“The Soil is God’s Gift to the Living”- Thomas Jefferson

Soil Formation Factors and Management  

Natural FactorsClORPTClimateOrganic MaterialReliefParent MaterialTime 

The Human Factor  

Soil Sampling and Mapping Units

Figure 15.1

A nearly mature profile….10,000 years in the making

Figure 15.2

O

A

E

B

Soil PropertiesColor 

An indication of material in the soil Texture  

An indication of the amount of weatheringStructure  

An indication of its chemical and physical properties of the parent material

Consistence  An indication of its structural integrity

Porosity  Related to texture – an indication of grain size

MoistureAn indication of the environment it is in  

Soil Texture Triangle

Figure 15.3

Types of Soil Structure

Figure 15.4

Soil Colloids and Cation Exchange Capacity

Figure 15.5

Soil Moisture and Cation Exchange Capacity

pH Scale and Soils

Figure 15.6

Soil ClassificationSoil Taxonomy  

Classification of soils based on observed properties

Diagnostic Soil Horizons

Usually the O, A, E, B horizons  

The 12 Major Soil Orders of the Soil Taxonomy

Zonal Soils

Oxisols

Ultisols

Alfisols

Mollisols

Aridisols

Azonal Soils

Entisols

Inceptisols

Andisols

Vertisols

Histosols

Gelisols(Page 500 in your text)

Soil Taxonomy

Figure 15.8

The Factors Forming the Koeppen System

Figure 6.5

Pedogenic RegimesLaterization

Movement of water freely through soilsSalinization

Arid environments, water evaporates leaving salts to build up in soils

CalcificationMovement of calcium through the soil through capillary water

PodzolizationSlower movement of water through soils allowing for build-up of strongly zonal soils with water-logged lower horizons

GleizationIn cold environments, slow decomposition of organic material allowing it to build up over time.

Temperature

Moi

stur

e

Laterization

Salinization

Calcification

Gleization

Podzolization

Laterization

A – very little minerals left

Hot temperatures allow decomposers and plant roots to remove organic material quickly

B – only clay (sesquioxides) remainOrange to red color comes from rusting of iron

Nearly all minerals are leached out – even sands and silts are washed away leaving only thick clay layer

Heavy Rainfall

Oxisols “Terra Rosa”

Figures 15.9, 15.11

Ultisols

Figure 15.19

Podzolization Process

Figure 15.20

Alfisols

Figure 15.18

Spodosols

Figure 15.20

Calcification in soil

Figure 15.17

Mollisols

Figures 15.14, 15.15

Mollisols

Figure 15.16

Aridisols

Figures 15.12, 15.13

Vertisols – an azonal soil

Figures 15.24, 15.25

Histosols – another azonal soil

Figure 15.26

Gelisols

Figure 15.22

Soil Degradation

Figure 15.7