Agriculture Study Guide

Soil

• Watersheds:

  • Highest points/divide of a river

  • Tributaries: Smaller rivers that lead to a larger river

  • Source Zone: Snowpack/rain forms the river

  • Transition Zone: Clear, cold, fully oxygenated water

  • Floodplain: Spreads out, more sedimentation, less oxygen, warmer water

  • Rainwater movement: Runoff vs percolation into groundwater

  • Human impacts: Logging (sediment), agriculture (pesticides, fertilizers), industrial pollution, urban waste, dams (block sediment flow)

  • Factors affecting water quality: Area, length, slope, soil type, vegetation, pollutants

• Topography: How land shape influences water flow and soil composition

• Composition and Properties:

  • Important nutrients: Nitrogen, Phosphorus, Potassium

  • Soil types:

    • Clay: High water retention, low permeability, prone to waterlogging, nutrient-rich

    • Silt: Moderate water retention, smooth texture, easily eroded

    • Sand: High porosity, high permeability, low water retention, reduces salinization

• Soil Formation:

  • Physical processes: Weathering of rocks

  • Chemical processes: Lichen breaking down minerals

• Soil Erosion:

  • Causes: Deforestation, overgrazing, agriculture, water and wind erosion

  • Effects: Increased turbidity in water, reduced land fertility

  • Prevention: Cover crops, contour plowing, terracing, windbreaks

• Soil Horizons:

  • O - Organic matter

  • A - Topsoil

  • B - Subsoil

  • C - Parent material

  • D - Bedrock

Green Revolution

• Large-scale production methods:

  • Mechanized monocultures (efficiency but loss of biodiversity)

  • Artificial fertilizers and pesticides (increase yield but cause pollution, resistance)

  • Extensive irrigation (freshwater depletion, salinization)

  • GMOs (herbicide resistance, pest-resistant crops, ethical concerns)

Types of Farming

• Organic Farming: Uses natural fertilizers, avoids synthetic pesticides

• Industrial Farming: High-yield, large-scale, dependent on chemicals

• Subsistence Farming: Small-scale, traditional methods

Agricultural Practices and Impacts

• No-till farming: Reduces erosion, retains nutrients

• Tillage: Disrupts soil, releases CO2, increases erosion

• Crop Rotation: Enhances nutrients, disrupts pest cycles

• Monoculture: Vulnerable to pests, soil depletion

• Polyculture: Increases biodiversity, reduces pests naturally

• GMOs: Modified for higher yield and resistance

• Fertilizer Use: Increases nutrients but leads to runoff pollution

• Soil Amendments: Organic (compost) vs synthetic

• Contour Plowing: Follows land contours to reduce erosion

• Terracing: Stepped farming prevents water runoff

• Cover Cropping: Protects and enriches soil

• Slash-and-burn Agriculture: Short-term fertility, long-term land degradation

Nutrient Cycles

• Carbon Cycle: Photosynthesis, respiration, decomposition, fossil fuel combustion, sedimentation

• Nitrogen Cycle: Fixation, ammonification, nitrification, assimilation, denitrification

• Water Cycle: Evaporation, condensation, precipitation, infiltration, transpiration, runoff

• Sulfur Cycle: Weathering, volcanic emissions, decomposition, assimilation

• Phosphorus Cycle: Weathering, absorption, consumption, decomposition

• Rock Cycle: Igneous, sedimentary, metamorphic rock transformations

Pests and Pest Control

• Methods: Chemical, biological, mechanical

• Integrated Pest Management (IPM): Combines multiple methods to reduce pesticide use

• Endocrine Disruptors: Chemicals affecting hormone systems (e.g., BPA, pesticides)

• Persistent Organic Pollutants (POPs): Long-lasting, bioaccumulative chemicals (e.g., DDT, PCBs)

• Biomagnification: Toxins increase through the food chain

• Bioaccumulation: Toxins build up in organisms

• Lethal Dose (LD50): Amount needed to kill 50% of a test population

• Dose Response Curve: Graphs the effect of a substance on organisms

Sustainable Agriculture

• Definition: Farming that maintains productivity and soil health over time

• Methods:

  • Contour plowing

  • Strip cropping

  • Windbreaks

  • No-till farming

  • Crop rotation

  • Green manure

  • Limestone to adjust soil pH

  • Rotational grazing to prevent overgrazing

Irrigation Methods

• Flood Irrigation: Cheap, but high water waste and salinization

• Furrow Irrigation: Low investment, but leads to erosion and water loss

• Sprinkler Irrigation: Efficient but costly and energy-intensive

• Drip Irrigation: Low evaporation, prevents nutrient loss but expensive

• Water Issues:

  • Waterlogging: Raises water table, suffocates roots

  • Salinization: Salt accumulation in soil, harming plants

  • Aquifer depletion (e.g., Ogallala Aquifer overuse)

Meat Production Methods

• Factory Farming (CAFOs): Efficient but causes pollution, antibiotic resistance

• Free-range: Humane, less pollution, but expensive

• Grass-fed: More sustainable, but requires more land

• Environmental Impacts:

  • High land and water use

  • Greenhouse gas emissions (methane from cows)

  • Water pollution from waste runoff

Sewage Treatment

• Primary Treatment: Removes large debris (screens, sedimentation)

• Secondary Treatment: Uses bacteria to break down organic matter (aeration)

• Tertiary Treatment: Further purification (chlorination, UV light)

• Waste Management:

  • Landfills (methane release, contamination risk)

  • Agricultural use (risk of bacterial contamination, biomagnification)