ESC110 Chapter Seven Food and Agriculture

Chapter Seven Readings & ObjectivesRequired Readings

Cunningham & Cunningham, Chapter Seven

Food and Agriculture

After finishing this chapter, you should be able to:

describe world food supplies and some causes of chronic hunger in the midst of growing food surpluses;

explain some major human nutritional requirements, as well as the consequences of deficiencies in those nutrients;

differentiate between famine and chronic undernutrition and understand the relation between natural disasters and social or economic forces in triggering food shortages;

sketch the roles of living organisms, physical forces, and other factors in creating and maintaining fertile soil;

differentiate between the sources and effect of land degradation, including erosion,

nutrient depletion, waterlogging, and salinization;

analyze some of the promises and perils of genetic engineering; explain the need for water, energy, and nutrients for sustained crop production, as

well as some limits on our use of these resources;

recognize the potential for low-input, sustainable, regenerative agriculture.

Chapter Seven Key Terms

anemia - page 152 of text

chronically undernourished 150

contour plowing 166

cover crops 167

famines 151

food securitty 150

genetic engineering

Genetically Modified Organisms (GMOs) 164

green revolution 163

gully erosion 160

Kwashiorkor 153

Malnourishment 152

Marasmus 153

Mulch 167

obese 152

perennial species 167

reduced tillage systems 168

regenerative farming 166

rill erosion 160

salinization 161

sheet erosion 160

soil 156

soil horizons 157

strip-farming 166

subsoil 157

sustainable agriculture 166

terracing 167

topsoil 156

waterlogging 161

Chapter Seven Topics

• Nutrition and Food Supplies

• Major Food Sources

• Soil: Basis for Renewable Agriculture

• Ways We Use and Abuse Soil

• Other Agricultural Resources

• New Crops and Genetic Engineering

• Sustainable Agriculture

Part 1: Nutrition and Food Supplies

• World food supplies: 1950 versus 2000• Richer countries: the most common dietary

problem is over-nutrition (obesity)• Sub-Saharan Africa: food production has not

kept pace with rapid population growth• Asia: most rapid increase in crop production

and this accompanied rapid population growth

Chronic Hunger and Food Security - within families that don't get enough to eat, women and children have the poorest diets.

World Grain, Food Production

Countries at risk for inadequate nutrition

On the left is shown the number of chronically undernourished people in developing regions. The most hungry people live in East and South Asia. Persistent hunger is a major problem in Africa where the problem is getting worse.

Famines are characterized by large-scale food shortages, massive starvation, social disruption,

and economic chaos. Some causes are:

• Environmental conditions - drought, insects, natural disasters

• National politics - corruption, oppression

• Armed conflict• Economics - price

gouging, poverty, landlessness

Essential Nutrients

• Malnourishment - a nutritional imbalance caused by a lack of specific dietary components or an inability to utilize essential nutrients

• Starchy foods like corn and polished rice tend to be low in several essential nutrients.

• Protein deficiency diseases - kwashiorkor, marasmus (see next slide).

• Iron deficiency (anemia) - is the most common dietary deficiency in the world and is most severe in India.

• Iodine deficiency - causes goiter, hyperthyroidism

Protein Deficiency Diseases

• Kwashiorkor - "Displaced Child" - Occurs mainly in children whose diet lacks high-quality protein.

•Marasmus - "To Waste Away" - Caused by a diet low in both protein and calories.

Obesity - The most common dietary problem in wealthy countries is over-nutrition.

PART 2: MAJOR FOOD SOURCES

• Wheat, rice and maize) are responsible for the majority of the world's nutrients.

• Potatoes, barley, oats and rye are staples at high latitudes with cool, moist climates.

• Potatoes, barley, oats and rye are staples in cool, moist climates.

• Cassava, sweet potatoes, and other roots and tubers are staples in warm wet climates.

• Sorghum and millet are drought resistant and staples in dry regions of Africa.

• Fruits, vegetables and vegetable oils contain high levels of vitamins, minerals, dietary fiber and complex carbonhdrates.

Crops

Annual Production of Important Foods

Below - Rice plants (a type of grass or grain)

Eating a Balanced Diet as Determined byUSDA Food Pyramid

Meat, Milk, and Seafood

• Milk and meat are highly prized, but their distribution is inequitable. Developed countries make up 20% of world population, but consume 80% of meat and milk production. Less developed countries produce 60% of world's milk and meat.

• About 90% of the grain grown in North America is used to feed cattle, hogs, poultry, and other animals!

• Seafood is an important protein source in many countries. This food source is threatened by over-harvesting and habitat destruction.

Environmental Issues with Raising Beef• Every 16 kg of grain and soybeans fed to beef cattle in

feedlots produce 1 kg of edible beef.– If we ate grain directly, we would obtain twenty-one times more

calories and eight times more protein than we get eating the beef.

PART 3:SOIL - A VALUABLE RESOURCE

• Soil - a complex mixture of weathered minerals, partially decomposed organic matter and a host of living organisms

• We depend on soil for life, yet tend to take this living resource for granted.

• U.S. has > 20,000 different soil types that vary due to influences of parent material, time, topography, climate and organisms

• About 30-50% of the world's croplands are losing topsoil faster than it can be replaced

• Soil is a renewable resource, but building good soil is a slow process.

Soil Organisms

Without soil organisms, the earth would be covered with sterile mineral particles.

Soil Profile - soilsare stratified intohorizontal layerscalled soil horizons,and together they make up the soil profile

PART 4: WAYS WE USE & ABUSE SOIL

Much potential cropland suffers from constraints.

• Approximately 11% of the earth's land area is currently in agricultural production.– Up to four times as

much could potentially be converted to agricultural use.

• Much of this additional land suffers from constraints.

Land Resources

• Cropland per person averages only 0.7 acres worldwide. By 2025, this could decline to 0.42 acres.

• In developed countries, 95% of recent agricultural growth has come from improved crop varieties or increased fertilization, irrigation, etc.

• Land conversion involves ecological trade-offs • Many developing countries are reaching limit of

lands that can be exploited for agriculture without unacceptable social and environmental costs.

Areas of Concern for Soil Degradation

Worldwide Soil Degradation• Estimated nearly 3 million ha (7.5 million acres)

of cropland is ruined annually via erosion, 4 million ha transformed into deserts, and 8 million ha converted to non-agricultural uses.

Erosion: The Nature of the Problem

• Erosion is an important natural process, resulting in redistribution of the products of geologic weathering, and is part of both soil formation and soil loss.– Tends to begin subtly.

• Worldwide, erosion reduces crop production by equivalent of 1% of world cropland per year.

Mechanisms of Erosion

• Sheet Erosion - Thin, uniform layer of soil removed.

• Rill Erosion - Small rivulets of running water gather and cut small channels in the soil.

• Gully Erosion - Rills enlarge to form channels too large to be removed by normal tillage.

• Streambank Erosion - Washing away of soil from established stream banks.

Mechanisms of Erosion (continued)

• Wind can equal or exceed water as an erosive force, especially in a dry climate and on flat land.– Intensive farming practices:

• Row crops leave soil exposed• Weed free-fields• Removal of windbreaks• No crop-rotation or resting

periods• Continued monocultures

PART 5:OTHER AGRICULTURAL RESOURCES

• Water

• Fertilizer

• Energy

• Pesticides

Agriculture is the biggest global consumer of water, but there are many ways we can reduce water use (above - downward facing sprinklers deliver water more efficiently than upward-facing ones).

Fertilizer

• Lack of nitrogen, potassium, and phosphorus often limits plant growth.– Adding nutrients via fertilizer usually stimulates growth

and increases crop yields.• 1950 - Average of 20 kg/ha fertilizer used.

• 2000 - Average of 90 kg/ha fertilizer used.

– Manure and nitrogen-fixing bacteria are alternative methods of replenishing soil nutrients.

Total Energy Use in U.S. Agriculture

•Farming in industrialized countries is highly energy-intensive.

–Altogether, US food system consumes 16% of total energy use.

Pest Control

• Biological pests reduce crop yields and spoil as much as half the crops harvested annually.– Estimated up to half current crop yields might be lost in

the absence of pesticides.

• Crops grown without synthetic fertilizers or pesticides tend to have lower yield, but have lower operating costs and less ecological damage.

Up to 90% of all pesticides never reach target organisms.

PART 6: NEW CROPS & GENETIC ENGINEERING

• At least 3,000 species of plants have been used for food at some point in time, but most world food comes from 16 crops..

– Many new or unconventional varieties might be valuable food supplies.

– Winged-bean - can eat all parts and grows in new, warm habitat

– Triscale - drought resistant and grows in light, sandy, infertile soil

• So far, the major improvements in farm production have come from technological advances and modification of a few well-known species.

• The green revolution refers to the global spread of new, high-yield varieties of plants. These varieties are "High responders" to optimum levels of fertilizer, water, pesticides, light, etc.

Green Revolution "Miracle Crop" Yield

Genetic Engineering

• Genetic engineering is the splicing a gene from one organism into the chromosome of another.

• These Transgenic organisms are called Genetically Modified Organisms (GMOs) produced

• These new genes result in plants with pest resistance, built in weed control and wider tolerances

• Opponents fear traits could spread to wild varieties, and increased expense would largely hurt smaller farmers.

Transgenic Crop Field Releases

PART 7: SUSTAINABLE AGRICULTURE

• Sustainable agriculture (regenerative farming) - goal is to produce food and fiber on a sustainable basis and to repair damage caused by destructive practices. Soil is essential to sustainable agriculture.

• Soil conservation - land management, ground cover, climate, soil type and tillage system are important elements in soil conservation.

Ways to Manage Topography

• Contour - Plowing and planting across (with the contour) slope to slow flow of water (left).

• Strip-farming - Planting different crops in alternating strips along land contours (left).

• Terracing - Shaping land to create level shelves of earth again with the slope to hold water and soil (see next slide).

• Planting perennial (plants that live >2 years) species

Flooded terraces for growing rice in China

Providing Ground Cover

Providing Ground Cover and Reducing Tillage

Methods Used to Reduce Bare Ground Erosion

• Providing Ground Cover• Leave crop residue after harvest.• Plant cover crops after harvest.• Add protective ground cover such as manure, wood

chips, straw, leaves, etc. (mulch).

• Reduced Tillage– Minimum Till - Chisel plow or ridge-tilling– Conserv-Till - Coulter (Disc)– No-Till - Drilling

• Often farmers using conservation tillage must depend relatively heavily on pesticides.

Cocoa pods (left) are growing directly on branches of a shade-tolerant tree native to warm, moist lowland forests of the tropics. In contrast, coffee is native to cool, mountain forests of the tropics.

Organic and Locally Grown Foods

SUMMARY• Today the world's food is increasing faster than its population, but still

one-fifth of the people are hungry and malnourished.• Stunted growth, mental retardation, immunological deficiencies and

developmental disorders due to chronic malnourishment affects 800 million people and 15 million (mostly in Africa) face starvation.

• Lack of adequate calories, proteins, vitamins and minerals cause diseases such as marasmus, kwashiorkor, anemia, goiter and death and blindness (vitamin A deficiency).

• Rice, wheat and maize provide most of world with calories, and modern techniques can increase productivity but such techniques create environmental and social problems.

• Variations in soil types (and productivity) are a function of climate, topography, history, parent material and organisms.

• Soil is necessary for producing food, yet we lose it to erosion and other forms of degradation.

• New, alternative farming methods can reduce erosion, avoid dangerous chemicals and improve yields with fair and sustainable agriculture.