Agriculture

• Soil

  The upper layer of the earth in which plants grow, consisting of a mixture of organic remains, clay, rock and rock particles
• Importance of soil


  • Serves as a medium for plant growth
  • Helps modify the atmosphere by emitting and absorbing gases
  • Provides habitats for animals like earthworms
  • Absorbs, releases, alters and purifies water
  • Serves as an engineering media for construction
  • Acts as a living filter to clean water
• Components of soil

  • Mineral particles
  • Organic content (living plants, animals, microorganisms, dead remains)
  • Air
  • Water
• Composition of soil by volume

  • Organic matter - 5%
  • Air - 25%
  • Water - 25%
  • Mineral matter - 45%
• Composition of soil by weight

  • Organic content - 3%
  • Mineral matter - 85%
• Soil particle sizes

  • Sand - 2mm to 0.06mm
  • Silt - 0.06mm to 0.002mm
  • Clay - less than 0.002mm
• Importance of soil minerals for plant growth

  • Nitrogen - for protein synthesis
  • Phosphorus - for respiration and cell membranes
  • Potassium - for respiration and photosynthesis
  • Magnesium - for chlorophyll production
• Soil organic matter

  Provides organic nutrients needed for plant growth
• Soil pH

  Measure of acidity or alkalinity, affects suitability of plants
• Types of agriculture

  • Arable farming (growing crops)
  • Pastoral farming (rearing livestock)
  • Mixed farming (growing crops and rearing livestock)
• Farming based on purpose

  • Commercial farming (to make profit)
  • Subsistence farming (to produce food for the farmer and family)
• Farming based on inputs

  • Intensive farming (small land, high inputs)
  • Extensive farming (large land, low inputs)
• Techniques to increase agricultural yield

  • Crop rotation
  • Use of fertilizers
  • Irrigation
  • Insect/weed/fungus control
  • Mechanization
  • Selective breeding
  • Genetically modified organisms
  • Controlled environments (greenhouses, hydroponics)
• Methods of insect control

  • Insecticide
  • Cultural control
  • Biological control
• Methods of weed control

  • Herbicide
• Methods of fungi control

  • Fungicide
• Mechanization

  Using machinery to improve crop production and reduce human labor
• Agricultural practices

  • Selective breeding of animals and plants
  • Genetically modified organisms
  • Controlled environments (greenhouses, hydroponics)
• Hydroponics is the process of growing crops in the absence of soil
• Impacts of agricultural practices

  • Insecticide and herbicide resistance
  • Environmental damage (killing useful insects, spray drift, leaching)
  • Overuse of fertilizers (eutrophication, soil pH changes)
• Eutrophication

  1. Excessive nutrients from fertilizers flushed into water bodies

  2. Algae bloom

  3. Reduced sunlight and oxygen for aquatic plants

  4. Decomposition of dead plants and animals depletes oxygen

  5. Ecosystem collapse
• Impacts of irrigation

  • Soil structure damage
  • Nutrient leaching
  • Soil erosion
  • Soil salinization
  • Waterlogging
• Soil erosion

  Removal of topsoil by water and wind, caused by loss of vegetation from over-cultivation and overgrazing
• Impacts of soil erosion

  • Loss of habitat
  • Desertification
  • Silting of rivers
  • Displacement of people
  • Malnutrition and famine
• Strategies to reduce soil erosion

  • Terracing
  • Contour ploughing
  • Windbreaks
  • Maintaining vegetation
  • Adding organic matter
  • Crop rotation
• Strategies for sustainable agriculture

  • Organic fertilizers
  • Managed grazing
  • Crop rotation
  • Pest and drought resistant crops
  • Drip irrigation
  • Rainwater harvesting
• Monoculture


  A farming practice where a single crop or plant species is grown on a large scale, potentially leading to loss of biodiversity and ecosystem resilience
• Organic Fertilizers


  Improve soil health, reduce environmental pollution, increase crop yields, and promote food safety through eco-friendly agricultural practices
• Managed Grazing


  Promotes soil conservation, biodiversity, carbon sequestration, and sustainable land use through strategic grazing management
• Crop Rotation


  Improves soil fertility, manages pests and diseases, increases crop yields, and promotes ecosystem services through strategic crop planning
• Pest and Drought Resistant Crops

  Improve yield stability, reduce chemical use, and promote ecosystem resilience through genetic resistance to pests and drought
• Drip Irrigation


  Conserves water, improves soil health, and optimizes crop yields through targeted water delivery
• Rainwater Harvesting


  Conserves water, increases water security, promotes ecosystem services, and reduces costs through targeted rainwater collection
• Organic Fertilizers


  Higher cost, limited availability, and variable effectiveness of organic fertilizers can limit their adoption
• Managed Grazing


  Complexity, conflicting land uses, and initial investment can limit the adoption of managed grazing
• Crop Rotation


  Complexity, variability, and land dedication can make crop rotation challenging to implement
• Pest and Drought Resistant Crops


  Dependence on technology, potential for unintended consequences, and biotechnology risks can limit the adoption of genetically modified crops
• Drip Irrigation


  Initial cost, complexity, and maintenance requirements can make drip irrigation challenging to implement
• Rainwater Harvesting


  Initial cost, maintenance requirements, and proper siting and design challenges can limit the adoption of rainwater harvesting
• Crop Rotation


  Improves soil fertility, manages pests and diseases, and promotes crop diversity