Nutrient Management Flashcards Preview

Agriculture > Nutrient Management > Flashcards

Flashcards in Nutrient Management Deck (107)
Loading flashcards...

Macronutrients (type/mobility in plants/uptake form)

Nitrogen (NH4+, NO3-) mobile

Phosphorus (H2PO4-, HPO4^2-) mobile

Potassium (K+) mobile

Calcium (Ca^2+) immobile

Magnesium (Mg^2+) mobile

Sulfur (SO4^2-) immobile


Micronutrients (name/uptake form)

Boron (H3BO3, H2BO3^-)

Chlorine (Cl-)

Copper (Cu2+)

Iron (Fe^2+, Fe^3+)

Manganese (Mn^2+)

Molybdenum (MoO4^2-)

Nickel (Ni^2+)

Zinc (Zn^2+)


Function of Nitrogen

Used in synthesis of amino acids, proteins enzymes

Found in chlorophyll (photosynthesis)

ADP, ATP (energy transfer)


Function of Phosphorus

Important component of energy transfer system (ADP, ATP)

Important to photosynthesis and respiration

Part of cell nuclear material important to cell division


Function of Potassium

Accelerated growth of meristematic tissue

Regulation of stomata open ring (water loss)

Involved in N and carb metabolism
Catalyze some enzymes


Function of Sulfur

A component of several amino acids (cystine,cysteine, methionine) which are part of many proteins

Involved in protein synthesis and enzyme activation

Forms flavor compounds in mustard, garlic, and onions


How does nutrient need change as plant growth progresses from germination to maturity

Plant nutrient demands gradually increase during the seedling stage, rapidly increases during vegetative growth, and decreases again as reproductive growth dominates


What is the role of soil solution in supplying nutrients from the soil

Plant nutrients dissolved in the soil solution and are made available for plant absorption through the processes of mass flow, diffusion, and roof interception


What is the role of cation exchange sites in supplying nutrients from the soil

Cation exchange sites located on clay particles and organic matter hold cations and can be released into the soil solution to be readily available to plants


What is the role of organic matter in supplying nutrients from the soil

Can be a source of nutrients (N, P, K) when decomposed

Holds onto cations by cation exchange and chelation


What is the role of soil minerals in supplying nutrients from the soil

Dissolved soil minerals can release nutrients into the soil solution

Clays, carbonates, and hydroxides can also retain nutrients by adsorption on their surfaces


What is the role of plant residue in supplying plant nutrients from the soil

Plant residue contains the essential elements that are returned to the soil system as the plant residue decomposes and rainfall leaches soluble nutrients from the plant residue


Describe nutrient mineralization

The release of a nutrient when an organic material (SOM, manure, biosolids) is decomposed by soil microorganisms

It is the conversion of a nutrient from organic to inorganic form


Describe immobilization

When a nutrient is converted from an inorganic to organic form

During decomposition, the nutrient is incorporated into microbial cells and SOM


Describe uptake antagonism between ions

Two or more ions may compete for plant uptake by various mechanisms

One ion is said to be more antagonistic with regard to the uptake of another ion


Describe mass flow

Occurs when a nutrient moves to a plant root with the water that is being absorbed by the plant

Important uptake process for N, Ca, Mg


Describe Diffusion

The movement of a nutrient to a plant root due to a concentration gradient between the soil solution and the root surface. The nutrient concentration is higher in the soil solution than at the root surface so the nutrient moves to the root surface

Important nutrient uptake process go P, K


Describe root interception

Occurs when a root grows next to a clay or OM surface and absorbs the nutrients.

Usually means the root has grown near a soil colloid and absorbed the nutrients on or near the colloid surface

Usually a minor way nutrients are absorbed


How does soil nutrient uptake occur at the root surface

Passive (nutrient enters root with water that is being absorbed)

Active processes where the nutrient is moved into the by a molecule or ion termed a carrier


Define Cation exchange capacity

The amount of positively charged cations that can be held by a given weight of soil

Units are color+charge/kg of soil (equivalent to meq/100 g soil)


How does CEC influence nutrient mobility of cations and anions

As CEC increases , the mobility of cations decreases as they are held on the cation exchange sites.

Leaching of soluble anions (nitrate, chloride, sulfate) increases as CEC increases.


What influences CEC

Increases in Clay mineral type (1:1 vs 2:1 clays), organic matter and soil pH generally increase CEC


What cations are retained on cation exchange sites

Calcium, Magnesium, and Potassium.

Can become immobile.

I’d routine additions of a cation occur, the added cation can change places with Ca, Mg, or K on the CEC releasing them into the soil solution.


What forms of Nitrogen are mobile and immobile in the soil

Nitrate (NO3-) is mobile

Ammonium (NH4+) is immobile


Explain when phosphate is mobile/ immobile in the soil

Phosphate is immobile in soil except where P sprouting capacity has been exceeded


Is sulfate mobile or immobile in the soi?



When are cations mobile/immobile in the soil?

When on exchange sites, Ca, Mg, and K are immobile.

When cations are in the soil solution they are mobile


Describe how texture affects nutrient uptake

The more clay in a soil, the more likely there will be available nutrients.

Leaching of nutrients increases as souls become more sandy because sandy soils have larger pores allowing fewer water movement and have a small cation and anion exchange capacity


Describe how structure affects nutrient uptake

Soil structures that create large pores will increase the potential for nutrient losses through leaching

Lack of structure can lead to increases in runoff and erosion


Describe how drainage/aeration affect nutrient uptake

If drainage is poor, anaerobic conditions may occur, causing increased solubility in Iron and Manganese and the loss of nitrate by denitrification

Nutrient losses are associated with excessive drainage