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New Jersey Envirothon

Soils Study Guide

​Out of the long list of nature's gifts to man, none is perhaps so utterly essential to human life as soil.

Hugh Hammond Bennett

The soil forming factors supply the initial material and conditions under which a particular soil will form. The soil forming processes result from the interactions of the soil forming factors. These processes influence and even create a soil’s physical and chemical properties.

Introduction

Soils are important because they perform many important functions, including:

  • Sustaining biological activity, diversity, and productivity
  • Regulating and partitioning water and solute flow
  • Filtering, buffering, degrading, immobilizing and detoxifying organic & inorganic materials
  • Storing and cycling nutrients and other elements
  • Providing support of socioeconomic structures

1. Functions of Soils

​Soils vary from place to place due to differences in their Soil forming factors, Soil forming processes, and/or Soil properties:

2: Variability of Soils

A: Soil Forming Factors

(See “From the Surface Down”, section 2)

  1. Parent material
  2. Climate
  3. Organisms
  4. Landscape position
  5. Time

B: Soil Forming Processes​

(See “From the Surface Down”, section 3)

  1. Additions
  2. Losses
  3. Translocations
  4. Transformations

C: Soil Properties

Soil physical properties

  1. Horizonation
  2. Soil Color
  3. Soil Texture
  4. Soil Structure
  5. Soil Consistence
  6. Bulk Density

Soil chemical properties

  1. Cation Exchange Capacity
  2. Soil Reaction (pH)

References:

Reference: NRCS Soil Quality Institute website

Surficial geology and bedrock geology maps, and geologic information is available from New Jersey Geological Survey website.

From The Surface Down

Measuring stick against a soil profile displaying the different soil horizons
Photograph Credit: Schoenagel III, Fred C. NRCS, Resource Soil Scientist & Robinson, Timothy J. BSCD, Natural Resource Specialist “Downer Soil Profile” 2013. Photograph. Tabernacle, New Jersey.

Phases of Soil

​In their natural setting, soils exist as a “three-phase” system comprised of a:

  1. “solid phase” – the soil matrix; includes inorganic material with various chemical and mineralogical properties, and organic material in varying degrees of decomposition
  2. “liquid phase” – the soil solution; includes soil water and its dissolved substances
  3. “gaseous phase” – the soil air; more variable in composition than the air above the soil


An ideal soil contains:

  • 50% solid matter, of which 45% is mineral soil material and 5% is organic soil material
  • 50% pore space, of which 25% is soil water and 25% is soil air

3: The Soil Environment

  • Water Movement in Soils
  • Effects of Saturation by Water on Soils
  • Fragipans

4: Special Topics on Soils