APES - Agriculture and Pesticides Notes

Agriculture and Pesticides

Agriculture Challenges & Drawbacks

  • Feeding a growing population requires efficient farming and livestock techniques.
  • Market and distribution problems lead to hunger.
  • Environmental damage is a drawback.
  • More people = More food, land, water, and fossil fuels.

Types of Agriculture

  • Traditional Agriculture: Growing crops and raising livestock.
    • Traditional Subsistence: Human labor and draft animals on a family farm.
    • Traditional Intensive: Increased labor inputs to feed family and sell.
  • Industrial (Conventional) Agriculture: Uses large amounts of fossil fuel energy, water, commercial fertilizer, and pesticides for monoculture.
    • Practiced on ¼ of croplands, mostly in developed countries
    • Produces 4/5 of the world’s food

Environmental Impacts of Agriculture

  • Environmental damage includes:
    • Tilling
    • Slash and burn practices
    • Fertilizer use

The Green Revolution (1950-1960)

  • Significant increase in food production via technological advances.
    • Inorganic fertilizers
    • Irrigation
    • Pesticides
    • Plant and animal breeding.
  • Led to global food export/import markets.
  • Environmental impacts:
    • Pollution (soil, air, water)
    • Decreased freshwater.
    • Reduced soil quality and increased erosion.
    • Desertification and salinization.
    • Monoculture pros
      • efficient planting/harvesting
    • cons
      • disease risk, fewer niches, decreased biodiversity.

Biodiversity Loss

  • Loss and degradation of grasslands, forests, and wetlands.
  • Erosion and loss of fertility.
  • Water waste and aquifer depletion.
  • Air pollution (greenhouse gases from fossil fuels and fertilizers).
  • Human health impacts from nitrates, pesticide residues, and bacterial contamination.

Genetic Engineering and Crop Production

  • Shift from wind/insect pollination to “Gene Revolution” with GMOs.
  • GMOs involve transferring genes between species for stronger, drought-tolerant, and insect-resistant plants.

Gene Revolution: Pros & Cons

  • Pros:
    • Feed more people with less energy.
    • Efficient farming.
    • Longer shelf life.
    • Thrive in harsh environments.
    • Disease resistant.
    • Reduced need for fertilizer and water.
  • Cons:
    • Unknown long-term effects on humans.
    • Super-weeds and insects.
    • New food allergens.
    • Cross-breeding concerns.
    • Ethical concerns (“Playing God”).
    • Patent on life.
    • GMO bans in some countries.

Crop Diversity

  • Biodiversity loss due to reliance on a small number of crop types and monocultures.
  • Seed banks preserve genetic diversity.

Irrigation

  • Good: 20% of cropland is irrigated, producing 40% of world’s food.
  • Bad: Leads to salinization (salt buildup) in soils.

Salinization

  • Stunts crop growth, lowers yields, and eventually kills plants.
  • Problem areas: China, India, Pakistan, Western US.
  • Solutions:
    • Prevention: reduce irrigation, drip irrigation, salt-tolerant plants.
    • Cleanup: flush soil (water intensive), stop growing crops, install drainage systems.

Waterlogging

  • Repeated irrigation can reduce crop yields by causing salt buildup in the soil and water logging of crop plants.

Sustainable Agriculture

  • Reduce impact through.
    • No-till farming (minimal soil disturbance)
    • Crop rotation
    • Intercropping
    • Shelterbelts
    • Contour farming and terracing.
  • Targeted use of resources like drip irrigation.
  • Organic Farming
    • No chemicals, antibiotics, or GMOs are used

Controlling Pests

  • Pests compete for food, invade areas, destroy property, and spread diseases.
  • Biggest pests: weeds, insects, fungi.
  • Natural enemies: spiders, wasps, parasites control pests.

Chemical Pest Control - Pesticides

  • Chemicals that kill or control pest populations.
  • First pesticides were natural plant defenses.
  • Second-generation pesticides produced in labs (e.g., DDT).

Efficiency When Compared to Alternatives

  • Pesticides control pests quickly and at a reasonable cost.
  • They have a long shelf life.
  • Easily shipped and applied.
  • Are safe when handled properly.

Types of Pesticides

  • Herbicides (plants)
  • Insecticides (insects)
  • Rodenticides (rodents)
  • Fungicides (fungi)
  • Nematicides (nematodes)
  • Algaecides (algae)
  • Bactericides (bacteria)
  • Piscicides (fish)

Persistence

  • Hard vs. Soft
    • Hard or POPs
      • Stay toxic for a long time (synthetic)
      • Stay in the food chain and accumulate in tissues
      • Example – DDT and PCBs
    • Soft
      • Short-term toxicity
      • Don’t harm man or the environment
      • Examples – soaps, oils, baking soda, dish liquid

Advantages vs. Disadvantages of Pesticides

  • Advantages:
    • Save lives by preventing insect-transmitted diseases.
    • Increase food supplies and profits for farmers.
    • Work fast and are relatively safe when used properly.
  • Disadvantages:
    • Accelerate genetic resistance (pesticide treadmill).
    • Kill natural predators and parasites.
    • Pollute the environment.
    • Harm wildlife and threaten human health.

Superbugs

  • Attack a variety of plants.
  • Be highly prolific.
  • Short generation time.
  • Genetically resistance to many pesticides.
  • Have few natural predators

Pesticide Poisoning

  • Short Term
    • Nausea, vomiting, headaches
    • Exposure to high levels – Harm organs and Death
  • Long-term exposure to lower levels can cause cancer and nervous system damage.
  • Children are at higher risk.

Reducing Exposure to Pesticides

  • Grow organic food.
  • Buy organic food.
  • Wash produce.
  • Eat less meat.

Label Requirements

  • the brand name
  • the ingredient statement
  • the percentage or amount of active ingredient(s) by weight
  • the net contents of the container
  • the name and address of the manufacturer
  • Signal words and symbols
  • Precautionary statement
  • Statement of practical treatment
  • Environmental hazard statement
  • Classification statement
  • Directions for use
  • Re-entry statement
  • Harvesting and/or grazing restrictions
  • Storage and disposal statement.

How Pesticides Work

  • LD-50 (Median Lethal Dose):
    • Amount of pesticide to kill ½ of target organisms in one dose.
  • Dose Response Curve:
    • Describes the effect on an organism or a mortality rate in a population based on the dose of a particular toxin or drug.
  • Other Methods
    • Interfere with nervous system
    • Inhibit photosynthesis and chlorophyll production

Chemical Pest Control – Case Study: DDT

  • Used to control agricultural pests and insect disease vectors.
  • Rachel Carson’s Silent Spring documented DDT's negative impacts.

Silent Spring

  • Carson researched effects of pesticide use in the 1950’s
  • Found that the pesticide bioaccumulated in the tissues of bird species.

Bioaccumulation

  • Weakened bird eggs.
  • Bald Eagle and other birds of prey neared extinction.
  • Found in tissues of top of the food chain.
  • Birth defects
  • Death

Non-chemical Pest Control

  • Integrated Pest Management (IPM):
    • Flexible application methods to kill pests
    • Hormones/Pheromones
    • Mechanical vacuuming
    • Hybrid plants
    • Planting time
    • Bring in enemies
    • Genetic resistance
  • Sterilized Male Insects
    • Males are sterilized rather than females because the male insects mate several times, whereas the females only mate once.

Chemical Pest Control

  • Relevant Laws
    • 3 agencies are responsible for regulating pesticides on food crops
    • EPA
      • Controls the sale and use of pesticides – FIFRA
      • Set acceptable pesticides limits in foods sold in the US – FFDCA
      • Delaney Clause – if a food additive could be shown to cause cancer in man or animal it could no longer be used
    • FDA and USDA
      • Enforces guidelines set by EPA and had authority to destroy any crop that does not meet EPA standards.