Introduction to Soil Science – Key Vocabulary

A set of vocabulary flashcards covering foundational terms, concepts, and materials from the introductory lecture on soil science.

Soil

A natural mixture of inorganic and organic materials formed through weathering and conditioned by climate, organisms, topography, and time.

Soil Surface

The upper boundary of soil where it meets air, shallow water, live plants, or undecomposed plant material.

Pedon

A hexagonal column of soil (1–10 m² at the surface) used as the basic sampling unit in soil surveys.

Polypedon

A group of contiguous pedons that together form an identifiable soil series distinct from surrounding soils.

Pedological Approach

Soil study focused on describing, characterizing, and classifying soils as natural bodies, with minor emphasis on use.

Edaphological Approach

Soil study emphasizing practical use, especially relationships between soil properties and plant growth.

Soil Fertility

The capacity of a soil to supply essential nutrients for optimum plant growth.

Soil Physics

The branch dealing with soil physical properties, processes, and reactions caused by physical forces.

Soil Chemistry

The study of interactions among solid, liquid, and gaseous phases within soil.

Soil Microbiology

The study of biochemical reactions in soil primarily mediated by microorganisms.

Soil Conservation and Management

Practices to prevent soil erosion and chemical deterioration, including tillage, cropping, fertilization, and liming.

Soil Survey and Classification

Field devoted to describing soil characteristics, origins, and arranging them into a systematic taxonomy.

Soil Mineralogy

The study of the structural chemistry of a soil’s solid (mineral) components.

Land Use (Soil Science)

Allocation of land for broad purposes such as agriculture, forestry, settlements, or military reservations.

Mineral Matter

About 45 % of soil; sand, silt, and clay derived from rock weathering and supplying most nutrients except N, C, O.

Organic Matter

Roughly 5 % of soil; decayed plant and animal remains, chief natural source of nitrogen and promoter of aggregation.

Organic Soil

Soil containing more than 20 % organic matter.

Mineral Soil

Soil containing less than 20 % organic matter.

Pore Space

The voids in soil, typically 20–30 % air and 20–30 % water, essential for aeration and moisture storage.

Soil Air

Air occupying soil pores, rich in N₂ and O₂; supplies oxygen to roots and enables CO₂ exchange.

Soil Water

Water in pore spaces that carries dissolved gases, salts, and nutrients, and acts as a weathering agent.

Carbonic Acid

Weak acid formed when CO₂ dissolves in soil water, aiding mineral dissolution and nutrient release.

Soil Aeration

Exchange of gases between soil pores and the atmosphere to prevent CO₂ buildup and supply O₂ to roots.

Non-renewable Soil Resource

Recognition that natural processes need about 100 years to produce one inch of soil.

Rock

An aggregate of minerals; the primary parent material of soils.

Petrology

The scientific study of rocks.

Igneous Rock

Rock formed by solidification of molten magma (900–1600 °C) inside or outside Earth’s crust.

Granite

Light-colored acidic igneous rock rich in feldspar; common soil-forming parent material.

Diorite

Light-colored igneous rock composed mainly of feldspar and muscovite.

Gabbro

Dark-colored igneous rock dominated by biotite, hornblende, and augite.

Basalt

Basic, dark igneous rock; a dominant soil-forming rock in the Philippines.

Andesite

Intermediate volcanic rock commonly contributing to Philippine soils.

Weathering

Physical and chemical breakdown of rocks and minerals that produces parent material for soil.