5.3: The Green Revolution

Learning Objective: Describe changes in agricultural practices

Essential Knowledge:

• The green revolution shifted to new agricultural strategies and practices to increase food production, with both positive and negative results. Some of these strategies and methods are mechanization, genetically modified organisms (GMOs), fertilization, irrigation, and the use of pesticides

• Mechanization of farming can increase profits and efficiency for farms. It can also increase reliance on fossil fuels

The green revolution

Shift in agriculture away from small, family-operated farms to large, Industrial-scale agriculture

• Increased the use of mechanization, GMOs, irrigation, fertilizers, and pesticides

• Benefit:

  • Greatly increases the efficiency of lands, short-term profitability, and food supply

  • Decreased world hunger and increased earth’s carrying capacity for humans

• Negatives: Consequences (soil erosion, biodiversity loss, ground & surface water contamination)

Mechanization

• Increased use of tractors for plowing and tilling fields, and combines for harvesting

• Benefits:

  • Increased yield + profits

• Negatives:

  • Increases reliance on fossil fuels (gasoline/diesel fuel)

    • Emits GHGs to atmosphere → Climate change

  • Heavy machinery also compacts the soil, decreasing H2O holding capacity

    • Makes topsoil more prone to erosion

High-yield variety (HYV) crops

• Hybrid, or genetically modified crops that produce a higher yield (amount of crop produced per unit of area)

  • Hybrid = cross-pollinating different species, or parent plants with ideal traits

• Benefits:

  • Increased yield and food stability in regions previously prone to famine (India, Pakistan, Mexico)

• GMOs = Crops with new genes “spliced” into their genome

GMOs

• Genetically modified crops have genes for drought tolerance, pest resistance, faster growth, and larger fruit/grain

• Benefits:

  • Increases profitability with fewer plants lost to drought, disease, or pests + larger plant size + yield/acre

• Negatives:

  • GMO crops are all genetically identical so genetic diversity is decreased and susceptibility to diseases or pests is increased

• Ex:

  • BT corn has been modified with a gene from soil bacteria (Bacillus thuringiensis) to produce a protein that kills many different corn pests

Synthetic Fertilizer

• Shift from organic fertilizers (like manure and compost) to synthetic fertilizers (man-made ammonium, nitrate, phosphate)

• Benefits:

  • Increases yield and profits with more key nutrients needed for plant growth (N, P, K) added to the soil

• Negatives:

  • Excess nitrate, and phosphate are washed off fields and into nearby waters where they cause eutrophication (algae blooms)

  • Require FFs for production, releasing CO2 (climate change)

Irrigation

• Drawing water from the ground or nearby surface waters and distributing it on fields to increase plant growth

• Benefits:

  • Make agriculture possible in many parts of the world that are naturally too dry (don’t receive enough rain)

• Negatives:

  • It can deplete groundwater sources, especially aquifers

  • Overwatering can drown roots (no O2 access) and cause soil salinization (increase salt level in soil)

Pesticides

• Increases in the use of synthetic pesticides - chemicals sprayed on crops that kill weeds, insects, rodents, and other pests that eat or damage crops

• Benefits:

  • Increases yield and profits with fewer plants lost to pests

• Negatives:

  • Can wash off crops in runoff and kill or harm non-target species in local soil or waters (bees especially)

  • Ex:

    • DDT thinned shells of bird eggs, especially eagles

    • Atrazine turns amphibians and fish intersex