Nutrient Management

Question 1

What are the essential nutrients obtained from the air as carbon dioxide and as water?

Answer 1

Carbon(C) Hydrogen(H) and Oxygen(O)

Question 2

List the Macronutrients along with their symbol

Answer 2

Nitrogen(N), Phosphorus(P), Potassium(K), Calcium(Ca), Magnesium(Mg), Sulfur(S)

Question 3

Which Macronutrients are Mobile in the Plant?

Answer 3

Nitrogen, Phosphorus, Potassium, Magnessium

Question 4

Nitrogen’s Uptake forms in soil

Answer 4

Ammonium ion (NH4+), Nitrate ion (NO3-)

Question 5

Phosphorus’s uptake forms in soil

Answer 5

Phosphate ion (H2PO4-, HPO42-)

Question 6

Potassium’s uptake forms in soil

Answer 6

Potassium ion (K+)

Question 7

Calcium’s uptake forms in soil

Answer 7

Calcium ion (CA2+)

Question 8

Magnesium’s uptake forms in soil

Answer 8

Magnesium ion (MG2+)

Question 9

Sulfur’s uptake forms in soil

Answer 9

Sulfate ion (SO42-)

Question 10

List Micronutrients along with their symbol

Answer 10

Boron(B), Chlorine(Cl), Copper(Cu), Iron(Fe), Manganese(Mn), Molybdenum(Mo), Nickel(Ni), Zinc(Zn)

Question 11

Boron’s uptake forms in soil

Answer 11

Boric Acid (H3BO3) or borate ion (H2BO3-)

Question 12

Chlorine’s uptake forms in soil

Answer 12

Chloride ion (CL-)

Question 13

Copper’s uptake forms in soil

Answer 13

Cupric ion (CU2+)

Question 14

Iron’s uptake forms in soil

Answer 14

Primarily ferrous ion (Fe2+): some Ferric ion (FE3+)

Question 15

Manganese’s uptake forms in soil

Answer 15

Primarily manganous ion (Mn2+)

Question 16

Molybdenum’s uptake forms in soil

Answer 16

Molybdate ion MoO42-)

Question 17

Nickel’s uptake forms in soil

Answer 17

Nickel ion (Ni2+)

Question 18

Zinc’s uptake forms in soil

Answer 18

Zinc ion (Zn2+)

Question 19

Describe the function of Nitrogen in plants

Answer 19

It is used in the synthesis of amino acids, proteins, enzymes; found in chlorophyll ((photosynthesis)Green), ADP and ATP(energy transfer)

Question 20

Describe the function of Phosphorus in plants

Answer 20

important component of energy transfer system(ADP,ATP); important to photosynthesis and respiration; part of cell nuclear material important to cell division

Question 21

Describe the function of Potassium in plants

Answer 21

accelerates growth of meristematic tissue; regulation of somatal opening (water loss); incolved in nitrogen and carbohydrate metabolism; catalyzes some enzymes

Question 22

Describe the function of Sulfur in plants

Answer 22

is a component of several amino acids (cystine, cysteine, methionne) which are part of many proteins; involved in protein sythesis and enzyme activation; forms flavor compounds in mustard, garlic, and onions.

Question 23

Describe of nutrient needs change as plant growth progresses from germination to maturity

Answer 23

During the seedling stage, plants are small and nutrient demand is small. As the plants become larger through the vegetative growth stages nutrient needs increase. Nutrient needs can be high in reproductive tissues, but much of that demand is met by redistribution of nutrients that are contained in vegetative tissues.

Question 24

Describe soil solution

Answer 24

Soil solution is the water in soil that contains dissolved ions, molecules, and gases. Plant nutrients dissolved in the soil solution can be cations, anions, or uncharged molecules. These nutrients are absorbed by the plant roots through the processes of mass flow, diffusion, abd root interception

Question 25

Describe cation exchange sites

Answer 25

Positively charged ions, cations, are held by cation exchange sites on soil clay and organic matter. These cations can move into the soil solution by cation exchange and be readily available to plants.

Question 26

Describe organic matter

Answer 26

Soil organic matter can retain cationic nutrients by cation exchange and chelation, and can be a source of nutrients (N,P,S) when decomposed.

Question 27

Describe soil minerals

Answer 27

Soils contain minerals that slowly dissolve to release nutrients to the soil solution. Some soil minerals (e.g. clays, carbonates, hydroxides) can also retain nutrients by adsorption on their surfaces

Question 28

Describe plant residue

Answer 28

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

Question 29

Describe mineralization

Answer 29

Mineralization is the release of a nutrient when an organic material (e.g. soil organic matter, manure, biosolids) is decomposed by soil microorganisms. It is the conversion of a nutrient from organic to inorganic form

Question 30

Describe immobilization

Answer 30

Immobilization is the reverse of mineralization(nutrient is converted from inorganic to organic form). During decomposition the nutrient is incorporated into microbial cells and soil organic matter.

Question 31

Describe uptake antagonism between ions

Answer 31

Two or more ions may compete for plant uptake by various mechanisms. One ion is said to be antagonistic with regard to the uptake of another ion.

Question 32

Describe mass flow

Answer 32

Mass flow occurs when a nutrient moves to a plant root with the water that is being absorbed by the plant. This is important nutrient uptake process for nutrients such as nitrogen, calcium, and magnesium

Question 33

Describe diffusion

Answer 33

Diffusion is 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 and, thus, the nutrient moves to the root surface. This is an important nutrient uptake process for nutrients such as phosphorus and potassium.

Question 34

Describe root interception

Answer 34

Root interception occurs when a root grows next to clay or organic matter surface and absorbs the nutrient. Root interception usually means the root has grown near a soil colloid and absorbed the nutrients on or near the colloid surface. This is usually a minor way nutrients are absorbed

Question 35

Descibe how cation exchange capacity (CEC) influences nutrient mobility of cations and anions

Answer 35

Cation exchange is the process whereby cation(s) in the soil solution change places with cation(s) on a negatively charged soil colloid (clay and organic matter) *This is an important reaction because the cations in solution are the ones that are absorbed by the plant and the ones than can leach.
Ca2+ + k+[soil colloid] = 2k+ + Ca2+[soil colloid]

Question 36

Describe CEC

Answer 36

is the amount of positively charged cations that can be held by a given weight of soil. Units are cmaole + charge per kg soil which is equivalent to meq/100 g soil.

Question 37

What happens as Cation exchange capacity increases?

Answer 37

The mobility of cations decreases as they are held on the CEC. Increases in 2:1 clay minerals, organic matter, and soil pH are generally related to increases in CEC

Question 38

List the three cations that are largely retained on the CEC of a soil and are immobile

Answer 38

Calcium (Ca), Magnesium (mg), and Potassium (K)

Question 39

If routine additions of cations occur (e.g. fertilization, liming, or acidification), the added cation(s) can change place with

Answer 39

Ca, Mg, or K on the CEC bringing Ca, Mg, or K into the soil solution. Any cation in the soil solution is mobile and subject to leaching

Question 40

What type of anions are not evenly distributed in soil water and why?

Answer 40

Soluble anions (nitrate, chloride, and sulfate) because they are excluded from water nearest negatively charged clay and organic matter. The water that contains the excluded anions also moves fastest in soil. The net effect is that soluble anion leaching is increased

Question 41

Nitrogen is mobile as what and immobile as what?

Answer 41

Mobile as nitrate(NO3-) immobile as ammonium (NH4+)

Question 42

Phosphate (H2PO4-, HPO42-) is immobile in soil except

Answer 42

where P sorption capacity has been exceeded

Question 43

Is Sulfate (SO42-) mobile or immobile in most soils?

Answer 43

Mobile

Question 44

Calcium Magnesium and Potassium are immobile in what and mobile in what?

Answer 44

Immobile in CEC and Mobile in soil solution

Question 45

Describe how texture affects nutrient uptake

Answer 45

Texture is the proportion of sand, silt, and clay in a soil. **Available plant nutrients are generally held in the clay fraction, so the more clay in a soil the more likely there will be available nutrients.* Leaching of nutrients increases as soils become more sandy because sandy soils have large pores that allow freer water movement. Sandy soils also have only a small capacity to retain ions due to small cation and anion exchange capacities

Question 46

Describe how structure affects nutrient uptake

Answer 46

Soil structure is the arrangement of soil particles into aggregates. Soil structures that create large pores will increase the potential for nutrient leaching. Lack of structure can lead to increases in runoff and erosion.

Question 47

Describe how drainage/aeration affect nutrient uptake

Answer 47

Iron and manganese solubility increases in flooded soils (anaerobic = no oxygen). Nitrate is lost from anaerobic soils by dentrification. Nutrient losses are associated with excessive drainage.

Question 48

Describe how moisture affects nutrient uptake

Answer 48

Adequate soil moisture is especially important for nutrients that move to roots by diffusion (e.g. P). Adequate soil moisture favors decomposition and release N, P, and S from the material undergoing decomposition. As soil moisture decreases, insoluble compounds containing nutrients can form.

Question 49

Describe how pH affects nutrient uptake

Answer 49

Soil pH affects the availability of most nutrients due to physical (leaching, volatilization), chemical (adsorption, desorption, precipitation) and biological processes (mineralization, immobilization) that change with pH. Extremes in soil pH can alter absorption of nutrients by roots by changing root metabolism,

Question 50

Describe how temperature affects nutrient uptake

Answer 50

Temperature can be through plant metabolism where a minimum, optimum, and maximum temperature for nutrient uptake exists and can change with plant growth and development. If the nutrient source is a decomposing organic material, then temperature also can affect the rate of that process.