Chapter 11: Food & Agriculture

In this chapter we will cover the following topics:

I. Nutrition & Food Supplies.

II. Major Food Sources

III. Soil: A Renewable Source

IV. Ways we Use and Abuse Soil

V. Other Agricultural Resources

VI. New Crops and Genetic Engineering

VII. Sustainable Agriculture

Nutrition and Food Supplies

• Food production per capita has increased since 1950 • Most gains in Indonesia • Wealthy nations have problem of too much caloric intake • Success of food production is not distributed equall

Chronic hunger and food security

• 20% of DALY suffered/year is related to chronic nutritional deficits

• Poverty is greatest threat to food security • Hunger affects greatest numbers in east, southeast, and south Asia

Other Essential Nutrients

• Mal-nourishment: nutritional imbalance • Kwashiorkor disease: bloated belly syndrome in children from

lack of high quality protein • Marasmus disease: low calorie and protein diet create shriveled,

thin condition in children • Vitamin A deficiency in children: 250,000 / year go blind in

developing countries • Iron deficiency: most prevalent mineral deficiency in the world,

3.6 billion • Iodine deficiency: 26 million children / year

Eating a Balanced Diet

• Current emphasis on grains, fruits, and vegetables (U.S.)

Famines

• Characterized by mass migrations • Environmental factors usually immediate trigger, e.g. floods in

Bangladesh (1974) • Armed conflict and political oppression at root of famine

(Amartya Sen)

Major Food Sources

Major Crops

• Wheat, rice, and maize: important to 5 billion people in developing countries

• Potatoes, barley, oats, and rye: northern Europe, north Asia

• Roots and tubers: Amazonia, Africa, Melanesia, and South Pacific

• Fruits and vegetables

Table 11.1 -- Some important food resources

Crop 1998 Yield (million metric tons) Wheat 586 Rice 384 Maize (corn) 597 Potatoes 281 Barley and oats 170 Soybeans 155 Cassava and sweet potato 286 Sugar (cane and beet) 119 Sorghum and millet 84 Vegetable oils 91 Vegetables and fruits 884 Meat and milk 432 Fish and seafood 94 Source: World Watch Institute 1999

Meat, Milk, and Seafood

• These high protein sources are not distributed equally throughout the world

• 20 percent of worlds population (developed countries) consume 80% of the seafood

• 13 of 17 major fisheries are depleted past commercial viability

• Fishing technology increased efficiency, but is responsible for catching non-target species (1 in 4 animals is non-target)

• Subsidies maintain large, viable fishing industry

• Fish farming offers alternatives, but may have environmental impacts

Soil: A Renewable Resource

Soil Composition

• 50% mineral (weathered bedrock) • Humus: organic matter (decomposed plant and animal matter) • Clay, sand, humus help define the micro-structure of soil and its properties

Table 11.2 -- Soil particle sizes Classification Size

Gravel 2 to 64 mmSand 0.05 to 2 mmSilt 0.002 to 0.05 mmClay Less than 0.002

Soil Organisms

• Algae, blue-green algae on soil surface • Bacteria and fungus in top layer • Worms, mites, and insects in top layers • Burrowing animals move nutrients from various layers • Plant roots move minerals from lower layers

Soil Profiles

• Soil horizons, cross-sectional view of soil • "A" horizon = top soil • "B" horizons = sub-surface • "C" horizons = parent material, rock fragments and very little organic material; most of this material is not of bedrock origin in U.S.

Soil Types

• Richest soils: mollisols (grasslands), alfisols (deciduous forests)

Ways We Use and Abuse Land

Land Resources

• World average of cropland per person is expected drop to 0.17 ha (0.42 ac) by 2025

• Developed countries are putting less land under cultivation as seed varieties are developed and technology increases

• Developing countries are sacrificing forested land for agriculture.

• Largest increases in cropland are in South America and Oceania

• Some arable land is more stable and useful in an uncultivated state

• Argentina has land (larger than Texas) that is currently unused, but viable as cropland

Table 11.3 -- Cropland by region and per capita ----------------------------------------------------------------------------------------Region Population Cropland Cropland/capita (millions) (millions of hectares) ---------------------------------------------------------------------------------------- Africa 778 190 0.24Europe 729 316 0.43North America 304 233 0.77Central America 131 41 0.31South America 332 115 0.35Asia 3,589 622 0.17Oceania 29 52 1.79World 5,892 1,569 0.27 ---------------------------------------------------------------------------------------- *Oceania includes Australia, New Zealand, and many small-island nations Source: World Resources 1998-1999, World Resources Institute.

Land Degradation

• 1.9 billion ha of agricultural land has been degraded in last 50 years

• 3 million ha (7.4 million ac) are degraded by erosion every year

• Erosion: degrades land as well as waterways (sediment loading), powerplants (water intakes), coral reefs, and wetlands

Mechanisms of Erosion

• Rill and gully erosion occur by water run-off

• Rill erosion can account for 20 metric tons of soil loss per ha

• Streambank erosion occurs at site streams stripped of trees and brush

• Wind equals or exceeds water erosion. Wind carries soil from continent to continent

Erosion Hotspots

• China: Huang (Yellow) River carries up to 20 times the sediment load of Mississippi River at 1/5 the drainage area • Haiti: considered to have no topsoil left (Haiti was once covered by tropical forest)

Other Agricultural Resources

Water

• 73% of all water withdrawn from lakes, rivers, and groundwater is for agricultural

• Unlined / uncovered canals lose up to 80% of their water to evaporation

• Waterlogging: overuse saturates soil and suffocates plant roots

• Salinization: evaporated water leaves salts on soil surface, which creates toxic soil conditions

Fertilizer

• Fertilizer use: 20 kg per ha (1950), 91 kg per ha (1990) worldwide • Appropriate use of fertilizers is important (Europeans use twice the levels of U.S. without substantial gains) • Phosphates and nitrates are major source of aquatic pollution (run-off) • Nitrogen fixing bacteria (in leguminous plants) help recycle nitrates to useable form of nitrogen in agricultural soils • Fertilizers help maximize crop production (Africa has potential to increase current use levels; currently at 19 kg / ha)

Energy• Farming is energy intensive (mechanized machinery is increasing in use) • The U.S. food system consumes 16% of all energy used • Present energy system is unsustainable

New Crops and Genetic Engineering

• New crops are being developed to grow in traditionally unarable land (winged beans, triticale, tepary beans, amaranth, and Sonoran panicgrass)

• Seed collections important in maintaining seed stocks of native crops (Gary Nabhan)

Green Revolution

• Revolution refers to development of high yielding crop varieties, which have helped, keep pace with increasing populations (nobel prize: Norman Borlaug)

• High yield plant breeds are very responsive to increased fertilizer applications, which leaves some farmers uncompetitive due to increased cost of farming

Genetic Engineering

• Refers to manipulation of plant characteristics by changing the genes that control them • Transgenic plants that contain non-native genes are used to increase production, tolerance, and shelf life of the final product • Examples: frost resistant strawberry (interaction with transgenic bacteria), long shelf-life tomato, anti-body producing tobacco, various corn, soybean, and cotton crops • 20 million ha planted with transgenic crops in U.S., 50% of all Canadian canola crops and Argentinean soybeans

Pest Resistance

• High prevalence of (bt) corn: transgenic crop contains bacterium genes for natural pesticide production by the crop plant • High probability for "creating" insecticide resistant insects if continuous exposure to insecticide occurs • The (BT) toxin may also be toxic to beetles and butterflies

Weed Control

• High use of herbicide resistant crops, which allow extermination of weeds with seed producer's own brand of herbicide (round-up ready crops from Monsanto resist Round-up herbicide) • May produce super weeds if resistant genes are transferred to closely related weed relatives (has occurred with transgenic canola in Canada). The chances of this happening is very minimal.

Public Opposition

• Opposition to somatotropin (growth hormone) treatment of dairy cows • Europe grocery stores refuse to stock genetically modified corn, wheat, potatoes, and soybeans • India bans testing of transgenic crops

Sustainable AgricultureSustainable agriculture includes the repair of damage by destructive practices

Soil Conservation• Soil is considered a renewable resource • Examples: 1000-year-old rice paddies in Asia

Managing Topography • Contour plowing, strip farming, and terracing are useful for reducing erosion, retaining water, and making use of hillsides

Providing Ground Cover • Crop residue help reduce water and wind erosion • Cover crops: alfalfa, rye, and clover • Interplanting different crops crowds out weeds • Mulch (various sources); Israel uses plastic sheeting (millions of square meters) as mulch to reduce erosion and weed growth

Reduced Tillage • Minimum tillage: disc or chisel plow with reduced turnings of soil • Conserv-till: coulter plow; opens soil just for seed insertion • No-till: seeds drilled directly through mulch

Low-Input Sustainable Agriculture

• Involves more crop rotation • Less pesticides or none • Less fertilizer, water, heavy machinery, and fossil fuels • Absolute production (and monetary intake) is less, but net take can be higher because costs are lower • Smaller, family farms are much closer to sustainability than the large factory farms

Summary

• There is enough food for everyone • 15-20 million children die each year from malnourishment • Good health requires proteins, vitamins, and minerals: many people suffer from inadequate supplies of these in their diet(disease conditions) • Rice, wheat, and corn are world's major crops • Technology can keep increasing food production in areas with growing populations • Fertile, tillable soil is essential. Soil is delicate and complex which presents a challenge in conserving arable land • Erosion by wind and water remove soil from sites of agriculture. About 50% of the topsoil has been lost from U.S. since settlement by Europe • Low-input, organic farming may be more sustainable than current practices