Lecture 14 Soil Nitrogen, Phosphorus, and Potassium Cycles

These flashcards cover essential vocabulary and processes related to the nitrogen, phosphorus, and potassium cycles in soil, significant for understanding nutrient management in agriculture.

Nitrogen Fixation

The chemical reaction that converts dinitrogen gas (N2) to ammonia (NH3).

Nitrification

The process where ammonium (NH4+) is oxidized by bacteria to produce nitrate (NO3-).

Denitrification

The multi-step process performed by bacteria that converts nitrate (NO3-) to nitrogen gas (N2) under anaerobic conditions.

Volatilization

The process where ammonium in soil is converted to ammonia gas, which can escape into the atmosphere.

Immobilization

The conversion of inorganic nutrients into organic forms by microorganisms, preventing plants from accessing these nutrients.

Mineralization

The process by which soil microorganisms decompose organic matter, releasing simpler chemical forms of nitrogen into the soil.

Phosphorus Fixation

Chemical processes that render phosphorus unavailable to plants, often involving precipitation reactions and adsorption to mineral surfaces.

C:N Ratio

The ratio of carbon to nitrogen in organic matter, which influences net nitrogen mineralization and immobilization.

Soil pH

A measure that affects the availability of phosphorus to plants.

K Cycle

The cycle involving both organic and inorganic potassium inputs and losses, important for crop production.

Eutrophication

The process by which water bodies receive excess nutrients, leading to overgrowth of algae and depletion of oxygen.

Biological Nitrogen Fixation

A natural process where certain organisms convert atmospheric nitrogen into a form usable by plants, primarily through legume-rhizobia symbiosis.