Ch 14: Agricultural Methods and Pest Management

Outline

• 14.1 The Development of Agriculture• 14.2 Fertilizer and Agriculture• 14.3 Agricultural Chemical Use• 14.4 Problems with Pesticide Use• 14.5 Why Are Pesticides So Widely Used?• 14.6 Alternatives to Conventional Agriculture

14.1 The Development of Agriculture

• Development of agriculture involved manipulating the natural environment to produce food desired by humans.

• This allowed an increase in the size of the human population.

• Three different types of farming:– Shifting agriculture– Labor-intensive agriculture– Mechanized monoculture agriculture

14.1 The Development of Agriculture

• Shifting agriculture- cutting down and burning the trees and other vegetation in a small area of the forest.– Burning releases nutrients bound up in biomass.– The cleared soil is useful for 2-3 years.– Forest eventually recolonizes the area.– Particularly useful on thin tropical soils.– Not suitable for large, densely populated areas. – Requires a long recovery time between cycles.

14.1 The Development of Agriculture

• Shifting agriculture often employs polyculture – The planting of a mixture of plants.

• Labor-intensive agriculture is practiced in much of the developing world.– Three situations favor this type of agriculture:• The growing site does not allow mechanization.• The crop does not allow mechanization.• The economic condition does not allow purchase of

mechanized equipment.

14.1 The Development of Agriculture

• The primary reason for the use of labor-intensive agriculture is economic. – Many densely populated countries have numerous

small farms that can be effectively managed with human labor.

14.1 The Development of Agriculture

• Mechanized monoculture agriculture is typical of industrialized countries.– Fossil fuel replaces human muscle power.– This method requires large amounts of energy and

flat land.– Monocultures promote more efficient planting,

cultivating, and harvesting.– Farmers often rely on hybrids to provide uniform

monocultures.

14.1 The Development of Agriculture

• Labor reduction in the United States: – 1913: 135 hours of labor required to produce 2,500 kg of

corn.– 1980: 15 hours of labor required to produce 2,500 kg of

corn.• It takes 5 metric tons of fossil fuel to produce 1 metric

ton of fertilizer.– The developed world is dependent on oil to produce energy

to manufacture pesticides and fertilizer and to run machines.– The price of oil has wide ramifications on the world’s ability

to feed itself.

14.1 The Development of Agriculture

• Problems with mechanized monoculture agriculture include:– Large tracts of bare land increases soil erosion.– The planting of genetically identical seeds results in

the loss of genetic diversity.– Little genetic differentiation often leads to increased

pesticide use.– No crop rotation depletes soil nutrients, increasing

fertilizer use.– Fossil fuel energy use has replaced human muscle

power.

14.1 The Development of Agriculture

• The Green Revolution has greatly increased worldwide food production.– Introduction of new plant varieties and farming

methods has increased food production per hectare.– Drawbacks:• Modern varieties of plants require fertilizer and pesticides

that traditional varieties did not need. • Requires larger amounts of water and irrigation.

14.1 The Development of Agriculture

• Increased production has not solved the world’s food problem because population continues to increase.

• Global answers are needed for difficult problems.– Governments protect farmers with subsidies and trade

barriers. Farming is hindered in poorer nations.– High fuel costs increase food costs.– High energy prices divert crops to be used as fuel crops.– Higher demand for meat uses crops that could have

been consumed directly by humans.

14.1 The Development of Agriculture

Increased yields resulting from modern technology and the total amount of land available for cultivation.