Soil Science and the concept of soil

Soil

Derived from the latin word “SOLUM” means floor/ground

Soil

True soil

Soil

Non-renewable

Inorganic matter

Sand, Silt & clay

Organic matter

5% is the ideal OM

Decomposition

Releases Oxygen and carbon dioxide

VV Dokuchaiev (1900)

Father of Soil Science

Whitney, 1892

Says that Soil a nutrient bin which supplies the nutrients necessary for plant growth.

VV Dokuchaiev

Soil is natural body composed of mineral and organic matter

Joffe, 1936

Soil is a dynamic natural body of mineral and organic matter that is spatially differentiated into different unconsolidated horizons of varialble depths

Brady, 1969

Says that it is a natural body that is a varialble mixture of inorganic matter derived from the weatherin and disintregation of rocks and minerals and organic matter derived from the actively and fully decomposed organic matter.

Jenny, 1941

Soil is equal to a combined influence of Climate and Organisms, modified by Relief/Topography, acting upon the Parent Material ove Significat period of Time (S=CL,O,R,PT)

Soil

A natural body with thickness and width with distinct and indistict horizontal boundaries

Components of Soil

Soil Solids 50%

Pores Spaces 50%

Soil Solids

Mineral Water (45%)

Organic Matter (5%)

Pore Spaces

Air (20-30%)

Water (20-30%)

Mineral Matter

Derived from the decomposition and disintegration of rocks and minerals; “Soil Particles”; source of most nutrients present in the soil except nitrogen, oxygen and carbon

Organic Matter

Derived from the decomposed living organisms; major source of nitrogen in the soil, thus, an indicative of N level in the soil

Air 20-30%

Primarily composed of nitrogen, oxygen and carbon dioxide; soil air is the major source of oxygen for plants; has a humdity of 100%

Carbon dioxide in soil air

Higher than atmospheric carbon dioxide with 78% N, 20% O, 0.5% CO2

Water 20-30%

Transport nutrients to the roots; causes weathering of rocks and minerals Resulting to nutrient supply; also known as the soil solution; carries and moves dissolved nutrients

Ped

A natural aggregates which continue persist when wetted and dried

Pedon

A hexagonal column

Basic unit of soil

• Ped

• Clod

• Pedon

• Polypedon

• Pedosphere

Clod

An artificial structural unit formed by cultivation

Pedon

Basic sampling unit in soil survey

Pedon

Typically used to classify soil

Polypedon

Typically used to map soil

Polypedon

Multiple pedons that has distinct characteristics that differentiate it from surrounding polypedons or within a defined limit of single soil series

Pedosphere

• the soil mantle of the Earth

• A zone of activity in which mineral, water, air and biological components come together to form soils

Air and Water content

Is depending in the moisture condition of the soil 20-30% is the ideal level

A saturated soil

Means that the pore spaces are fully occupied by water

Field of soil science

• Pedalogical

• Edaphology

Soil Science

The science that deals with soil as a natural body/resource, its pedology (classification and genesis), physical, chemical, biological and fertility characteristics in ultimate relation to crop management and production

Pedological

• Deals with the genesis, survey, classification and study of soils as a natural body. “Pedon”= Soil earth

• Science concerned with the formation, nature, ecology, classification of soil

• Study of soil's characteristics and its variations and does not focus on its immediate practical use or application

Edaphology

• Deals with the study of soils in relation to higher plants. “Edaphos”= Soil or ground

• Science concerned with the study of how soil influences human's overall use of the land and also the effect of the soil to plants

Difference of Pedalogical and Edaphology

Pedology is the study of nature or classification of soil while the edaphology is the study of soil influences human and plants

Branches of Soil Science

• Soil fertility

• Soil physics

• Soil Chemistry

• Soil Biology and ecology

• Soil Conservation and management

• Soil Survey

• Soil Genesis, Morphology and classification

• Land-Use Plannin and Classification

• Soil Mineralogy

Essential Functions of Soil

• Soil support plant growth

• Soils regulate water supply

• Soil functions as nature's recycling system

• Soils are alive and home to various and diverse organisms

• Soils influence the composition and physical condition of the atmosphere

• Foundation and structural support of engineering structure

• Preservation of earth's ecosystem

• Soils serve sas an engineering medium

Soil Fertility

• Deals with the study of the properties of the soil which enables it to provide essential chemical elements in quantities and proportions for the growth of specific plants

• Quality of sioils to provide optimum level of nutrients for plant growth

Sol physics

• Deals characteristics, properties, or interaction of soil which is caused by physical forces

• Deals with the properties and interactionof the three soil phases (soild, liquid &gas)

Soil Chemistry

• Study the various chemical reactions in the soil solution, considering that the soil is an open system

• Interaction between solid, liquid and gaseous phases of the soil

Soil Biology & Ecology

• Living organisms in the soil (bacteria, fungi, earthworms, nematodes).

• Nutrient cycling, decomposition, soil health, and ecosystem services.

Soil Conservation & Management

• Protecting soil from erosion, degradation, and pollution.

• Sustainable agriculture, watershed management, and climate adaptation.

Soil Survey

• Systematic study, description, and mapping of soils.

• Provides data for agriculture, engineering, land-use planning.

Soil Genesis, Morphology & Classification

Genesis: Soil formation processes.

Morphology: Physical appearance and profile properties.

Classification: Grouping soils based on characteristics (like USDA Soil Taxonomy, FAO, WRB).

Land-Use Planning & Classification

• Evaluating soil suitability for agriculture, forestry, urbanization, and engineering projects.

• Guides proper land utilization while preventing degradation.

Soil Mineralogy

• Minerals in soils (clays, silicates, oxides).

• Controls soil fertility, nutrient availability, and engineering properties.

two main umbrellas

Pedology-Soil Survey, Genesis, Morphology, Classification, Mineralogy.

Edaphology-Soil Biology & Ecology, Soil Conservation & Management, Land-use planning.