5.3 - The Green Revolution

Learning Objectives

I. Introduction and Context

• Goal: A global effort meant to help prevent the widespread starvation that was common before these agricultural improvements.

• Key Players: The movement centered on American agronomist Norman Borlaug, who won the Nobel Prize in 1970. Borlaug is credited with saving over 1 billion lives with his high-yield wheat varieties.

• Widespread Adoption: The high-yield crops greatly improved food supplies and economies in nations including Mexico, Pakistan, and India.
• Example: After Indian farmers adopted Borlaug's high-yield wheat, India's wheat harvest rose from about 12.3 million tons in 1965 to about 20.1 million tons in 1970, an increase of about 63% in five years.

• Shift in Farming: The revolution was a shift away from small family farming toward larger-scale industrial farming.

II. Advantages of the Green Revolution

III. Disadvantages and Environmental Consequences

• Practice: Using machines like tractors, tillers, and combines to rapidly harvest crops like wheat. This increased farm profits and yields.

• Fossil Fuel Reliance: Machines run on fossil fuels, mostly gasoline or diesel, producing $\text{CO}_2$ and other greenhouse gases that accelerate global climate change.

• Soil Degradation: Machines disturb, chop up, and mix the soil, which increases soil erosion. Over time they also compact the soil, which reduces its ability to hold water, dries it out, and makes it even more prone to erosion.

• HYV / Hybridization: Historically, HYVs were produced through hybridization, crossing parent plants with ideal traits like high productivity.

• Genetic Modification (GMOs): Modern techniques involve directly inserting a new gene into a plant’s genome, which lets crops be drought, disease, or pest resistant. That increases yield and profits. For example, BT corn is engineered to produce its own pesticide, reducing the need for chemical spraying.

• Loss of Diversity: High-yield and GM crops are bred to be uniform, and farmers across huge regions plant the same few varieties. That leaves the crop with very little genetic diversity, so a new disease or pest that can attack one plant can attack nearly all of them, risking total crop failure (see 5.6).

• Practice: Shifted from organic fertilizers like manure and plant matter to man-made synthetic chemicals containing nitrogen, phosphate, and potassium.

• Eutrophication: Farmers often use these cheap fertilizers in abundance. When it rains, the excess washes off the fields and into nearby bodies of water, causing eutrophication.

• Eutrophication causes huge algal blooms that block sunlight. When the algae die, bacteria decompose them, using up oxygen and leading to fish die-offs.

• Climate Change: Synthetic fertilizers are produced using fossil fuels, which increases greenhouse gas emissions and accelerates climate change.

• Practice: Allowed farmers to draw water from aquifers or surface waters and distribute it over crops, making agriculture possible in a lot of dry regions.

• Depletion: Aquifers recharge slowly and can be depleted if overused or drawn from faster than rainfall can replenish them.

• Soil Damage: Overwatering can cause waterlogged soil, which keeps roots from getting enough oxygen and kills the plant. It can also cause soil salinization, where salt left behind after water evaporates builds up to levels too high for plant growth.

• Practice: Using chemicals to kill agricultural pests, insects or weeds, to increase profitability and yields.

• Non-Target Species Harm: Excess pesticides can wash off or leach into surface waters, killing species they were never meant to target. This is especially a problem for bees, which pollinate many crops.

• Severe Impacts: The insecticide DDT caused thinning of eagle eggshells, which killed their hatchlings. Atrazine, a commonly used pesticide, can wash into waterways and cause intersex fish and amphibians that are sterile and can’t reproduce.

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