRemoving fence rowsMoldboard plowing (in fall)Moldboard plowing (in fall)Overgrazing Overgrazing Farming natural waterwaysFarming natural waterwaysCompacting soil with large machinesCompacting soil with large machines

Lack of crop rotationLack of crop rotation

Dust Bowl - U.S. Great PlainsDust Bowl - U.S. Great Plains

Early 1930sEarly 1930s

Intensive agriculture & droughtIntensive agriculture & drought

Destroyed/damaged 90 million acresDestroyed/damaged 90 million acres

Led to Soil Conservation ServiceLed to Soil Conservation Service

Soil Conservation ServiceSoil Conservation Service

Natural Resources Conservation Service Natural Resources Conservation Service

Goal: encourage proper land usepractices to

1) maintain soil fertility2) control erosion

Goal: encourage proper land usepractices to

1) maintain soil fertility2) control erosion

Maintaining Soil FertilityMaintaining Soil Fertility

Organic (Natural) FertilizersOrganic (Natural) Fertilizers

Stimulate growth of decomposersStimulate growth of decomposers

Animal and plant wastesAnimal and plant wastes

More difficult to handle, applyMore difficult to handle, apply

Maintaining Soil FertilityMaintaining Soil Fertility

Inorganic Fertilizers (most U.S. soils)Inorganic Fertilizers (most U.S. soils)

NPK - may harm soil (sustained use)-low or no micronutrients- decrease soil oxygen- lower soil’s ability to produce useable N forms

NPK - may harm soil (sustained use)-low or no micronutrients- decrease soil oxygen- lower soil’s ability to produce useable N forms

May wash into water suppliesMay wash into water supplies- more readily dissolved than manure- more readily dissolved than manure

Soil Erosion ControlSoil Erosion Control

Conservation tillage- low-till or no-till

Conservation tillage- low-till or no-till


Strip cropping and contour farmingStrip cropping and contour farming


Crop rotationCrop rotation


Windbreaks and shelterbeltsWindbreaks and shelterbelts


Terracing Terracing


Not planting marginal landsNot planting marginal lands


Grass waterwaysGrass waterways


Rotational grazingRotational grazing

AgricultureAgriculture

Industrialized agriculture- mechanized- energy supplement from fossil fuels

Industrialized agriculture- mechanized- energy supplement from fossil fuels

Non-industrialized agriculture- unmechanized- energy supplement from

humans and animals

Non-industrialized agriculture- unmechanized- energy supplement from

humans and animals

Industrialized Agriculture in U.S.Industrialized Agriculture in U.S.

Nation’s largest industry

- 20% of labor force- 1 person feeds 77- reduces labor by 99%- yield 4 X higher- doubled food production in 150 years

Nation’s largest industry

- 20% of labor force- 1 person feeds 77- reduces labor by 99%- yield 4 X higher- doubled food production in 150 years

Industrialized Agriculture in U.S.Industrialized Agriculture in U.S.

Major problem- energy intensive- may require up to 9 units of

supplemental energy to produce 1 unit of food energy

- non-mechanized ag yields 3 units offood energy for each unit ofsupplemental energy (27 X better)

Major problem- energy intensive- may require up to 9 units of

supplemental energy to produce 1 unit of food energy

- non-mechanized ag yields 3 units offood energy for each unit ofsupplemental energy (27 X better)

Combating Hunger and MalnutritionCombating Hunger and Malnutrition

Producing more foodProducing more food

1) Cultivate more land1) Cultivate more land

2) Improve crop yields2) Improve crop yields

3) Catch, raise more fish & seafood3) Catch, raise more fish & seafood

Cultivating More LandCultivating More Land

Problems with 56% of potential croplands Problems with 56% of potential croplands

Remote locationRemote location

Insect infestationInsect infestation

Poor soils, lack of waterPoor soils, lack of water

High costs, no economic incentivesHigh costs, no economic incentives

Competition for other usesCompetition for other uses

Improving Crop YieldsImproving Crop Yields

Develop higher-yield varieties Develop higher-yield varieties Quickest and cheapest way

- better adapted to climate, soil conditions- wheat, rice

Quickest and cheapest way- better adapted to climate, soil conditions- wheat, rice

Problem: require more fertilizer, water,pesticides- weaker plants- seeds more costly for farmers in

developing nations

Problem: require more fertilizer, water,pesticides- weaker plants- seeds more costly for farmers in

developing nations

Catching, Raising More FishCatching, Raising More Fish

Supplies 25% of animal proteinSupplies 25% of animal protein

Increasing demand, level or decliningcatches- reached or exceeded MSY- fish not abundant, higher trophic levels- shrimp 1:75 energy ratio

Increasing demand, level or decliningcatches- reached or exceeded MSY- fish not abundant, higher trophic levels- shrimp 1:75 energy ratio

Alternatives?- krill, aquaculture

Alternatives?- krill, aquaculture

Can simply producing more foodsolve the world’s hunger andmalnutrition problem?


1) Poverty is chief cause of hunger, malnutrition

1) Poverty is chief cause of hunger, malnutrition

2) Inadequate distribution system2) Inadequate distribution system



3) Livestock gets most of the crops- enough to feed 16 billion people

3) Livestock gets most of the crops- enough to feed 16 billion people



4) Food must be of proper quality and quantity- marasmus - skinny, bloated belly

- diet low in calories and protein- kwashiorkor - entire body bloated

- diet high in calories, low in protein

4) Food must be of proper quality and quantity- marasmus - skinny, bloated belly

- diet low in calories and protein- kwashiorkor - entire body bloated

- diet high in calories, low in protein



5) Food must be culturally acceptable5) Food must be culturally acceptable

Alternatives to producing more foodAlternatives to producing more food

1) Simplifying diets2) Use and waste less food, fertilizer3) Use new, unconventional, enriched,

and fabricated foods4) Reduce crop losses from pests,

diseases

1) Simplifying diets2) Use and waste less food, fertilizer3) Use new, unconventional, enriched,

and fabricated foods4) Reduce crop losses from pests,

diseases

Simplifying DietsSimplifying Diets

Eating lower on the food webEating lower on the food web 1/3 of world grain production used to support

meat diets of people in developed nations

1/3 of world grain production used to support meat diets of people in developed nations

U.S. citizens eat 25 X more meat than people in developing nations

U.S. citizens eat 25 X more meat than people in developing nations

75% of N. Amer. grain goes to cattle (<5% in developing nations)

75% of N. Amer. grain goes to cattle (<5% in developing nations)

Eliminate U.S. feedlots - food for 400 million people

Eliminate U.S. feedlots - food for 400 million people

10% meat reduction - 60 million people 10% meat reduction - 60 million people

Use, Waste Less FoodUse, Waste Less Food

Wasted food - cafeterias, homes, etc.Wasted food - cafeterias, homes, etc.

Overnutrition - 30-50% of adults, 10% of children

Overnutrition - 30-50% of adults, 10% of children

Fertilizer use on non-ag land- food for 65 million

Fertilizer use on non-ag land- food for 65 million

Pets - food for 21 million

Pets - food for 21 million

New, Unconventional, Enriched, Fabricated FoodsNew, Unconventional, Enriched, Fabricated Foods

80,000 edible plants, 175 cultivated,- 16 important, 3 “biggies”

- corn, wheat, rice

80,000 edible plants, 175 cultivated,- 16 important, 3 “biggies”

- corn, wheat, rice

New crop plants - winged bean, ye-edNew crop plants - winged bean, ye-ed

Unconventional foods - insects!- high protein

Unconventional foods - insects!- high protein


Enriched foods- combat malnutrition, disease, by

adding vitamins, minerals- salt with iodine - goiter- rice with vitamin B1 - beriberi

Enriched foods- combat malnutrition, disease, by

adding vitamins, minerals- salt with iodine - goiter- rice with vitamin B1 - beriberi

Problem: added during processing,may be unavailable to those whogrow your own

Problem: added during processing,may be unavailable to those whogrow your own


Fabricated foods- substitute plant products for animal

- margarine for butter- veg. oil for lard- imitation bacon (soybeans, wheat)- soy burgers (soybeans, edible mold)

- high protein

Fabricated foods- substitute plant products for animal

- margarine for butter- veg. oil for lard- imitation bacon (soybeans, wheat)- soy burgers (soybeans, edible mold)

- high protein

Reduce Crop Losses from Pests, DiseasesReduce Crop Losses from Pests, Diseases

45% of potential crops destroyed each year- 33% before harvest- 12% during storage

45% of potential crops destroyed each year- 33% before harvest- 12% during storage

More use of pesticides needed?- similar losses in U.S. where pesticide

use is high and other countries whereuse is low

More use of pesticides needed?- similar losses in U.S. where pesticide

use is high and other countries whereuse is low

Pesticide ProblemsPesticide Problems

Persistence Persistence

Bioaccumulation/biomagnification- DDT and the bald eagle

Bioaccumulation/biomagnification- DDT and the bald eagle

Nonspecificity Nonspecificity

Development of resistanceDevelopment of resistance

Biological Controls: AlternativesBiological Controls: Alternatives

Predators or parasitesPredators or parasites

Attractants (pheromones = sex hormones)Attractants (pheromones = sex hormones)

Sterilization Sterilization

Resistant crops (genetic)Resistant crops (genetic)

soil, agriculture, and hunger. things we’ll talk about soil formation, characteristics soil...

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soil organisms

soil formation

soil fertility

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hunger slide

future soil nutrients

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