The Green Revolution
The Green Revolution transformed the agricultural system in the 20th Century. It shifted farm methods from a system of small farms relying mainly on human labor and with relatively low
fossil fuel inputs to a system of large industrial operations with fewer people
and much more machinery. It increased food production dramatically through new management techniques, mechanization, the introduction of fertilizers, irrigation, and improved crop varieties. Ever since then, farmers have been able to feed many more people.
Components of the Green Revolution
Mechanization
- Machines make farm work easier and faster
- Economically advantageous when fossil fuels are abundant, fuel prices are relatively low, and labor prices are relatively high
- Doesn't necessarily make the farm work better than humans or animals
- Large farms producing staple crops such as beans or corn have generally been more profitable than small farms
- Economies of scale- the average costs of production fall as the output increases
- Single-crop farms are generally more efficient than farms that grow many crops
- Planting and harvesting only a single type of crop reduces equipment costs
Irrigation
- Allows productive land to become extremely productive land
- Can transform deserted areas into productive land
- Only 16% of the world's agricultural land is irrigated, however, that same land produces 40% of the world's food
- Benefit = more efficient use of water where water is scarce
- Consequences = depletes groundwater, draws down aquifers, contributes to soil degradation
- Waterlogging- occurs when soil remains under water for prolonged periods, impairing root growth because roots cannot get oxygen
- Salinization- occurs when the small amounts of salts in irrigation water become highly concentrated on the soil surface through evaporation
Fertilizers
-Plants can easily absorb them
-Consequences = uses fossil fuel energy, can be carried by runoff into adjacent waterways and aquifers causing algal bloom, don't add
any organic matter to the soil
- Contain essential nutrients for plants - primarily nitrogen, phosphorus, and potassium
- Foster plant growth where one or more of the above nutrients is lacking
- Organic fertilizers- fertilizers composed of organic matter from plants and animals (typically made up of animal manure that has been allowed to decompose)
- Inorganic/Synthetic fertilizers- fertilizers that are produced commercially and are designed for easy application
-Plants can easily absorb them
-Consequences = uses fossil fuel energy, can be carried by runoff into adjacent waterways and aquifers causing algal bloom, don't add
any organic matter to the soil
Monocropping
- The large plantings of a single species or variety
- Dominant agricultural practice in the U.S. (wheat and cotton)
- Allows large expanses of land to be planted, and then harvested, all at the same time
- Use of machinery is efficient and easy
- Consequences = soil erosion, makes crops more vulnerable to attack by pests, removes habitat for predators that might otherwise control the pest population
Pesticides
-Herbicides- target plants species that compete with crops
-Broad-spectrum pesticides- kill many different types of pests
-Selective pesticides- focus on a narrower range of organism
-Persistent- pesticides that remain in the environment for a long time (ex. DDT)
-Nonpersistent- pesticides that break down relatively rapidly, usually in weeks to months
-Can eventually lead to very high pesticide concentrations at high trophic levels
- Substances, either natural or synthetic, that kill or control organisms that people consider pests
- U.S. accounts for about 13 of worldwide pesticide use
- Application is rapid
- Allows greater crop yields on less land, reducing the area disturbed by agriculture
- Types:
-Herbicides- target plants species that compete with crops
-Broad-spectrum pesticides- kill many different types of pests
-Selective pesticides- focus on a narrower range of organism
-Persistent- pesticides that remain in the environment for a long time (ex. DDT)
-Nonpersistent- pesticides that break down relatively rapidly, usually in weeks to months
- Consequences = can injure or kill organisms (some beneficial) other than their intended targets, bioaccumulation, pest populations may evolve resistance to pesticides over time
- Bioaccumulation- an increased concentration of a chemical within the fatty tissues of an organism over time
-Can eventually lead to very high pesticide concentrations at high trophic levels
- Pesticide resistant- a pest that survives a pesticide application
- Pesticide treadmill- the cycle of pesticide development, followed by pest resistance, followed by new pesticide development