Soils+and+Soil+Testing

Soils and Soil Testing

Phases of Soils

• Solid: Clay, silt, sand, organic matter

• Liquid: Soil water, dissolved minerals

• Gas: Soil air (N2, O2, CO2)

Particle Sizes and Characteristics

• Sand: Adds porosity

• Silt: Adds body to the soil

• Clay: Adds chemical & physical properties

Soil Texture Comparison

• Characteristics

  • Sand

    • Ability to Compact: Low

    • Air Space: High

    • Soil Fertility: Low

    • Water-Holding Capacity: Low

    • Workability: High

  • Silt

    • Ability to Compact: Moderate

    • Air Space: Moderate-High

    • Soil Fertility: Moderate-High

    • Water-Holding Capacity: Moderate-High

    • Workability: Moderate-High

  • Clay

    • Ability to Compact: High

    • Air Space: Low

    • Soil Fertility: Moderate-High

    • Water-Holding Capacity: High

    • Workability: Low

Soil Formation

• Horizons:

  • O horizon: Loose & partly decayed organic matter

  • A horizon: Mineral matter mixed with humus

  • E horizon: Zone of eluviation

  • B horizon: Accumulation of clay transported from above

  • C horizon: Partially altered parent material

    • Parent Material: Unweathered material

Soil Texture vs. Soil Structure

1. Soil Texture: Composition based on particle size (% sand, silt, clay)

2. Soil Structure: Arrangement of soil particles, pores, and aggregates

Soil Testing and Fertility

• Sample ID and Parameters:

  • Soil pH, Lime Requirement Index

  • Macronutrients: Phosphorus, Potassium, Magnesium, Calcium

  • Micronutrients: Zinc, Copper, Manganese, Boron, Iron

  • Estimated Cation Exchange Capacity (CEC) and Base Saturation

Importance of Soil pH

• pH affects nutrient availability and soil health

• pH Adjustments: Use of limestone to neutralize acidity

Summary

• Soil consists of mineral (sand, silt, clay) and organic matter

• Components aggregate to create soil structure

• Soil testing provides essential information on mineral nutrients for plant health