Soil Organisms and Nutrient Cycling

Flashcards covering key terms and concepts related to soil organisms, nutrient cycling, and environmental impacts.

Cation exchange capacity (CEC)

The ability of soil to hold and exchange cations, which are positively charged ions.

Epigeic earthworms

Relatively small earthworms that live in the litter layer and consume litter without mixing it with mineral soil.

Endogeic earthworms

Earthworms that inhabit the upper layer of mineral soil and create horizontal burrows.

Anecic earthworms

Large earthworms that make vertical burrows and feed at the surface, bringing litter into their burrows.

Soil organic matter (SOM)

A mixture of plant and animal matter, microorganisms, and organic compounds that contributes to soil fertility.

Mineralization

The process by which organic nitrogen is converted to plant-available forms, such as ammonium (NH4+).

Nitrification

The biological process in which ammonium (NH4+) is converted into nitrate (NO3-) by nitrifying bacteria.

Denitrification

The reduction of nitrate (NO3-) to nitrogen gas (N2) or nitrous oxide (N2O) by denitrifying bacteria.

Mycorrhizae

Symbiotic associations between fungi and plant roots that enhance nutrient and water uptake for the plant.

Turnover rate

The rate at which a given pool of nutrients is replaced or turned over in the ecosystem.

Residue time

The average length of time that a substance remains in a particular pool or compartment.

Eutrophication

The process by which water bodies become overly enriched with nutrients, often leading to excessive growth of algae.

Carbon cycle

The series of processes by which carbon compounds are interconverted in the environment.

Nitrogen cycle

The series of processes by which nitrogen and its compounds are interconverted in the environment, including fixation, mineralization, nitrification, and denitrification.

Phosphorous cycle

The cycle of phosphorous in the environment, involving its uptake by plants, movement through soil, and buildup in sediments.

Soil microorganisms

Diverse and numerous organisms present in soil that play critical roles in nutrient cycling and soil health.

Greenhouse gases

Gases that trap heat in the atmosphere, including carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O).

Turnover rate of nutrients

The proportion of the nutrient pool that is cycled or replaced during a specific time period.