Soil Science (1)

GreenEMPiRE Agriculture Reviewer: Soil Science

1. Concepts of Soil

  • Definition of Soil: A dynamic natural body on the earth's surface composed of organic and inorganic materials, where plants can grow.

  • Soil Individual:

    • Pedon: A hexagonal column of soil measuring 1-10 m² in top surface area, serving as the basic sampling unit for soil surveys.

    • Polypedon: A group of pedons identified as a series of soils with distinctive characteristics.

2. Factors of Soil Formation (CLORPT)

  • Climatic Factors: Temperature and rainfall affecting weathering and horizon development.

  • Living Organisms: Plants and organisms influence organic matter accumulation and soil texture.

  • Organic Material: Decomposition of plants and animals contributes to soil fertility.

  • Relief or Topography: Affects the movement of water and sedimentation.

  • Parent Material: The mineral or organic material from which soil develops.

3. Types of Weathering

  • Physical Weathering: Breaks rocks into smaller pieces without changing their composition (e.g., freeze-thaw cycles).

  • Chemical Weathering: Involves changes in the chemical structure of minerals (e.g., oxidation, hydrolysis).

4. Soil Composition

  • Soil Solids: Organic and mineral matter.

  • Pore Spaces: Air and water.

  • Soil Horizons: Distinct layers in the soil profile.

5. Soil Properties

  • Physical Properties:

    • Soil Texture: Refers to the proportions of sand, silt, and clay.

    • Soil Structure: Arrangement of soil particles into aggregates.

    • Bulk Density: Mass of soil per unit volume, indicating compaction.

  • Chemical Properties:

    • Soil pH: Influences nutrient availability.

    • Cation Exchange Capacity (CEC): Soil's ability to hold cations;

    • Base Saturation: Proportion of base cations to total cation capacity.

6. Soil Conservation and Management

  • Erosion Types:

    • Raindrop erosion, Sheet erosion, Rill erosion, Gully erosion.

  • Conservation Practices:

    • Contour farming: Tilling across the slope to reduce erosion.

    • Terracing: Building flat areas on sloping land to slow down water runoff.

    • Cover Cropping: Planting crops to cover soil and prevent erosion.

7. Soil Survey and Classification

  • Soil Surveys: Systematic study of soil resources.

  • Soil Classification: Grouping soils based on properties; includes orders, suborders, and series.

  • 12 Soil Orders: Entisol, Inceptisol, Aridisol, Gelisol, Mollisol, Andisol, Spodosol, Alfisol, Ultisol, Oxisol, Vertisol, Histosol.

8. Soil Fertility and Plant Nutrition

  • Essential Nutrients for Plants: Macronutrients (N, P, K) and Micronutrients (Fe, Zn, Cu).

  • Fertilizer Types: Organic and inorganic fertilizers, with specific nutrient compositions.

    • Common N Fertilizers: Urea, Ammonium sulfate.

    • Common P & K Fertilizers: Superphosphate, Muriate of Potash.

  • Fertilizer Calculations: Needed for nutrient recommendations based on soil tests.

9. Soil Analysis Methods

  • Soil Sampling: Techniques for accurately collecting soil samples to analyze nutrient content and other properties.

  • Plant tissue analysis: Correlates nutrient content in plants with soil fertility.

10. Review Questions in Soil Science

  • Basic concepts and definitions of soil science.

  • Importance of soil properties and their state in plant nutrition and agricultural management.