Soil Science

Study of soil properties, fertility, and management.

13 topics and 151 published lessons.

Foundations of Soil Science

Definitions of soil, pedological and edaphological approaches, soil individuals, phases, mineral and organic soils, functions, quality, health, and degradation.

6 published lessons

  • Soil as a Natural Body and Natural Resource
  • Pedological and Edaphological Concepts of Soil
  • Soil Individuals and Soil Bodies
  • Major Components and Phases of Soil
  • Mineral Soils and Organic Soils
  • Soil Quality, Soil Health, and Soil Degradation

Minerals, Rocks, Weathering, and Parent Materials

Minerals, rock groups, weathering processes, parent materials, nutrient-bearing minerals, and the relationship of geological materials to soil development.

9 published lessons

  • Minerals and Their Diagnostic Properties
  • Primary and Secondary Minerals
  • Rocks and the Rock Cycle
  • Igneous Rocks and Their Agricultural Significance
  • Sedimentary and Metamorphic Rocks
  • Physical Weathering
  • Chemical Weathering
  • Biological Weathering
  • Soil Parent Materials

Soil Formation, Pedogenic Processes, and Profiles

Soil-forming factors, soil sequences, additions, losses, transformations, translocations, specific pedogenic processes, tropical profiles, master horizons, and horizon notation.

9 published lessons

  • Factors of Soil Formation
  • Climate as a Soil-Forming Factor
  • Organisms and Vegetation in Soil Formation
  • Relief, Topography, and Drainage
  • Time and Soil Development
  • Fundamental Pedogenic Processes
  • Specific Soil-Forming Processes
  • Soil Profile, Solum, and Regolith
  • Master Horizons and Horizon Designation

Soil Texture, Structure, Density, Porosity, and Morphology

Particle size, textural classes, field and laboratory texture determination, structure, aggregation, puddling, density, porosity, consistence, compaction, color, and drainage indicators.

15 published lessons

  • Soil Particle-Size Fractions
  • Soil Textural Classes and the Textural Triangle
  • Field Determination of Soil Texture
  • Mechanical Analysis of Soil Texture
  • Soil Texture and Crop Suitability
  • Soil Structure and Structural Units
  • Soil Aggregation and Aggregate Stability
  • Soil Structure Management and Puddling
  • Particle Density
  • Bulk Density
  • Bulk-Density Computations
  • Soil Porosity and Pore Classification
  • Soil Consistence, Tilth, and Compaction
  • Soil Color and the Munsell System
  • Redoximorphic Features and Drainage Interpretation

Soil Water, Aeration, Temperature, and Submerged Soils

Water cycle, water retention, potentials, moisture constants, water movement, measurement, aeration, soil temperature, submerged soil chemistry, lowland conditions, and coastal limitations.

12 published lessons

  • Soil Water and the Hydrologic Cycle
  • Forces Holding Water in Soil
  • Soil-Water Potential
  • Soil-Moisture Constants
  • Soil-Water Retention Curves
  • Soil-Moisture Content Calculations
  • Infiltration, Percolation, and Capillary Movement
  • Saturated and Unsaturated Water Flow
  • Measuring Soil-Moisture Status
  • Soil Aeration and Gas Exchange
  • Soil Temperature
  • Submerged, Lowland, and Coastal Soils

Soil Colloids, Clay Mineralogy, and Ion Exchange

Soil colloids, silicate clay structures, non-crystalline minerals, oxides, humus, charge development, adsorption, ion exchange, CEC, base saturation, and ESP.

12 published lessons

  • Soil Colloids and Specific Surface Area
  • Tetrahedral and Octahedral Sheets
  • One-to-One Clay Minerals
  • Expanding Two-to-One Clay Minerals
  • Vermiculite, Illite, and Chlorite
  • Noncrystalline Minerals and Oxides
  • Humus as an Organic Colloid
  • Permanent and Variable Charge
  • Ion Adsorption and Exchange
  • Cation Selectivity and Exchange Reactions
  • Cation Exchange Capacity
  • CEC, Base Saturation, and ESP Computations

Soil pH, Acidity, Liming, Salinity, and Sodicity

Soil reaction, nutrient availability, acidity pools, buffering, liming materials, lime requirement, acid soil amendments, calcareous soils, salinity, sodicity, and reclamation.

13 published lessons

  • Soil pH and the pH Scale
  • Soil pH and Nutrient Availability
  • Sources and Development of Soil Acidity
  • Pools of Soil Acidity
  • Soil Buffering Capacity
  • Liming Materials
  • Lime Requirement and Liming Decisions
  • Effects and Risks of Liming
  • Gypsum and Other Acid-Soil Amendments
  • Soil Alkalinity and Calcareous Soils
  • Salinity, Sodicity, EC, SAR, and ESP
  • Saline, Sodic, and Saline-Sodic Soils
  • Reclamation of Salt-Affected Soils

Soil Organisms, Organic Matter, and Composting

Soil food webs, macroorganisms, microorganisms, rhizosphere biology, mycorrhizae, organic matter pools, decomposition, C:N ratio, nutrient transformations, composting, and organic fertilizer quality

11 published lessons

  • Soil Organisms and the Soil Food Web
  • Earthworms and Other Soil Macroorganisms
  • Soil Bacteria and Archaea
  • Soil Fungi, Actinomycetes, Algae, and Protozoa
  • Rhizosphere, Mycorrhizae, and Beneficial Microorganisms
  • Soil Organic Matter Fractions and Pools
  • Effects of Organic Matter on Soil Properties
  • Organic Matter Decomposition
  • Carbon-to-Nitrogen Ratio, Mineralization, and Immobilization
  • Nitrogen, Phosphorus, and Sulfur Transformations
  • Composting and Organic-Fertilizer Quality

Plant Nutrition and Soil Fertility

Fertility versus productivity, essentiality, macro and micronutrients, nutrient functions, mobility, corn deficiency symptoms, nutrient forms, availability, movement to roots, uptake, response laws, soil testing, and plant analysis.

15 published lessons

  • Soil Fertility and Soil Productivity
  • Criteria of Nutrient Essentiality
  • Classification of Plant Nutrients
  • Nitrogen, Phosphorus, and Potassium Functions
  • Calcium, Magnesium, and Sulfur Functions
  • Micronutrient Functions
  • Nutrient Mobility and Deficiency-Symptom Location
  • Nitrogen, Phosphorus, and Potassium Deficiency in Corn
  • Nutrient Forms and Availability in Soil
  • Nutrient Movement to Root Surfaces
  • Nutrient Uptake by Roots
  • Factors Limiting Nutrient Availability and Uptake
  • Liebig's Law and Nutrient-Response Curves
  • Soil Sampling and Soil Testing
  • Plant Analysis and Integrated Diagnosis

Fertilizers and Nutrient Management

Fertilizer terminology, nutrient carriers, organic and inorganic sources, grades, ratios, blends, conversions, inorganic and organic requirement calculations, placement, timing, and integrated nutrient management.

13 published lessons

  • Fertilizer Terminology and Grade
  • Nitrogen Fertilizers
  • Phosphorus Fertilizers
  • Potassium Fertilizers
  • Secondary and Micronutrient Fertilizers
  • Organic Fertilizers and Manures
  • Computing Nutrient Requirement from Fertilizer Grade
  • Fertilizer Grade, Ratio, and Blend Computations
  • Elemental and Oxide Conversions
  • Organic-Fertilizer Requirement Computations
  • Fertilizer Placement Methods
  • Timing and Split Application
  • Integrated Nutrient Management and the 4R Principle

Soil Erosion, Conservation, and Land Management

Erosion mechanics, water and wind erosion, erosivity, erodibility, slope effects, USLE, biological and engineering measures, conservation tillage, upland and lowland fertility protection, and restoration.

11 published lessons

  • Soil Erosion Processes
  • Forms of Water Erosion
  • Erosivity and Erodibility
  • Effects of Slope on Soil Fertility Loss
  • Universal Soil Loss Equation
  • Agronomic and Biological Conservation Measures
  • Mechanical and Engineering Conservation Measures
  • Conservation Tillage and Soil-Cover Management
  • Upland Soil-Fertility Conservation
  • Lowland Soil-Fertility Management
  • Restoration of Degraded Soils

Soil Survey, Classification, and Land Evaluation

Survey purposes, procedures, mapping units, taxonomic categories, diagnostic horizons, moisture and temperature regimes, the twelve soil orders, family and series, land capability, and land suitability.

12 published lessons

  • Purpose and Uses of Soil Survey
  • Soil-Survey Procedures
  • Soil Mapping Units and Map Scale
  • Principles and Categories of Soil Taxonomy
  • Diagnostic Surface Horizons
  • Diagnostic Subsurface Horizons
  • Soil Moisture and Temperature Regimes
  • The Twelve Soil Orders
  • Recognition of Agriculturally Important Soil Orders
  • Soil Family and Soil Series
  • Land Capability Classification
  • Land Suitability Evaluation

Integrated Philippine Soil Management

Upland, irrigated rice, coastal, beach, volcanic, acid tropical, and degraded soil cases; integrated diagnosis; computation; and management recommendations.

7 published lessons

  • Upland Crop Soil Selection and Management
  • Irrigated-Rice Soil Selection and Management
  • Coastal, Beach, and Salt-Affected Agricultural Soils
  • Volcanic Soils and Andic Properties
  • Acid Upland Soils in Humid Tropical Areas
  • Integrated Soil Diagnosis Cases
  • Comprehensive Soil Science Problem Solving