Soil and - PowerPoint Presentation

Slide1

Soil and Agriculture Review Notes

Industrialized Agriculture

Soil Degradation

Overgrazing

Food Security

Green Revolution

Feedlot Agriculture

Food ChoicesSlide2

Soil: The Foundation for Sustainable AgricultureAgriculture =

practice of raising crops and livestock for human use and consumption

Cropland

=

land used to raise plants for human use

Rangeland

or

pasture

=

land used for grazing livestock

Land devoted to agriculture covers 38% of Earth’s landSlide3

Agriculture arose 10,000 years agoDifferent cultures independently invented agricultureEvidence for the earliest plant and animal domestication is from the “Fertile Crescent” of the Middle East

Agriculture rose independently in at least China, Africa, and the Americas

Raising crops was a positive feedback cycle

Harvesting the crops required people to be sedentary

Being sedentary encouraged the planting of more crops and production of more food

More crops allowed larger populations

Larger populations required planting more cropsSlide4
Slide5

Industrialized Agriculture

Traditional Agriculture- performed by humans and animal muscle power with simple tools and machines

Use of

polycultures

Subsistence agriculture- families produce enough food to feed themselves

Intensive- produce excess food to sell in market

Stops short of using fossil fuels

Industrialized Agriculture- large scale mechanization and fossil fuel combustion

Use of monocultures

Replaces horses and oxen

Cultivate, harvest, transport and process crops at higher yieldsSlide6

Industrialized Agriculture

Three systems produce most of our food

Croplands: 77%

Rangelands, pastures, and feedlots: 16%

Aquaculture: 7%

Importance of wheat, rice, and corn Slide7

Industrialized

Food Production in the

US

Industrialized agriculture uses about 17% of all commercial energy in the U.S. and food travels an average 2,400 kilometers from farm to plate.Slide8

Industrialized Agriculture

Monocultures

More efficient = increased output

Reduces biodiversity

Narrowed human diet

90% of the food consumed comes from just 15 crop species and 8 livestock species

I.A. occupies 25% of the world

’

s cropland

Intensive cultivation creates problems with the integrity of the soil

Bad soil = no crops = decrease in populationSlide9

Industrialized Agriculture

About 80% of the world

s food supply is produced by industrialized agriculture.

Uses large amounts of fossil fuel energy, water, commercial fertilizers, and pesticides to produce monocultures.Slide10

Conserving SoilFeeding the world’s rising human population requires changing our diet or increasing agricultural production

But land suitable for farming is running out

Mismanaged agriculture turns grasslands into deserts, removes forests, diminishes biodiversity and encourages the growth of non-native species

It also pollutes soil, air, and water with chemicals

Fertile soil is blown and washed away

We must improve the efficiency of food production while we decrease our impact on natural systemsSlide11

Soil Degradation

Over the past 50 years, soil degradation has reduced potential rates of global grain production by 13% on cropland and 4% on rangeland

Most degradation results from cropland agriculture, overgrazing by livestock and deforestationSlide12

Soil Degradation

Increased vulnerability through:

Over cultivating fields through poor planning or excessive tilling

Overgrazing rangelands with more livestock than land can support

Clearing forests on steep slopes or with larger clear-cutsSlide13

Soil Degradation

Soil degradation is especially severe in arid environments

Desertification

=

a form of land degradation with more than a 10% loss of productivity

Caused primarily by wind and water erosion, but also by:

Deforestation, soil compaction, and overgrazing

Drought, salinization, water depletion

Climate change

Arid and semiarid lands (

drylands

) are most prone to desertification

Cover about 40% of the Earth’s surfaceSlide14

Conserving the soilNo-till farming has many benefitsIt increases organic matter and soil biotaReduces erosion and improves soil quality

Uses less labor, saves time, causes less wear on machinery

Prevents carbon from entering the atmosphere (carbon storage)—may help mitigate climate change

Reduces fossil fuel use due to less use of the tractors

Adds organic matter to soils that is kept from the atmosphereSlide15
Slide16

No-till farming has many benefits40% of U.S. farmland uses conservation tillageErosion rates in the United States declined from 9.1 tons/ha (3.7 tons/acre) in 1982 to 5.9 tons/ha (2.4 tons/acre) in 2003

In Brazil, Argentina, and Paraguay, over half of all cropland is now under no-till cultivation

Crop yields have increased while costs have dropped

May require increased use of herbicides and fertilizers

To minimize problems:

Use

green manure

(dead plants as fertilizer)

Rotate fields with cover cropsSlide17

Overgrazing

Grazing is sustainable as long as:

Do not exceed the ranges carrying capacity

Do not consume grasses faster than they can grow back/be replaces

Overgrazing occurs when many animals eat too much plant cover

Impeding regrowth

Prevents replace of biomass

Creates positive feedback loop/cycleSlide18
Slide19

Overgrazing

Positive feedback loop- instead of stabilizing a system (negative feedback loop), they drive it further towards another extreme

When livestock remove too much plant cover, more soil is exposed and made vulnerable to erosion. Erosion makes it difficult for vegetation to regrow perpetuating the lack of cover and give rise to more erosion

Degraded soils = great home for invasive species to outcompete native plantsSlide20
Slide21

Overgrazing

Overgrazing can compact soil

Harder for water to infiltrate

Harder for soils to aerate

Harder for plant roots to expand

Harder for plants to conduct cellular respirationSlide22

Food Security

850 million people in developing countries do not have enough to eat

Political obstacles

Inefficiencies in distribution

Every 5 seconds a child starves to death

Since 1970 we have reduced world hunger from 26% to 13%

Food security is the guarantee of an adequate and reliable food supply available to all people at all timesSlide23

We face undernutrition, overnutrition, and malnutritionUndernutrition =

people receive fewer calories than their minimum requirements

Due to economics, politics, conflict, and inefficiencies in distribution

Malnutrition

- people receive fewer vitamins, minerals, proteins and/or nutrients than minimum requirements

Most undernourished live in developing nations

But 50 million Americans are “food insecure”

Food security

=

guarantee of an adequate, safe, nutritious, and reliable food supply

Undernutrition has decreased since the 1960sSlide24

We are producing more food per person The human population is expected to reach 9 billion by 2050This will mean 2 billion more people to feed

Food production has exceeded population growth over the last 50 years

We produce food through technology

Fossil fuels, irrigation, fertilizer, pesticides, cultivating more land, genetic engineering

Today, soils are in decline and most arable land is already farmedSlide25
Slide26

Green Revolution

1950

s the Green Revolution introduced to the developing world to boost agricultural production:

New technology, crop varieties and farming practices

Created from the desire for greater quantity and quality of food for the growing population

Increased yields and decreased starvation

Developing countries were able to double, triple or quadruple yieldsSlide27

The Green Revolution brought mixed consequencesDepended on heavy use of:Synthetic fertilizers and chemical pesticides Irrigation

Fossil fuel-powered machinery

From 1900 to 2000, cultivated area increased 33% while energy inputs increased 80 times

Positive effects on the environment

Prevented some deforestation and land conversion

Preserved biodiversity and ecosystemsSlide28

The Green Revolution

Lack of water, high costs for small farmers, and physical limits to increasing crop yields hinder expansion of the green revolution.

Since 1978 the amount of irrigated land per person has declined due to:

Depletion of underground water supplies.

Inefficient irrigation methods.

Salt build-up.

Cost of irrigating crops.Slide29

The Green Revolution

Modern agriculture has a greater harmful environmental impact than any human activity.

Loss of a variety of genetically different crop and livestock strains might limit raw material needed for future green and gene revolutions.

In the U.S., 97% of the food plant varieties available in the 1940 no longer exist in large quantities.Slide30

We are moving toward sustainable agricultureSustainable agriculture =

agriculture that does not deplete soils faster than they form. It does not

reduce the amount of healthy soil

pollute water

decrease genetic diversity

No-till farming and other soil conservation methods help make agriculture more sustainable

Reducing fossil-fuel inputs and pollution is a key goal

Many approaches move away from the industrial agriculture modelSlide31

Fig. 13-18, p. 285

Biodiversity Loss

Soil

Water

Air Pollution

Human Health

Loss and degradation of grasslands, forests, and wetlands

Erosion

Water waste

Greenhouse gas emissions from fossil fuel use

Nitrates in drinking water

Loss of fertility

Aquifer depletion

Pesticide residues in drinking water, food, and air

Salinization

Increased runoff and flooding from cleared land

Other air pollutants from fossil fuel use

Fish kills from pesticide runoff

Waterlogging

Sediment pollution from erosion

Greenhouse gas emissions of nitrous oxide from use of inorganic fertilizers

Contamination of drinking and swimming water with disease organisms from livestock wastes

Desertification

Killing wild predators to protect livestock

Fish kills from pesticide runoff

Surface and groundwater pollution from pesticides and fertilizers

Belching of the greenhouse gas methane by cattle

Loss of genetic diversity of wild crop strains replaced by monoculture strains

Bacterial contamination of meat

Overfertilization of lakes and rivers from runoff of fertilizers, livestock wastes, and food processing wastes

Pollution from pesticide spraysSlide32

Green Revolution

Benefit to the environment:

Used already cultivated land

Prevented some deforestation and habitat conversion

Preserved biodiversity and natural ecosystems

Harm to the environment:

Intensive application of water, fossil fuels, inorganic fertilizers and synthetic pesticides

Increases pollution, erosion, salinization and desertificationSlide33

Raising Animals for FoodSince 1950, global meat production has increased fivefold and per capita meat consumption has doubledAs wealth and commerce increase, so does meat, milk, and egg consumptionDomestic animals raised for food increased from 7.2 billion in 1961 to 27.5 billion in 2011

Meat consumption is expected to double by 2050Slide34

Feedlot Agriculture

Consuming animal products has environmental, social, agricultural and economic impacts

Domesticated animals (mostly chickens) raised for food rose from 7.3 billion to 20.6 billion between 1961 and 2000Slide35

Feedlot Agriculture

About half of the world

’

s meat is produced by livestock grazing on grass.

The other half is produced under factory-like conditions (feedlots).

Factory farms/ concentrated animal feeding operations (Densely packed livestock are fed grain or fish meal).

Half

of the world

’

s pork, poultry and beef come from feed lots

Eating more chicken and farm-raised fish and less beef and pork reduces harmful environmental impacts of meat production.Slide36
Slide37
Slide38

Feedlot Agriculture

Feedlots reduces the impact on landscape thus reducing soil degradation through overgrazing

However, feedlots are contributors to air and water pollution

Animal waste can pollute surface and groundwater

One dairy cow can produce 44,975 lbs of waste in one year

To avoid disease animals are dosed heavily with antibiotics (can create antibiotic resistance in humans)Slide39

Fig. 13-21, p. 289

Trade-Offs

Animal Feedlots

Advantages

Disadvantages

Increased meat production

Need large inputs of grain, fish meal, water, and fossil fuels

Higher profits

Concentrate animal wastes that can pollute water

Less land use

Reduced overgrazing

Reduced soil erosion

Antibiotics can increase genetic resistance to microbes in humans

Help protect biodiversitySlide40

Food Choices

It is more efficient, energy wise, to eat lower on the trophic levels than to eat meat

In 1900, 10% of global grain went to feeding animals…….In 1950 20% was used

By the beginning of the 21

st

century , we were feeding 45% of global grain production to animalsSlide41
Slide42

Efficiency of converting grain into animal protein.

Figure 13-22Slide43

Food Choices

Sustainable agriculture-

Related to low-input agriculture that uses smaller amounts of pesticides, fertilizers, growth hormones, water and fossil fuel energy

Organic agriculture

Do not use synthetic fertilizers, insecticides, fungicides or herbicides

Use biological approaches such as compostingSlide44
Slide45

Organic agriculture is boomingOrganic farmers can’t keep up with demandU.S. consumers pay $29.2 billion in 2011Worldwide sales tripled from 2000 to 2010

Production is increasing. In 2011:

Nearly 2 million ha (4.8 million acres) in the U.S.

37 million ha (91 million acres) worldwide

But still less than 1% of total agricultural land

Two-thirds of organic agricultural land is in developing nations

30% of Mexico’s coffee production is organicSlide46

Fig. 13-33, p. 302

Solutions

Sustainable Organic Agriculture

More

Less

High-yield polyculture

Soil erosion

Soil salinization

Organic fertilizers

Aquifer depletion

Biological pest control

Overgrazing

Integrated pest management

Overfishing

Loss of biodiversity

Efficient irrigation

Loss of prime cropland

Perennial crops

Crop rotation

Food waste

Water-efficient

crops

Subsidies for unsustainable farming and fishing

Soil conservation

Subsidies for sustainable farming and fishing

Population growth

PovertySlide47

Sustainable Agriculture

Results of 22 year study comparing organic and conventional farming.

Figure 13-34Slide48

Fig. 13-34, p. 302

Solutions

Organic Farming

Improves soil fertility

Reduces soil erosion

Retains more water in soil during drought years

Uses about 30% less energy per unit of yield

Lowers CO

2

emissions

Reduces water pollution from recycling livestock wastes

Eliminates pollution from pesticides

Increases biodiversity above and below ground

Benefits wildlife such as birds and batsSlide49

Sustainable Agriculture

More research, demonstration projects, government subsidies, and training can promote more sustainable organic agriculture.

Figure 13-35