chapter 12 food, soil & pest management tutorial by sharon ashworth & paul rich ©...

Chapter 12Chapter 12

Food, Soil & Pest Food, Soil & Pest ManagementManagement

tutorial by Sharon Ashworth& Paul Rich

© Brooks/Cole Publishing Company / ITP

OUTLINEOUTLINE

1. Food production1. Food production

2. World food supply2. World food supply

3. Increasing food production3. Increasing food production

4. Environmental impacts4. Environmental impacts

6. Sustainable agriculture6. Sustainable agriculture


1. Food Production1. Food ProductionWhat are the

patterns of the locations of the world’s principal types of food production?

1. Types of Food Production1. Types of Food Production• What are the key

features of Industrialized agriculture?

• Uses large amountsof fossil fuel, water, commercial fertilizers, & pesticides to produce huge quantities of single crops or livestock.

Types of Food ProductionTypes of Food ProductionWhat are the key features

of Traditional Agriculture?

• 1) Traditional subsistence:

• Uses primarily human labor & draft animals to produce enough crops or livestock for a family’s survival.

Types of Food ProductionFood Production

• Traditional Agriculture:

• 2) How was Traditional intensive achieved?

• Increased inputs of labor, fertilizer, & water to achieve higher yields for sale.

Food ProductionFood Production• What was the Green Revolution?

• An agricultural system that produces more food on less land (increased yields per unit area of cropland). This system has three main components:

• 1) developing & planting monocultures of genetically engineered, high–yield varieties of crops;

• 2) growing & protecting crops with large inputs of fertilizer, pesticides, & water;

• 3) increasing the intensity & frequency of cropping.

2. World Food Supply2. World Food Supply

• Do we produce enough food to feed the world?

• There is currently enough food produced to feed all people, but it is unevenly distributed.

• Many people in developing countries are undernourished or malnourished & many people in developed countries are overnourished & waste large amounts of food.

World Food SupplyWorld Food Supply

• Carrying capacity of the earth

• What is the number of people the earth can support is dependent upon?

• the cultural carrying capacity per person; (myfootprint.com)

• the sustainability of future food production;

• the percentage of the population eating meat.

World Food SupplyWorld Food Supply

• Why is food production per capita slowing?

• world population increasing;

• increasing affluent demand for food, especially meat;

• degradation & loss of cropland;

• water supply for irrigation limited;

• declining fertilizer use.

3. Increasing Food Production3. Increasing Food Production

• How can crop yields be increased?• By genetic engineering we can:• raise the share of photosynthetic product in the

seed;• develop strains of plants that are resistant to

disease, insects, & drought.• By increasing inputs of water, fertilizer, &

pesticides• eventually these additions produce no additional

increase in crop yields.

Increasing Food ProductionIncreasing Food Production

• How can new types of food can be used?

• cultivation of less widely known plants;

• cultivation of perennial plants reduce inputs of water, fertilizer, & energy – reduce soil erosion;

• yummy insects.

Increasing Food ProductionIncreasing Food ProductionBy cultivating more land?By cultivating more land?

Increasing Food ProductionIncreasing Food Production• How about cultivating more land?1) Tropical forests are being rapidly cleared• nutrient–poor soils will likely make agriculture

unsustainable;• removal of valuable carbon sink (CO2 removal)• loss of biodiversity.2) We irrigate arid (dry) lands• expensive dams;• depletion of groundwater supplies pumped up.• irrigation leaves mineral residues that eventually ruin the

land for future generations.A major economically profitable & environmentally sustainable

expansion of cropland is unlikely over the next few decades.

4. Environmental Impacts4. Environmental Impacts

• General Considerations• world population increase will demand

greater food production;• further application of green revolution

techniques will increase food production, but these techniques have limitations & environmental consequences;

• industrialized agriculture has a greater harmful impact on air, soil, water, & biodiversity resources than any other human activity.

Environmental ImpactsEnvironmental Impacts

Environmental ImpactsEnvironmental Impacts

• Focus on meat

• more than 1/2 of the world’s cropland is used to produce livestock feed;

• overgrazing is the major cause of desertification of arid & semi–arid lands;

• cattle produce methane (CH4), a greenhouse gas;

• cattle crowded into feedlots require large doses of antibiotics.

6. Sustainable Agriculture6. Sustainable Agriculture

• Some of the methods used in sustainable agriculture:

• reduce water waste in irrigation;

• increase use of organic fertilizers;

• emphasize biological pest control & integrated pest management;

• increase use of soil conservation techniques.

14-6 Soil Erosion & Degradation14-6 Soil Erosion & Degradation

What are the problems of soil erosion? • losing topsoil makes soil less fertile & less

able to hold water• while soil is a potentially renewable

resource, it takes long periods of time to form topsoil, typically 200–1000 years to form 2.5 centimeters (1 inch) of topsoil

• topsoil is eroding faster than it forms in about one–third of the world's cropland.

Soil Erosion & Degradation Soil Erosion & Degradation Fig.14–17


Why are some areas not threatened by soil erosion?

The American Dust Bowl

When did this occur?

• 1930s Great Depression

What caused it?

• Land left plowed during winter winds.

• Extended drought from 1926-1934

How did U.S. respond?

• 1935 Soil Erosion Act established Soil Conservation Districts

Regions of Desertification(Analyze Cashmere Article)

DesertificationWhat are seven causes?

• overgrazing; can you say cashmere?

• deforestation & devegetation;

• surface mining;

• poor irrigation techniques;

• salt buildup;

• farming on unsuitable terrain;

• soil compaction by farm machinery.

Can Irrigation Ruin Land?Can Irrigation Ruin Land?

What are the 2 problems with irrigation?1. Salinization results in irrigated cropland where salts build

up to levels that decrease yields or prevent cultivation.Where does the salt come from?Irrigation waters carry minerals dissolved during runoff and

through irrigation canals. These are left in the soil when plants use the water or it evaporates. Salts build up.

What is the second problem that goes with salinization?2. Waterlogging results when excess irrigation water raises

the water table & lowers crop productivity.How does this affect the vegetation?The excess irrigation was meant to wash salts away by

leaching them down deep into the soil. If the soil is waterlogged the salt comes right back up into the root zone to interfere with growth.

Salinization in Europe

Salinization• Salinisation, also known as alkalisation or sodification, is often associated with

irrigated areas where low rainfall, high evapotranspiration rates or soil textural characteristics impede the washing out of the salts which subsequently build-up in the soil surface layers. Irrigation with high salt content waters dramatically worsens the problem.

In coastal areas, salinisation can be associated with the over exploitation of groundwater caused by the demands of growing urbanisation, industry and agriculture. Over extraction of groundwater can lower the normal water table and lead to the intrusion of marine water. Natural disasters in coastal areas, such as tsunamis, can cause severe salinisation problems with several years of low fertility of the affected soil before recovery. In Nordic countries, the de-icing of roads with salts can lead to localised salinisation.

Salinity is one of the most widespread soil degradation processes on the Earth. According to some estimates, the total area of salt affected soil is about one billion hectares. They occur mainly in the arid–semiarid regions of Asia, Australia and South America. In Europe, salt affected soil occurs in the Caspian Basin, the Ukraine, the Carpathian Basin and the on the Iberian Peninsula. Soil salinity affects an estimated 1 million hectares in the European Union, mainly in the Mediterranean countries, and is a major cause of desertification. In Spain 3% of the 3.5 million hectares of irrigated land is severely affected, reducing markedly its agricultural potential while another 15 % is under serious risk.

Irrigation Problems

14-7 Match the Soil Conservation Terms: crop rotation, conservation-tillage, terracing, contour farming, strip cropping, alley cropping, organic fertilizer, green manure

• minimizes soil disturbance by use of special tillers or by no–till methods that inject seeds, fertilizers, & herbicides in unplowed soil

• protects steep slopes by creating flat sections on hillsides that retain water and soil.

• Natural fertilizers of animal & plant wastes.• follows natural land contours to control runoff; • maintains alternating rows of different vegetation between crops

that completely covers the soil.• grows crops between rows of trees• plant matter, & compost used as fertilizer • by planting crops that restore nutrients & decreases need of

inorganic fertilizers and helps to restore fertility.

1. Types of Pesticides1. Types of Pesticides

Pesticides are chemicals used to kill undesirable organisms

• insecticides: insect killers

• herbicides: plant killers

• fungicides: fungus killers

• nematocides: round–worm killers

• rodenticides: rat & mouse killers


Types of PesticidesTypes of Pesticides

1st generation pesticides– mostly natural substances obtained from plants

– examples include pyrethrum & rotenone

2nd generation pesticides– synthetic organic chemicals developed since 1945

Broad–spectrum: toxic to many species

Selective: toxic to a narrowly defined group

Persistent: remain in the environment for an extended period of time


Use of PesticidesUse of Pesticides

• Most pesticide use is in developed countries

• 90% of insecticides & 80% of herbicides applied to crops in the U.S. are used for growing cotton & corn

• the U.S. lawn is doused with10x more pesticides per hectare than cropland


FIFRA

Pages 568 to 570

What is FIFRA?

What are the key points of FIFRA?

What are the weaknesses of FIFRA?

What are suggestions for improvement?

1996 Food Quality Protection Act

Page 571

What are the key elements of this act?

2. The Case For Pesticides2. The Case For Pesticides

• pesticides save human lives– pesticides kill disease–carrying insects

• pesticides increase food supplies & lower costs

– approximately 55% of the world’s food supply is lost to pests

• pesticides increase profits for farmers– use of pesticides increases crop yields

• pesticides work faster & better than alternatives

• new pesticides are used at low rates© Brooks/Cole Publishing Company / ITP

3. The Case Against Pesticides3. The Case Against PesticidesThe pesticide treadmill

1) Use of pesticides on a crop

2) Pests develop genetic resistance to pesticides

3) Dosage of pesticides increased or new pesticide is used

4) Pests develop genetic resistance to pesticides

5) repeat


The Case Against PesticidesThe Case Against PesticidesThe pesticide treadmill – genetic resistance

Insects breed rapidly & within 5–10 years can develop immunity to pesticides through natural selection

Since 1950 at least 520 insects & mites, 273 weeds, 150 plant diseases, & 10 rodents have developed genetic resistance to one or more pesticides

Farmers Cope With Roundup-Resistant Weeds

http://www.nytimes.com/2010/05/04/business/energy-environment/04weed.html?pagewanted=all&_r=0

(see Fig. 21–3)


The Case Against PesticidesThe Case Against PesticidesThe pesticide treadmill – natural predators

• broad–spectrum insecticides also kill the natural predators & parasites of the target insect

• disappearance of predators allows previously unproblematic insects to become pests


The Case Against PesticidesThe Case Against PesticidesThe pesticide treadmill

Although the use of synthetic pesticides has increased 33x since 1942, it is estimated that more of the U.S. food supply is lost to pests today than in the 1940s. Losses attributed to insects have almost doubled.


The Case Against PesticidesThe Case Against Pesticides

Pesticides & Wildlife

• less than 2% of an insecticide applied by aerial or ground spraying reaches its target

• the chemicals end up in air, surface water, groundwater, food, & non–target organisms

• some pesticides biomagnify in food webs, poisoning or affecting the reproduction of top carnivores

• some pesticides run off into water bodies, harming aquatic animal & plant life


Cultivation practices

• crop rotation

• planting trap crops

• adjusting planting times

• intercropping & polyculture

• plantings to attract predators

4. Other Methods of Pest Control4. Other Methods of Pest Control


Other Methods of Pest ControlOther Methods of Pest Control

Genetic engineering

• development of disease & pest resistant crop varieties

• could reduce the number & quantity of pesticides needed to protect crops

Potential limitations

• eventual pest adaptation to new crops

• resistance factors may be toxic to beneficial insects & other animals


Other Methods of Pest ControlOther Methods of Pest ControlBiopesticides, Hormones, & Birth Control

Biopesticides:

• plant toxins synthesized for mass production

• microbes toxic to plants

• Beneficial parasites http://news.nationalgeographic.com/news/2010/07/100719-parasites-wasps-bugs-cassava-thailand-science-environment/

Hormones:

• phermones to lure pests into traps

Birth control:

• release of sterile males


http://news.nationalgeographic.com/news/2010/07/100719-parasites-wasps-bugs-cassava-thailand-science-environment/

http://news.nationalgeographic.com/news/2010/07/100719-parasites-wasps-bugs-cassava-thailand-science-environment/

Other Methods of Pest ControlOther Methods of Pest Control

Integrated Pest Management

Each crop & its pests are evaluated as parts of an ecological system. A control program is developed that includes a mix of cultivation, biological & chemical control methods.

1) crops monitored for damaging levels of pests

2) biological control methods used

3) small amounts of diverse chemicals used to prevent development of resistance & to avoid killing beneficial insects & predators


Integrated Pest ManagementIntegrated Pest Management


The goal of integrated pest management is to keep each pest population just below the size at which it causes economic loss.

Fig. 21–12

Biological ControlBiological Control


Example: For normal insect growth, development, & reproduction to occur, certain juvenile hormones (JH) & molting hormones (MH) must be present at appropriate stages of the life cycle. If applied at the proper time, synthetic hormones disrupt the life cycles of insect pests & control their population.

Fig. 21–10

chapter 12 food, soil & pest management tutorial by sharon ashworth & paul rich ©...

Documents

increasing food production

world food supply

new types of food

inputs of water

large inputs of fertilizer

world population

increasing affluent

land increased yields