Soil Science Glossary

A cluster of soil particles bound together by organic matter, clay, and microbial secretions, forming the basic unit of soil structure.

Soil deposited by flowing water, typically found on floodplains and river deltas. Often fertile and well-suited for agriculture.

The mass of oven-dry soil per unit of total volume, including pore space, expressed in grams per cubic centimeter.

A quantitative measure of a soil's ability to adsorb and release positively charged ions, expressed in centimoles of charge per kilogram of soil.

A phyllosilicate mineral with particle size less than 0.002 mm. Common types include kaolinite, montmorillonite, and illite, each with different properties affecting soil behavior.

Decomposed organic material produced through aerobic biological decomposition of plant and animal residues, used as a soil amendment to improve fertility and structure.

The microbial reduction of nitrate to gaseous nitrogen compounds under anaerobic conditions, resulting in nitrogen loss from the soil system.

The branch of soil science concerned with the influence of soils on living things, particularly plants and agriculture.

The removal of dissolved or suspended material from a soil layer by the movement of water, particularly the loss of clay, iron, and organic matter from the E horizon.

The amount of water a soil holds after excess water has drained away by gravity, representing the upper limit of water available for plant use.

The stable, dark-colored organic material remaining after extensive decomposition of plant and animal residues. Highly resistant to further breakdown and critical for nutrient retention.

The accumulation of dissolved or suspended soil material in a lower horizon (typically the B horizon) after being transported downward from upper horizons.

The removal of soluble materials from soil by percolating water, transporting nutrients and contaminants downward through the profile.

A soil textural class with a balanced mix of sand, silt, and clay, generally considered ideal for agriculture due to good drainage, moisture retention, and nutrient supply.

The conversion of organic nutrients into inorganic, plant-available forms through microbial decomposition of soil organic matter.

The aerobic microbial oxidation of ammonium to nitrite and then to nitrate, making nitrogen available for plant uptake.

The branch of soil science that studies the formation, morphology, and classification of soils as natural bodies.

The ease with which water, air, and roots move through soil, determined by pore size distribution, structure, and texture.

The proportion of soil volume occupied by pore spaces (voids between particles), which hold air and water. Typically 40-60% in mineral soils.

The narrow zone of soil immediately surrounding and influenced by plant roots, characterized by intense microbial activity and chemical exchange.

The process by which soluble salts accumulate in soil to levels that inhibit plant growth, commonly caused by irrigation in arid climates.

A vertical cross-section of the soil from the surface down to bedrock, revealing the sequence of horizons formed through pedogenesis.

The USDA hierarchical system for classifying soils into 12 orders, based on diagnostic horizons, properties, and soil moisture and temperature regimes.

The overall physical condition of soil in relation to plant growth, encompassing texture, structure, consistency, porosity, and drainage.

The physical, chemical, and biological breakdown of rocks and minerals at or near the Earth's surface, producing the mineral component of soil.