Land Use Part I: Agriculture

Food and Nutrition• Foods humans eat are composed of

several major types of biological molecules necessary to maintain health :

• Carbohydrates– Sugars and starches metabolized

by cellular respiration to produce energy

• Proteins– Large, complex molecules

composed of amino acids that perform critical roles in body

• Lipids– Include fats and oils and are

metabolized by cellular respiration to produce energy

• Vitamins and Minerals

Agricultural Land Use• Agriculture now covers more of Earth’s surface

than forests.– 38% of planet’s land surface is used for agriculture• 26% pasture/rangeland• 12% cropland

Using Land For Agriculture

• Humans need:

– Most women need ~2,200 kilocalories / day

– Men, ~ 2,900 kilocalories / day

• Biologists estimate that there are roughly 30,000 plant species with parts that humans can eat

• Majority of our food supply (90%) is derived from only 15 plant and 8 animal species

• Three grains, wheat, rice, and corn, provide almost half of the calories consumed by people

– These three species are all annual plants

• 2 out of 3 people on Earth survive primarily on grains

• World food supplies have more than kept up with human population growth over the past two centuries.

– During the past 40 years, population growth has averaged 1.7% per year, while food production increased an average 2.2%.

Chronic Hunger and Malnutrition• Chronic undernutrition

– Occurs when people cannot grow or buy enough food to adequately nourish themselves

– Consequences:• Mental retardation, stunted growth, increased susceptibility to infectious diseases

• Malnutrition – Occurs from low-protein diets that are common in countries where

subsistence farming is the most common method of food production• Nearly 6 million children die prematurely each year from undernutrition,

malnutrition, and their effects.

Hunger Around the World

Principle Types of Agriculture• There are two Principle Types of

Agriculture1. Traditional Agriculture – Low Input Polyculture• Human and animal labor used

to produce only enough food for farming family’s survival

2. Industrialized agricultureHigh Input Monocultures– Produce huge output of

single crops (monocultures) or livestock (which are often fed monoculture products)

Traditional Agriculture: Low Input Polyculture• Many farmers in developing countries use low-input agriculture to

grow a variety of crops on each plot of land (interplanting) through:

– Polyvarietal cultivation• Planting several genetic varieties.

– Intercropping/Polyculture• Two or more different crops grown at the same time in a plot.

Polyculture Agriculture• Advantages of polyculture:

– Crops mature and ready to harvest at different times

– Provides food throughout the year

– Soil constantly covered, preventing erosion

– Less need for fertilizer and water because roots are at different depths, using more of soil and increasing efficiency

– Creates habitats for natural predators of pest species, reducing need for pesticides and herbicides

Industrial Food Production: High Input Monocultures

• Requires large amounts of energy, water, fertilizers, antibiotics, and pesticides; three of which come from fossil fuels

• Produce huge output of single crops (monocultures) or livestock (which are often fed monoculture products)

• Accounts for roughly 25% of the world’s cropland• Mostly in developed countries, but it is spreading into

developing nations

Industrialized Food Production in the United States

• The U.S. uses industrialized agriculture to produce about 17% of the world’s grain.– Relies on cheap energy to run machinery, process food, produce commercial

fertilizer and pesticides.• About 10 units of nonrenewable fossil fuel energy are needed to put

1 unit of food energy on the table.• 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.

Sources of Protein -- Livestock• One of the principal uses of animals in agriculture is to

transform plant material into high-quality protein • In traditional agriculture, livestock graze land, taking nutrients

in and then they defecate and return some of the nutrients to the same field

• In industrial agriculture, livestock are fed grains (corn particularly, which they are not “designed” to do) and not necessarily in a field, so the manure does not fertilize a field

• Per capita meat consumption has increased 29% between 1950 and 1996

• 1/5th of the world’s population consume roughly half of the world’s grain production through livestock

Sources of Protein -- Seafood• Seafood is an important protein

source.• Since 1989, 13 of the 17 major

fisheries in the world have declined or become commercially unsustainable.

• If current practices continue, the world’s fisheries will be exhausted by 2048.

• Aquaculture (growing aquatic species in pens) is providing an increasing share of the world’s seafood.

Green Revolution• In 1960, 60% of the population of developing countries was considered

chronically undernourished.– Fallen to less than 14% today

• Due to major improvements in farm production which came from technological advances and modification of a few well-known species.– Corn yields jumped from 25 bushels per acre to 130 per acre in last

century.• Most of gain accomplished through conventional plant breeding

• Green Revolution started by Norm Borlaug. – Promoted the use of dwarf, high yielding wheat and rice grown

around the world.– Do require fertilizers and protection from pests. – Borlaug won Nobel Peace Prize.