Section 2 - Essential Plant Nutrients

Question 1

List three ways to make Se fertilization acceptable.

Answer 1

1. Se topdressing is not applied
2. High Se levels in edible animal tissue are prevented
3. Protection against Se deficiency is provided for at least one grazing season following application during the dormant season

Question 2

S is absorbed by plant roots almost exclusively as ___.

Answer 2

sulfate (SO₄^‐2)

Question 3

Name four ways Mg is found in soil solution.

Answer 3

1. lost in percolating water
2. absorbed by microorganisms
3. adsorbed on the CEC
4. reprecipitated as a secondary mineral

Question 4

P tends to stay where it’s applied and not move through the soil, unlike N and K which can be lost from the soil solution. P will accumulate thus N-P-K fertilizer ratios need to be adjusted to P=0.

Answer 4

True

Question 5

Rates of reaction with P are ___ therefore plants have a chance to take it up

Answer 5

slow

Question 6

As organic P is mineralized to inorganic P or as P is added to soil, inorganic P in solution (H₂PO₄^‐/HPO₄^‐2) not absorbed by roots or immobilized by microorganisms can be adsorbed to mineral surfaces or precipitated as secondary P compounds

Answer 6

True

Question 7

The concentration of the inorganic P in the soil solution is the most important single factor governing the availability of plants. Uptake of H₂PO₄^- is more rapid than HPO₄^-2 with the former being most abundant at pH < 7.2.

Answer 7

True

Question 8

Name 7 factors that affect P mineralization and immobilization

Answer 8

1. Microbial activity
2. Residues C/P ratio
3. Soil temperature
4. Soil aeration
5. Soil pH
6. Soil moisture
7. P fertilization

Question 9

What are the 5 available soil solutions for K Loss?

Answer 9

1) Adsorption
2) Leaching
3) Plant removal
4) Erosion
5) Fixation

Question 10

P concentrations in plants range between 0.1 and 0.5%, considerably ___ than N and K. Plants absorb either H2PO4‐ or HPO4‐2 (orthophosphate) depending on soil pH.

Answer 10

lower

Question 11

Organic P represents about __% of total soil P and typically varies between 15 and 80%.

Answer 11

50

Question 12

Solution K⁺ in ___‐textured soils may be much lower than in ___‐textured soils at any given level of exchangeable K.

Answer 12

fine

course

Question 13

Soil moisture: Mo deficiency is accentuated under ___ ___.

Answer 13

dry conditions

Question 14

K is absorbed by plant roots as __ and tissue concentration ranges from _ to _% in dry matter.

Answer 14

K+

1 to 5%

Question 15

___ soils need to be limed first before adding K

Answer 15

Acidic

Question 16

The soil pH of maximum availability for P is pH _._.

Answer 16

6.5

Question 17

Soils containing ___, ___, or ___ have more K than soils containing mainly kaolinitic clays, common in highly weathered soils.

Answer 17

vermiculite, montmorillonite, or mica

Question 18

Excessive Water and Poor Aeration: Any compact, fine-textured, calcareous soil can be Fe ___.

Answer 18

deficient

Question 19

Excessive Water and Poor Aeration: Waterlogged soils exhibit ___ O₂ and lower redox potential, which increases soluble Mn⁺². Mn availability can be ___ by poor aeration in compact soils and by local accumulation of CO₂ around roots and other soil microsites.

Answer 19

reduced

increased

Question 20

___ is a major component of bones and teeth and is important for lactating animals.

Answer 20

P

Question 21

The addition of residues low in P may ____ immobilization if there is not enough P to degrade residues.

Answer 21

stimulate

Question 22

Typical K deficiency symptoms in alfalfa consist of ___ ___ on the leaf edges, whereas ___ and ___ of the leaf edges are observed with corn and other grasses.

Answer 22

white spots

chlorosis and necrosis

Question 23

Organic Cu: Most of the soluble Cu⁺² in surface soils is ___ ___ and is more strongly bound to OM than any other micronutrient.

Answer 23

organically complexed

Question 24

S in Earth’s crust averages ≈ _.__%, comparable to P.

Answer 24

0.05

Question 25

K in primary mineral structure is ___

Answer 25

unavailable

Question 26

Soils do have a lot of P (top 50 cm) but are mostly unavailable due to ___

Answer 26

fixation

Question 27

The extent ___ _ fixation depends on many factors, most importantly on soil minerals.

Answer 27

inorganic K

Question 28

What are eight factors influencing inorganic P fixation in soils?

Answer 28

1. Soil minerals
2. Soil pH
3. Cation and anion effects (NH₄⁺/NO₃^-)
4. Soil OM
5. Time and temperature
6. Soil moisture
7. Fertilizer P management
8. Considerations (rate, time, type, method)

Question 29

What are the six most important factors in determining Ca⁺² availability to plants?

Answer 29

1. Total Ca supply
2. Soil pH
3. CEC
4. % Ca⁺² saturation on CEC
5. Type of soil clay
6. The ratio of solution Ca⁺² to other cations

Question 30

Exchangeable K is highly correlated to K availability to plants as exchangeable K ___, fertilizer K recommendations ___.

Answer 30

increases

decreases

Question 31

Soil Solution Mn: ___ is the common form in solution; its concentration decreases ___ ___ for each unit increase in pH.

Answer 31

Mn⁺²

one hundredfold

Question 32

Organic wastes are excellent sources of ___-___ P, with manure accounting for __% of organic P applied to cropland

Answer 32

plant-available

98

Question 33

Surface adsorption and precipitation reactions are collectively called ___ ___ or retention

Answer 33

P fixation

Question 34

Name eight nutrients that are immobile in plants. Deficiency symptoms show up on ___ leaves first

Answer 34

1. Ca
2. Cu
3. Mn
4. Zn
5. Fe
6. Mo
7. B
8. S

younger

Question 35

Sulfur is essential for ___

Answer 35

protein

Question 36

Which of the following is not true about liming acid soils by applying CaCO3?
A) It supplies Ca to plants
B) It corrects soil acidity
C) It increases crop yield
D) It increases acidic cations saturation of soil colloids

Answer 36

D) It increases acidic cations saturation of soil colloids

Question 37

What are the three Secondary Macronutrients?

Answer 37

1. S
2. Ca
3. Mg

Question 38

K is important for many crop quality characteristics due to its involvement in the ___ and ___ of ___ to plant reproductive and storage organs and subsequent conversion into carbohydrates, proteins, oils, and other products.

Answer 38

synthesis and transport of photosynthates

Question 39

Soil Texture: Coarse-textured, well-drained soils are ___ in B, and crops with a ___ requirement respond to B applications. Sandy soils ___ respond in the same manner.

Answer 39

low

high

don’t

Question 40

The quantity of K transported to the root surface by ___ and ___ ___ is related to K intensity.

Answer 40

diffusion and mass flow

Question 41

Adequate ___ increases straw strength in cereals and increases N₂‐fixation capacity of legumes.

Answer 41

P

Question 42

Texture: The potential for Cu deficiency is high in ___ leached, ___-textured soils.

Answer 42

excessively

course

Question 43

Which of the following does not affect Fe availability in soil solution?
A) crop removal
B) soil organic matter
C) soil pH
D) soil N₂ gas

Answer 43

D) soil N₂ gas

Question 44

Co in Soils: Average total Co concentration in Earth’s crust is ≈ __ ppm. Co in soils typically range from 1 to 70 ppm and average about 8 ppm.

Answer 44

40

Question 45

Cu Deficiency and Toxicity: Although not as common as with other micronutrients, Cu deficiencies do occur in sensitive crops on low Cu soils. Cu toxicity symptoms include reduced ___ ___, poorly developed and discolored root systems, and ___ ___.

Answer 45

shoot vigor

leaf chlorosis

Question 46

Soil S is present in organic and inorganic forms, although ≈ ___% of total S in noncalcareous surface soils exists as ___ __.

Answer 46

90%

organic S

Question 47

Soil texture: In sandy, low OM soils, MoO₄^-2 retention is ___.

Answer 47

low

Question 48

Mineral Mo: The average Mo concentration in the earth’s crust is __ ppm, and typically ranges from 0.2 to 5 ppm in soils. Soil minerals controlling solution MoO₄^-2 concentration are PbMoO₄ and CaMoO₄. CaMoO₄ predominates in both acidic and calcareous soils.

Answer 48

62

Question 49

The percentage of P₂O₅ in Ca₃(PO₄)₂ is: (use Ca=40, P=31, and O=16 g molecular weights)
A) 20
B) Impossible to calculate since there is no P2O5 in the formula.
C) 23
D) 46

Answer 49

D) 46

Question 50

Soil OM: Although lime-induced Fe deficiency occurs in ___ soils, low-OM ___ soils are often in plant-available Fe.

Answer 50

wet

calcareous

Question 51

Mg constitutes ~_% of Earth’s crust; however, total soil Mg content ranges from 0.1% in coarse, humid-region soils to 4% in fine-textured, arid, or semiarid soils formed from high-Mg minerals.

Answer 51

2%

Question 52

K is essential for photosynthesis for the production and activity of specific ___ ___.

Answer 52

photosynthetic enzymes

Question 53

Na in Plants: Na is essential for ___ plants that accumulate salts in vacuoles to maintain turgor and growth. Na⁺ concentration in ___ ___ varies from 0.01 to 10%. Many C4 plants require Na, which is specifically involved in water relations. Many C4 plants occur naturally in arid, semiarid, and tropical conditions.

Answer 53

halophytic

leaf tissue

Question 54

Name five porphyrin molecules Fe is used for in structural components.

Answer 54

1. cytochromes
2. hemes
3. hematin
4. Ferrichrome
5. leghemoglobin

Question 55

The greatest world P resources are in ___ & ___.

Answer 55

Morocco & Western Sahara

Question 56

A soil contains 2% OM with a 2% loss each year (SOM 58:5 C:N). The farmer wanted to increase OM to 3%. How many years will it take if she produces 10,000 lb crop residue/a (residue contains 44% C and 1% N and 70% of the residue is lost by oxidation /a/year). (Hint see page 144 Estimating Soil OM Production and SOM = 58% C, 5% N.)

Question 57

___ P: Available/exchangeable

Answer 57

Labile

Question 58

Co is essential for the growth of some ___ ___. Plant concentration ranges from ___ to ___ ppm.

Answer 58

symbiotic microorganisms

0.02 to 0.5

Question 59

___ ___ generally contains low Mg, although, at rates applied to meet N or other macronutrient needs, sufficient Mg to meet most crop needs can be applied.

Answer 59

Organic biosolids

Question 60

Cl^- is absorbed by plants through ___ and ___ . Active transport of Cl^- across ___ ___ occurs through other anion transporters.

Answer 60

roots and leaves

plasma membranes

Question 61

Soil OM: ___ forms stable complexes with high molecular-weight organic compounds (i.e., lignin, humic, and fulvic acids) that exist as soluble or insoluble complexes.

Answer 61

Zn⁺²

Question 62

Soil solution Cu and plant available Cu are governed predominantly by solution pH and Cu adsorbed on clay and OM surfaces. Primary and secondary minerals dissolve to initially supply solution Cu, which is then adsorbed, incorporated into microorganisms, and complexed by soluble organic compounds.

Answer 62

True

Question 63

Most of the K used for fertilizer comes from:
A) mining K rich ores
B) natural gas
C) Western Sahara (Morocco)
D) particulate deposits

Answer 63

A) mining K rich ores

Question 64

A significant “pool” of organically complexed Cu in equilibrium with solution Cu contributes to ___ ___ to plant roots.

Answer 64

Cu⁺² diffusion

Question 65

Interactions with Other Nutrients: ___ ___ can interact with Fe to induce Fe deficiency. (high Cu, Mn, P, induce low Fe)

Answer 65

Metal cations

Question 66

Name four ways P ions are removed from the soil solution.

Answer 66

1) Precipitation reactions
2) Anion exchange reactions (outer sphere) – will be plant available
3) Reactions with Al or Fe oxide surfaces (inner-sphere) – fixation has taken place
4) Bond strength Ion

Question 67

Ni is the latest nutrient to be established (in ____) as an essential nutrient to higher plants since the recognition of Cl- in 1954.

Answer 67

1987

Question 68

Mainland ___ consumes the most P worldwide as of 2021

Answer 68

China

Question 69

Organic Fe: Most animal wastes contain small quantities of ___-___ Fe. The major benefit of an organic waste application is increased OM and associated ___ effects.

Answer 69

plant-available

chelation

Question 70

Plants take up P in the form of ___ & ___, sometimes as Soil organic phosphate as well. Mostly dependent upon pH of the soil will determine how P will be taken up.

Answer 70

H₂PO₄^‐ (Low pH)
HPO₄^‐2(High pH)

Question 71

Solution P is governed by the solubility of P minerals in the soil (Fig. 5.12). In acid soils Al and Fe phosphate minerals control solution P, while in neutral and calcareous soils Ca phosphate minerals are important. Availability of soluble phosphates is reduced by precipitation of insoluble Fe/Al or Ca phosphates.

Answer 71

True

Question 72

Another K deficiency symptom is the ___ of stalks or stems, which causes ___ in small grains and stalk ___ in corn and sorghum.

Answer 72

weakening

lodging

breakage

Question 73

P solution ___ in the presence of Fe, Al, Ca, K binding with P.

Answer 73

decreases

Question 74

Mineral Zn content of the lithosphere is ≈ __ ppm, and Zn in soil ranges from 10 to 300 ppm (50 ppm average).

Answer 74

70

Question 75

List five forms of Se present in soils.

Answer 75

1. Selenides
2. Elemental Se
3. Selenites
4. Selenates
5. Organic Se

Question 76

Inorganic Cu: The most common source is CuSO₄. CuSO₄ is soluble in water and is compatible with most fertilizers. Soil and foliar applications are both effective, but soil applications are more common. Effectiveness is increased by thoroughly mixing Cu fertilizers into the root zone or by banding near the seed row.

Answer 76

True

Question 77

If a plant residue contains 5000 kg N and 10 kg P, how many grams of H₂PO₄^- do you need to add to your soil to avoid net immobilization of P? (Hint: Assume C/P = 250 is taken as no net mineralization or immobilization)

Answer 77

5000 kg N/(10+X) kg P = 250

5000 = (250) (10+X)

5000 = 2500 + 250X

2500 = 250X

⸫ X = 10 kg P x (97/31) = 31.29

Question 78

Organic Zn: Most animal wastes contain small quantities of plant-available Zn, especially ranging from ___% to ___%. With large manure-application rates, sufficient plant-available Zn can be provided.

Answer 78

0.01% to 0.05%

Question 79

___ ___ is suspended phosphorus attached to particles that are filterable. A portion of this particulate P is also reactive orthophosphate and is typically analyzed along with the soluble orthophosphate.

Answer 79

Particulate phosphorus

Question 80

The extent of inorganic ___ ___ depends on many factors, most importantly on soil pH

Answer 80

P fixation

Question 81

Ni-deficient plants accumulate toxic levels of ___ in leaf tips because of reduced urease activity.

Answer 81

urea

Question 82

Plant available Fe is governed primarily through ___ and ___ fractions in soils.

Answer 82

mineral and organic

Question 83

S ___ is the conversion of organic S to inorganic SO₄^-2

Answer 83

mineralization

Question 84

Ni has been demonstrated as essential to ___-___ crops.

Answer 84

small-grain

Question 85

Plants absorb Ca⁺² from the ___ ___, where mass flow and root interception are the primary mechanisms of Ca transport to the ___ ___.

Answer 85

soil solution

root surface

Question 86

Soil pH: Solution Cu ___ with ___ pH due to decreased mineral solubility and increased adsorption.

Answer 86

decreases with increasing

Question 87

Soil Solution Cu: Solution Cu concentration is usually low, ranging between ___ and ___ M.

Answer 87

10^-6 and 10^-8

Question 88

Soil Solution Zn⁺² is ___ (2-70 ppb), with more than half complexed by OM. Above pH 7.7, ZnOH⁺ becomes the most abundant species.

Answer 88

low

Question 89

Exchangeable K on soil colloids is ___ ___.

Answer 89

readily available

Question 90

P is active and mostly reactive that _______ to form compounds

Answer 90

phosphorylates

Question 91

Soil solution K⁺ concentration optimum plant growth ranges from _ to __ ppm, depending on crop yield level.

Answer 91

1 to 10

Question 92

___ Ca can also be foliar applied to crops.

Answer 92

Chelated

Question 93

What are the three abundant minerals that are not mineral?

Answer 93

1. C
2. O
3. H

Question 94

Excess Mg occurs in soils formed from ___ ___ or influenced by ___ high in Mg.

Answer 94

serpentine minerals

groundwaters

Question 95

Because of the mobility of plant Mg⁺² and its ready translocation from ___ to ___ plant parts, deficiency symptoms often appear first on ___ leaves.

Answer 95

older to younger

lower

Question 96

___ ___ ___(DIP): P desorbed from oxides or secondary minerals.

Answer 96

Dissolved inorganic P

Question 97

K is essential for photosynthesis ___ ___ through leaf stomata

Answer 97

CO₂ absorption

Question 98

K is part of many plant cell components such as proteins and chlorophyll.

Answer 98

False

Question 99

K deficiency symptom for corn leaf is identical to N. The chlorosis that appears on older leaves makes it impossible to differentiate.

Answer 99

False

Question 100

Adsorbed Cu: ___ is chemically adsorbed to surfaces of clays; OM; and Fe, Al, or Mn oxides.

Answer 100

Cu⁺²

Question 101

Solute Concentration in ___: For plants to absorb and use nutrients efficiently, nutrients accumulate in ___ until transported to growing plant organs.

Answer 101

Vacuoles

vacuoles

Question 102

P content in biosolids ranges from 2 to 7%, with most present as ___ ___.

Answer 102

inorganic P

Question 103

K in solution is ___

Answer 103

available

Question 104

The eutrophication blamed on P in water bodies is highly exaggerated and scientifically false. Nitrogen is the cause of it all.

Answer 104

False

Question 105

K is added to the soil solution by the ___ of ___ and cation exchange reactions as K⁺.

Answer 105

dissolution of minerals

Question 106

Soil B exists in ___, adsorbed on ___ and Fe/Al ___ surfaces, combined with OM, and in soil solution.

Answer 106

minerals

clay

oxide

Question 107

Organic B: B content in animal fertilizers ___ and may not provide ___ plant-available B to plants.

Answer 107

varies

sufficient

Question 108

___ ___ is an important fraction is highly weathered, humid region soils containing large amounts of Al/Fe oxides.

Answer 108

Adsorbed SO₄^-2

Question 109

The two dominant P species at normal soil pH are:
A) H₂PO₄^-1 and PO₄^-3
B) H₃PO₄ and HPO4^-2
C) H₂PO₄^-1 and H₂PO₄^-2
D) H₃PO₄ and H₂PO₄^-1

Answer 109

C) H₂PO₄^-1 and H₂PO₄^-2

Question 110

Name four nutrients in the soil that are immobile.

Answer 110

1. P
2. Fe⁺²
3. Zn⁺²
4. Mo

Question 111

P mineralization from organic matter - (4‐10 lb/a/y) mineralized and plants need 10‐40 lb/a)

Answer 111

True

Question 112

What are two methods of producing elemental Sulfur?

Answer 112

1. By-byproduct from H₂S gas
2. By traditional mining

Question 113

Name three plant benefits Co has for plants.

Answer 113

(1) acid, highly leached, sandy soils with low total Co
(2) highly calcareous soils
(3) some peaty soils

Question 114

Plants absorb Mn⁺² and ___ molecular weight organically complexed Mn.

Answer 114

low

Question 115

Name 4 ways the soil solution is replenished?

Answer 115

1. Dissolution
2. Cation/Anion Exchange
3. Desorption
4. Organic Mineralization

Question 116

___ leaf color is also associated with P deficiency

Answer 116

Purple

Question 117

___, ___, ___, ___, ___ are the P forms in soil solution.

Answer 117

Adsorption, Absorption, Precipitation, Dissolution, Sorption

Question 118

Name six symptoms Zn deficiencies that are widespread throughout the world and are identified.

Answer 118

1. light green, yellow, or white areas between leaf veins
2. eventual tissue necrosis in chlorotic leaf areas
3. shortening of stem or stalk internodes
4. small, narrow, thickened leaves
5. premature foliage loss
6. malformation of fruit, often with little or no yield

Question 119

Diammonium phosphate (DAP) is produced by reacting 2 moles ___ with 1 mole of ___ ___.

Answer 119

ammonia

phosphoric acid

Question 120

B is one of the ___ widely applied micronutrients.

Answer 120

most

Question 121

K is essential for photosynthesis for the maintenance of electroneutrality during ___ in ___.

Answer 121

photophosphorylation in chloroplasts

Question 122

In addition to most inorganic Mg salts, other materials containing synthetic Mg chelates (2-4% Mg) and natural organic complexing substances (4-9%) are suited for application as foliar sprays.

Answer 122

True

Question 123

Buffer capacity is the resistance to change, therefore Soil P in solution is buffered as well. These are all ___-___

Answer 123

pH-dependent

Question 124

P fertilizer may be ___ on the soil surface (liquid or dry) or it can be placed in a ___ ___.

Answer 124

broadcast

concentrated band

Question 125

Name 4 ways P mineralization occurs.

Answer 125

1) Conversion of organic P to inorganic P
2) Organic P -> H₂PO₄^-
3) Precipitation
4) Adsorption

Question 126

As a primary constituent of ___, Mg⁺² is essential for ___.

Answer 126

chlorophyll

photosynthesis

Question 127

If a soil has 2% OM content and mineralization rate is 1%, calculate the quantity of P mineralized (lb P/afs). Assume humus (OM) contains 58%C, 5% N and 0.5% P; C:N:P = 100:10:1

Answer 127

• OM is about 5% N, 0.5% P and only 1% OM is mineralized.
• Total OM in an acre = 2x10⁶ x 0.02 = 40,000 lb OM
• Total OM 1% mineralized 40,000 x 0.01 = 400 lb OM
• 5% of mineralized OM is N = 400 x 0.05 = 20 lb N/a
• 0.5% of mineralized OM is P = 400 x 0.005 = 2.0 lb P/a

Question 128

Name five chemical inorganic sources of Cl.

Answer 128

1. Ammonium chloride (NH₄Cl)
2. Calcium chloride (CaCl₂)
3. Magnesium chloride (MgCl₂)
4. Potassium chloride (KCl)
5. Sodium chloride (NaCl)

Question 129

Soil OM: Unavailable chelated Mn⁺² compounds form, causing low Mn⁺² availability in high-OM ___ and ___ soils.

Answer 129

peats and muck

Question 130

Se in Plants: Se is not essential for plants, but it is required by animals. Plant species differ in Se uptake.

Answer 130

True

Question 131

___ in crops grown on coarse-textured soils are generally more susceptible to S deficiency because these soils often have low OM contents.

Answer 131

Immobilization

Question 132

Animal and municipal wastes contain ~_-_% Ca by dry weight and are excellent Ca sources.

Answer 132

2-5%

Question 133

P at High pH – fixation mostly as ___ ___

Answer 133

calcium phosphates

Question 134

Too much P is not good due to environmental impacts such as ___ from surface water runoff

Answer 134

eutrophication

Question 135

___ (S₂O₃^‐2), which can also be absorbed by plants, requires less energy by the plant in ___ to S^‐2 and cysteine.

Answer 135

Thiosulfate

conversion

Question 136

Organic P exists as inositol P, phospholipids, nucleic acids, and other compounds.

Answer 136

True

Question 137

Mg is required for the maximum activity of almost every ___ ___ involved in carbohydrate metabolism.

Answer 137

phosphorylating enzyme

Question 138

In Mg-deficient acid soils, ___ ___ applications are recommended to increase soil pH and Mg availability.

Answer 138

dolomitic lime

Question 139

P at low pH fixation is mainly by hydrous oxides of ___, ___, ___ and some chemical fixation by soluble ___, ___, ___.

Answer 139

Fe, Mn, Al
Fe, Mn, Al

Question 140

Under ___ soil moisture or in compacted soils, root growth is restricted, O₂ supply is reduced, and K absorption is ___.

Answer 140

high

slowed

Question 141

Calculate the percent of N, P and K, and N-P-K (=N-P₂O₅-K₂O) in the following fertilizer materials: NH₄NO₃, KCl, NH₄H₂PO₄, (NH₄)₂HPO₄, and CO(NH₂)₂ (Molecular weights, H = 1, K= 39, C = 12, N = 14, O = 16, P = 31, S = 32, Cl = 35.5, P = 39)

Answer 141

NH4NO3

%N = 28/80 x 100 = 35%

%P = 0/80 x 100 = 0%

%K = 0/80 x 100 = 0%

N-P-K = 35-0-0

KCl

%N = 0/74.5 x 100 = 0%

%P = 0/74.5 x 100 = 0%

%K = 39/74.5 x 100 = 52.35%

K = %K x 1.2 = 52.35 x 1.2 = 63

N-P-K = 0-0-63

NH4H2PO4

%N = 14/115 x 100 = 12.17%

%P = 31/115 x 100 = 26.96%

%K = 0/115 x 100 = 0%

P = %P x 2.29 = 26.96 x 2.29 = 62

N-P-K = 12-62-0

(NH4)2HPO4

%N = 14/132 x 100 = 10.61%

%P = 31/132 x 100 = 23.48%

%K = 0/132 x 100 = 0%

P = %P x 2.29 = 23.48 x 2.29 = 54

N-P-K = 11-54-0

CO(NH2)2

%N = 28/60 x 100 = 46.67%

%P = 0/60 x 100 = 0%

%K = 0/60 x 100 = 0%

N-P-K = 47-0-0

Question 142

Plant Factors: Plant species and varieties differ in their susceptibility to Zn deficiency. ___, ___, and ___ ___ are susceptible to low Zn.

Answer 142

Corn, beans, and fruit trees

Question 143

Soil Solution B: H₃BO₃0 I the predominant solution species over _-_ pH. B is transported in the soil solution to absorb plant roots by both ___ and ___ ___.

Answer 143

5-9

diffusion

mass flow

Question 144

Lignin Formation in Cell Walls: Several enzymes important to the synthesis of lignin contain Cu. Cu deficiency results in deformed ___ and ___, increasing the potential for lodging.

Answer 144

leaves and stems

Question 145

P deficiency symptoms can appear in P-sensitive crops emerging under ___, ___ conditions, even in soils with sufficient plant-available P.

Answer 145

cool

wet

Question 146

The common B application methods are ___, ____, or applied as a ___ ___ or ___.

Answer 146

broadcast

banded

foliar spray

dust

Question 147

K is ___ in both soil and plants

Answer 147

mobile

Question 148

Which of the following K fertilizer contains the highest K₂O%, relatively?
A) K₂SO₄
B) KCl
C) KNO₃
D) K₂CO₃

Answer 148

D) K₂CO₃

Question 149

Muriate of potash is ___ (90% of all fertilizers)

Answer 149

KCl

Question 150

There is no evidence of interactions among the micronutrients and with the secondary or major plant nutrients.

Answer 150

False

Question 151

_ ___ can influence the amount of K leached.

Answer 151

K source

Question 152

A soil has a CEC = 10 meq/100 g with 40 and 2%, Ca and Mg saturation, respectively. Calculate the lbs/a of CaCO₃ and MgSO₄ needed to increase Ca and Mg saturation to 65 and 8%, respectively. (M.W. Ca=40, C=12, O=16, Mg=24, S=32).

Answer 152

Ca_increase = (10 meq/100 g) x (0.25) x (20 mg/meq) = 50 mg/100 g = 0.05 g/100g = 0.05 lb/100 lb = 0.05 lb x 20,000 = 1,000 lb/a

CaCO₃ needed = (1,000 lb/a) x (100/40) = 2,500 lb/a

Mg_increase = (10 meq/100 g) x (0.06) x (12 mg/meq) = 7.2 mg/100 g = 0.0072 g/100g = 0.0072 lb/100 lb = 0.0072 lb x 20,000 = 144 lb/a

MgSO₄ needed = 144 lb x (120/24) = 720 lb/a

Question 153

Cl^- is highly ___ in soils.

Answer 153

soluble

Question 154

Continued ___ increases organic P mineralization decreasing soil organic P.

Answer 154

cultivation

Question 155

Plant available Zn is governed predominantly by Zn mineral solubility, soil OM, and Zn adsorbed on clay and OM surfaces soils. Primary and secondary minerals initially dissolve to provide solution Zn, then adsorbed onto the CEC, incorporated into microbial biomass, or complex by organic compounds in solution. Like Fe, chelated Zn is essential to the transport of Zn to root surfaces for uptake.

Answer 155

True

Question 156

%P₂O₅ = _.__ x %P

%K₂O = _.__ x %K

Answer 156

%P₂O₅ = 2.27 x %P

%K₂O = 1.20 x %K

Question 157

Name six nutrients that are mobile in plants. Deficiency symptoms show up on ___ leaves first.

Answer 157

1. N
2. P
3. K
4. Mg
5. Cl
6. S

older

Question 158

Earth’s crust contains ≈ _._% total Ca.

Answer 158

3.5

Question 159

The ___ the proportion of high K minerals, the greater the potential K availability.

Answer 159

greater

Question 160

O₂ and Photosynthesis: Most O₂ in the atmosphere originates from ___-___ electrons in photosynthesis.

Answer 160

Mn-facilitated

Question 161

___ Ca⁺² uptake combined with ___ translocation of carbohydrates causes distinct symptoms in fruits and vegetable crops.

Answer 161

Low

limited

Question 162

Name two problems of excess Cl^- occur in some irrigated areas.

Answer 162

1. High Cl^- in the irrigation water
2. Insufficient water to leach accumulated Cl

Question 163

____ of the Cl^- uptake by high concentrations of NO₃^- and SO₄^-2 has been observed in many plants. The effect of Cl fertilization on ___ and ___ disease suppression has been observed on a few crops.

Answer 163

Depression

root and leaf

Question 164

Cl Functions: Cl^- is involved in ___ and ___ charge balance, which are important to biochemical processes.

Answer 164

osmotic and ion

Question 165

What are the three fertilizer materials Ca is found in?

Answer 165

1. triple superphosphate (12-14% Ca)
2. calcium nitrate (19% Ca)
3. lime-ammonium nitrate (10% Ca)

Question 166

The concentration of P in the soil solution is influenced by the rate and extent of P mineralization/immobilization, adsorption/desorption, and precipitation/dissolution reactions in the soil. Soils high in soluble Fe/Al react with ortho- and polyphosphates to form a variety of insoluble P compounds, depending on pH, which is largely unavailable to plants.

Answer 166

True

Question 167

Low concentrations of V are beneficial for the growth of microorganisms, animals, and higher plants. Although essential for green algae, there is still no decisive evidence that V is necessary for higher plants. V may partially substitute for Mo in N₂ fixation by Rhizobia. It may also function in biological oxidation-reduction reactions. Increases in growth attributable to V have been reported for asparagus, rice, lettuce, barley, and corn. V requirement of plants is 62 ppb, whereas normal V concentration in plants averages approximately 1 ppm.

Answer 167

True

Question 168

Soil solution Mg⁺² concentration typically ranges from _ to __ ppm in temperate region soils.

Answer 168

5 to 50

Question 169

Photosynthesis and Respiration: Photosynthesis (reducing CO₂ to carbohydrates) and respiration (oxidizing carbohydrates to CO₂) involve the transfer of electrons that requires ___.

Answer 169

Cu

Question 170

K is essential for photosynthesis for ___ ___. K provides much of the osmotic “pull” that draws water into plant roots.

Answer 170

water relations

Question 171

What are the 3 main processes for Sulfur mining?

Answer 171

1. Open-pit mining
2. Underground mining
3. Frasch method

Question 172

Inorganic Zn: __ __ is the most common Zn fertilizer source. Inorganic Zn sources are satisfactory fertilizers because they are soluble in soils.

Answer 172

Zinc sulfate

Question 173

K⁺ is absorbed by roots or immobilized by microorganisms or can be adsorbed to mineral surfaces or precipitate as secondary K compounds.

Answer 173

True

Question 174

K is involved in the ___ of ___ important to energy utilization, starch synthesis, N metabolism, and respiration.

Answer 174

activation of enzymes

Question 175

Interaction with Other Nutrients: Other metal cations ___ Zn⁺² uptake. This antagonistic effect is prevalent with Cu⁺² and Fe⁺².

Answer 175

inhibit

Question 176

In ___ pH soils, elevated levels of exchangeable Al⁺³ and Mn⁺² create an unfavorable root environment for nutrient uptake. More K⁺ can be adsorbed to CEC, reducing potential K leaching losses.

Answer 176

low

Question 177

Soil Moisture: B deficiency is often associated with ___ weather, where low soil moisture reduces B release from OM and B uptake through ___ B ___ to absorbing root surfaces.

Answer 177

dry

reduced transport

Question 178

What are the 4 available soil solutions for K Gain?

Answer 178

1. Atmospheric deposition
2. Plant residues & Animal Manures
3. Inorganic fertilizers
4. Slowly available potassium minerals

Question 179

What are the 8 Micronutrients?

Answer 179

1. Mn
2. Mo
3. Cl
4. B
5. Fe
6. Zn
7. Cu
8. Ni

Question 180

Today most P fertilizer production is based on acidification of apatite from ___ ___.

Answer 180

phosphate rock

Question 181

___ P: Fixed/non-exchangeable P

Answer 181

Nonlabile

Question 182

What are the 4 advantages of P banding?

Answer 182

1. Early crop growth enhancement
2. The concentration of P to minimize soil contact and reaction
3. Placement in the root zone
4. Minimize contact with Fe, Al, Ca, K which can precipitate

Question 183

Primary K Minerals come from ___ and ___.

Answer 183

Feldspars and Mica

Question 184

P manure is highly variable nutrient content and ranges between:

N = XX - XX%

P = XX-XX%

K > XX%

Answer 184

N = 25-90%

P = 50-100%

K > 85%

Question 185

The primary Ca sources are liming materials such as CaCO₃, CaMg(CO₃)₂, and others applied to neutralize soil acidity.

Answer 185

True

Question 186

Name five free nutrients in the soil that are mobile.

Answer 186

1. NO₃^-
2. SO₄^-2
3. Ca⁺²
4. Mg⁺²
5. K⁺

Question 187

P immobilization when C/P ratio > XXX:1 (P < 0.2%)

Answer 187

300

Question 188

Organic Cl: Because of the solubility and mobility of Cl^-, most animal and municipal wastes are ___ in Cl^-.

Answer 188

low

Question 189

What are the three Primary Macronutrients?

Answer 189

1. N
2. P
3. K

Question 190

B fertilization rates depend on plant species, soil cultural practices, rainfall, liming, soil OM, and other factors.

Answer 190

True

Question 191

Name five ways the soil solution nutrients are reduced.

Answer 191

1. Precipitation
2. Adsorption
3. Absorption
4. Sorption
5. Immobilization

Question 192

Interactions with Other Nutrients: High Zn, Fe, and P concentrations in soil solution can ___ Cu adsorption by roots and ___ Cu deficiency.

Answer 192

depress

intensify

Question 193

Ca, Mg, and S are primary essential macronutrients, and they are all catalysts in plant metabolism.

Answer 193

False

Question 194

List four items that Zn rates depend on.

Answer 194

1. the crop
2. Zn source
3. method of application
4. the severity of Zn deficiency

Question 195

____________is the transfer of energy‐rich H₂PO₄^‐ molecules from ATP to energy‐requiring substances in the plant

Answer 195

Phosphorylation

Question 196

___ P: P left in the soil after fertilization

Answer 196

Residual

Question 197

Mn and Lignin Synthesis: Like Cu, Mn activates several ___ that synthesize several amino acids and phenols important to ___ production.

Answer 197

enzymes

lignin

Question 198

Although it has been suggested that plants also absorb soluble, low-molecular-weight organic P compounds (i.e., nucleic acid and phytin), these P compounds are likely converted to H₂PO₄^‐ in the ___.

Answer 198

rhizosphere

Question 199

___ ___ ___ (DRP) is a measure of the dissolved (soluble) phosphorus compounds that are readily available for use by plants and algae. Dissolved reactive phosphorus concentrations are an indication of a waterbody’s ability to support nuisance algal or plant growths (algal blooms).

Answer 199

Dissolved reactive phosphorus

Question 200

P supply to plant roots is greatly enhanced by a ___ relationship between plant roots and fungal microorganisms called ___.

Answer 200

symbiotic

mycorrhizae

Question 201

Mg in clay minerals is ___ ___ by leaching and exhaustive cropping.

Answer 201

slowly depleted

Question 202

Occluded and Coprecipitated Cu: A ___ fraction of soil Cu is occluded in various mineral structures, such as clay minerals and Fe, Al, and Mn oxides.

Answer 202

significant

Question 203

Plants contain _-_% Mg⁺²

Answer 203

0.1-0.4%

Question 204

___ ___briefly increases with distance, peaks, and then decreases. pH decreases due to acidic solution.

Answer 204

Extractable P

Question 205

Gains: fertilization, mineralization OM, desorption, particulate deposition, dissolution, weathering

Answer 205

True

Question 206

Si in Plants: Plants absorb Si as silicic acid (H₄SiO₄0). Although no biochemical role for Si in plants has been identified, it has been proposed that enzyme-Si complexes form that act as protectors or regulators of photosynthesis and enzyme activity. The beneficial effects of Si have been attributed to partial remediation of toxic effects of high soil Mn⁺², Fe⁺², or Al⁺³; plant disease resistance; greater stalk strength and resistance to lodging; increased availability of P; reduced transpiration; and improved drought tolerance.

Answer 206

True

Question 207

____ P: P dissolved in extractants (Mehlich 1 or 3, Bray-P, Olsen, etc. (see Huluka and Evans, 1991)

Answer 207

Extractable

Question 208

Name four ways fertilizers can correct ruminant Co deficiency.

Answer 208

1. adding it to feed, salt licks, or drinking water
2. direct injection
3. using Co bullets (oral tablets)
4. fertilizing forage crops with small amounts of C

Question 209

Ca⁺² is essential for ___ ___ and ___; therefore, deficiency symptoms are primarily exhibited in ___ ___ of rapid cell division.

Answer 209

cell division and elongation

meristematic regions

Question 210

The main forms of Mo in soil include primary and secondary minerals, exchangeable Mo held by Fe/Al oxides, Mo in soil solution, and organically bound Mo. Although Mo is an anion in solution, the relationships between these forms are like those of other metal cations.

Answer 210

True

Question 211

___ ___ occurs when the potassium content of plants surpasses what is required for optimal growth.

Answer 211

Luxury consumption

Question 212

Two soils have a CEC = 5 meq/100 g and a 25 meq/100 g. Calculate the exchangeable K content for both soils in lb/a.

Answer 212

Soil A (lb/a) = (5 meq/100 g) x (39 mg/meq) = 195 mg/100 g = 0.195g/100g

= 0.195 lb x 20,000 = 3,900 lb K/a

Soil B (lb/a) = (25 meq/100 g) x (39 mg/meq) = 975 mg/100 g = 0.975g/100g

= 0.975 lb x 20,000 = 19,500 lb K/a

Question 213

K is essential for photosynthesis for ___ of ___. Once CO₂ is assimilated into sugars during photosynthesis, they are transported from leaves to fruits, roots, tubers, and grains where they are stored or used for growth.

Answer 213

translocation of assimilates

Question 214

Excessive amounts of Mo are ___, especially to grazing animals. High-Mo ___ may occur in wet, high-pH, and high OM soils.

Answer 214

toxic

forage

Question 215

Calcium, magnesium, and sulfur are taken up by plants as Ca^-2, Mg^-2, and SO₄⁺², respectively.

Answer 215

False

Question 216

Organically Complexed B: OM represents a ___ potential source of plant-available B in soils, which ___ with increasing OM.

Answer 216

large

increases

Question 217

Organic S: There is a close relationship between organic C, total N, and total S n soils. The C:N:S ratio in most well-drained, noncalcareous soils is about ___.

Answer 217

120:10:1.4

Question 218

Plant roots absorb ___, which is involved in many enzymatic activities.

Answer 218

Zn⁺²

Question 219

___‐___ fertilizer or ___ P applied to soil increases P in soil solution

Answer 219

Water-soluble
biosolid

Question 220

S cycle, forms, gains, and losses in soil are similar to which of the following essential nutrient comparatively?
A) N
B) K
C) Mg
D) P

Answer 220

A) N

Question 221

Cell Turgor: For rapid gas exchange by leaves during active photosynthesis, the epidural guard cells of stomates are turgid, caused by ___ ___ from neighboring cells.

Answer 221

K⁺ pumped

Question 222

Soil pH: MoO₄^-2 availability, unlike that of other micro-nutrients increases approximately ___ per unit increase in soil pH.

Answer 222

tenfold

Question 223

Plant essential micronutrients are needed in such very small amounts and thus they do not cause any chlorosis when deficient and no toxicity when too much in soil.

Answer 223

False

Question 224

Inorganic Mn: Manganese sulfate is the most common Mn source and is soil or foliar applied. Natural organic complexes and chelated Mn are also available and are usually foliar applied. Broadcast application of Mn chelates, and natural organic complexes is not normally advised because soil Ca or Fe can replace Mn in these chelates, and the freed Mn is usually converted to unavailable forms. Also, more available chelated Ca or Fe enhance Mn deficiency.

Answer 224

True

Question 225

B is ___ needed by animals, fungi, or microorganisms. Its primary function is in the plant ___ ___ ___.

Answer 225

not

cell wall structure

Question 226

___ ___ represents the entrapment of K⁺ between the layers of 2:1 clays, predominantly ___ ___.

Answer 226

K fixation

hydrous mica

Question 227

Chelate Dynamics: Numerous soluble organic compounds in the soil can complex, or chelate, ___, and other micronutrients.

Answer 227

Fe⁺³

Question 228

Name three sources of Na-containing fertilizers.

Answer 228

1. K fertilizers with NaCl impurities
2. NaNO₃ (~25% Na)
3. Multiple nutrient fertilizers with Na

Question 229

Mn Deficiency and Toxicity: Because of its essential role in photosynthesis, root and shoot growth rates are reduced in Mn deficient plants. As a result, N and P accumulate, which increases the potential for root and leaf diseases. Mn is immobile in the plant, so ___ leaves initially exhibit deficiency symptoms.

Answer 229

younger

Question 230

Cl concentration is ___% to ___% in Earth’s crust and occurs primarily in igneous and metamorphic rocks.

Answer 230

0.02% to 0.05%

Question 231

Ca deficiency is uncommon but can occur in highly ___, ___ acid soils.

Answer 231

leached, un-limed

Question 232

Soil contains 2% soil organic matter (SOM) with an annual decomposition rate of 1%. Calculate the amount of N and P mineralized (lb/afs) from SOM (Assume humus SOM = 58% C, 5% N and 0.5% P)?

Answer 232

Total OM in an acre = 2x10⁶ x 0.02 = 40,000 lb OM

Total OM 1% mineralized = 40,000 x 0.01 = 400 lb OM

N mineralized = 400 lb OM x 0.05 = 20 lb N/afs

P mineralized = 400 lb OM x 0.005 = 2.0 lb P/afs

Question 233

Reduced Inorganic S (S^-2 and S^o): Sulfides do not exist in well-aerated soils. In normal submerged soils well supplied with Fe, the H₂S liberated from OM is almost completely removed from the solution by reaction with Fe⁺² to form FeS, which undergoes conversion to pyrite (FeS₂).

Answer 233

True

Question 234

Soil OM: Higher B availability in ___ soils compared with subsurface soils is related to increased soil OM.

Answer 234

surface

Question 235

The majority of Cl^- in soils originates from ___ trapped in parent material, from marine ___, and from volcanic ___.

Answer 235

salts

aerosols

emissions

Question 236

Organic Mo - Only small quantities of Mo occur in ___ wastes (0.0001–0.0005% Mo), although with most manures, average application rates will provide sufficient plant-available Mo. Mo content in ___ waste is usually low, averaging 0.0001% Mo.

Answer 236

animal

municipal

Question 237

Adequate ___ is associated with increased root growth

Answer 237

P

Question 238

Mg⁺² is absorbed by plants from the ___ ___ and, like Ca⁺², is supplied to plant roots predominantly by ___ ___.

Answer 238

soil solution

mass flow

Question 239

P mobility in soil is ____ or ____

Answer 239

little or none

Question 240

K in organic wastes (manure and sewage sludge) occurs predominantly as ___ ___K⁺.

Answer 240

soluble inorganic

Question 241

Soil Aeration - Normal root function is strongly dependent on an adequate ___ supply.

Answer 241

O₂

Question 242

Interaction with Other Nutrients: ___ levels of Cu, Fe, or Zn can reduce Mn⁺² ___ by plants.

Answer 242

High

uptake

Question 243

The equilibrium among solution, exchangeable, organic, and mineral forms determines Mn availability to plants. The major processes are Mn oxidation-reduction and complexing solution Mn with natural organic chelates. Like Fe, the continuous cycling of OM significantly contributes to soluble Mn. Factors influencing the solubility of soil Mn include pH, redox, and organic complexation. Soil moisture, aeration, and microbial activity influence redox, while complexation is affected by OM and microbial activity.

Answer 243

True

Question 244

Mineral Cu: Cu concentration in Earth’s crust averages about __-__ ppm.

Answer 244

50-70

Question 245

Dissolved P needs to stay below 0.03 mg/L to avoid eutrophication issues (waterway and oceanic).

Answer 245

True

Question 246

The relative mobility of B in plants ___ among species.

Answer 246

varies

Question 247

%K₂O = %K x _.__

Answer 247

1.20

Question 248

Solution Mo: The extremely low concentration of solution Mo is reflected in the low Mo content of ___ material. At solution concentrations 74 ppb, Mo is transported to plant roots by ___ ___, while Mo diffusion to plant roots occurs at levels 64 ppb.

Answer 248

plant

mass flow

Question 249

Name 5 out of 9 P fertilizer sources.

Answer 249

1. Triple super phosphate (TSP) -> 0‐44‐0
2. Diammonium phosphate – DAP ->
3. Monoammonium phosphate – MAP ->
4. Ammonium polyphosphate (APP)
5. Monopotassium phosphate (KH₂PO₄) -> 0‐51‐35
6. Dipotassium phosphate (K₂HPO₄) -> 0‐41‐41
7. Rock phosphate – not a soluble source of P ->
8. Bone Meal – organic, ~ 9% P₂O₅
9. Struvite (and closely related Brushite) – mineral from sewage sludge processing, also has Mg

Question 250

Mineral B: B occurs in low concentrations in Earth’s ___ and in most ___ rocks. Total B in soils varies between __ and __ ppm. The main B mineral in soils is ___, relatively insoluble borosilicate.

Answer 250

crust

igneous

2 and 200

tourmaline

Question 251

Weathering of mica to vermiculite in clay minerals:

• K Content = ~10% Mica, CEC = 0
• K Content = 6-8% & 4-6% Hydrous Mica, CEC = 30-50
• K Content = <1% Vermiculite, CEC = 150

Answer 251

True

Question 252

In cruciferous S-deficiency crops, it may develop as a reddish color on the undersides of the leaves, turning redder as it progresses and resulting in paler-than-normal blossoms and severely impaired seed set.

Answer 252

True

Question 253

The ___ ___ treatment process of bones and P minerals (apatite) was patented in the mid-1800s.

Answer 253

sulfuric acid

Question 254

B-deficiency symptoms vary with crop species but commonly affect both ___ and ___ ___.

Answer 254

root

top growth

Question 255

S cycling in the soil-plant-atmosphere continuum is similar to N since both have ___ components, inorganic and organic. Their occurrence in soils is mainly associated with ___.

Answer 255

gaseous

OM

Question 256

Si in Soils: Si is the second most abundant element in Earth’s crust, averaging ≈ ___Si, while Si content in soils is 5% to 40%.

Answer 256

28%

Question 257

Plant Factors: Although ___ of both Fe⁺³ and Fe⁺² to the root occurs, Fe⁺³ is reduced to Fe⁺² before ___. Some plants exhibit a unique mechanism to tolerate low Fe availability.

Answer 257

diffusion

absorption

Question 258

The most essential function of P in plants is in ____ ____ and transfer ___ and ___.

Answer 258

energy storage
ATP
ADP

Question 259

The quantity of P mineralized in soils ___ with increasing organic P content

Answer 259

increases

Question 260

O₂ and Photosynthesis: ___ is important Mn function in the photosynthetic production of carbohydrates from CO₂ and the evolution of O₂.

Answer 260

Cl^-

Question 261

Plant factors: Crops vary in their sensitivity to ___ solution Mo

Answer 261

low

Question 262

Interactions with Other elements: When ___ availability is high, plants can tolerate ___ B availability. Under ___ Ca supply, many crops exhibit ___ B tolerance.

Answer 262

Ca

higher

low

lower

Question 263

Weather Effects: Under dry soil conditions Mn availability is ___. In saturated soils, soluble Mn⁺² can increase to ___ levels.

Answer 263

reduced

excessive

Question 264

Mo is absorbed as the weak acid ___ that can form complexes with other anions such as phosphomolybdate. Mo ___ may explain why Mo can be absorbed in relatively large amounts without any apparent toxicity. Mo content of plants is normally low (___ - ___ ppm), because of extremely low MoO₄^-2 in solution.

Answer 264

molybdate

complexation

0.2–2

Question 265

___ can block K in the clay interlayers (non-expanding clays).

Answer 265

NH₄

Question 266

Which of the following fertilizer contains the highest percentage of sulfur?
A) K₂SO₄
B) H₂SO₄
C) (NH₄)₂SO₄
D) S

Answer 266

D) S

Question 267

B adsorbed by plants is predominantly undissociated ___ ___. The anion forms exist when soil pH > _.

Answer 267

boric acid

7

Question 268

___ ___ is the most common B source.

Answer 268

Sodium tetraborate

Question 269

_ is the most absorbed by plants except N.

Answer 269

K

Question 270

___ cycling in soils is very similar to that described for Fe and Zn.

Answer 270

Cu

Question 271

Nonexchangeable K in Secondary minerals is ___ ___

Answer 271

slowly available

Question 272

K ___ is a slow process compared with the mass flow and is limited to distances of only 1-4 mm. ___ accounts for approximately __% of K absorption by roots

Answer 272

diffusion

Diffusion

90

Question 273

In most soils, K ___ ___ are small, except in coarse‐textured or organic soils in humid regions or under irrigation.

Answer 273

leaching losses

Question 274

Peak Phosphorus is predicted to occur in 20XX-20XX, non-renewable and finite resource.

Answer 274

2040-2050

Question 275

Organic Cu: Although most animal wastes contain small quantities of plant-available Cu, elevated Cu levels occur in swine manure because of Cu added to the feed. As with Fe and Zn, the primary benefit of an organic waste application is increased OM and associated natural chelation properties that increase Cu availability.

Answer 275

True

Question 276

___ is the process or technique of treating a material with acid. Treating phosphate rock with acid is a good example of ___.

Answer 276

Acidulation

acidulation

Question 277

Continued application of wastes based on crop N requirements will substantially ___ soil P.

Answer 277

increase

Question 278

Good correlations have been obtained relating P taken up by plants and chemical soil tests.

Answer 278

True

Question 279

Ni content of plants normally ranges from 0.1 to 1.0 ppm and is supplied to plants as ___.

Answer 279

Ni⁺²

Question 280

Climatic Conditions: Zn deficiencies are more pronounced during ___, ___ seasons and often disappear during warmer weather.

Answer 280

cool, wet

Question 281

Zn Adsorption: The mechanism of Zn⁺³ adsorption does not occur to any great extent on the ___ compared to Ca⁺² and Mg⁺².

Answer 281

CEC

Question 282

Which of the following is a beneficial but not an essential plant nutrient?
A) Ni
B) Cl
C) Se
D) Al

Answer 282

C) Se

Question 283

Plant-growth limiting deficiencies are generally rare in areas of significant atmospheric ___ - ___.

Answer 283

Cl-deposition

Question 284

Na in Soils: Na content in Earth’s crust is about ___%, while soils contain 0.1-1%. Low Na in soils indicates weathering of Na from Na-containing minerals. Soil solutions contain between 0.5 and 5 ppm Na⁺ in temperate regions.

Answer 284

2.8%

Question 285

Early sources of phosphate fertilizer were mostly animal-based ___, ___, ___.

Answer 285

bones, guano, manure

Question 286

In addition to the cell wall structure, B is essential for the normal ___ of water, nutrients, and photosynthetic sugars too rapidly developing ___ such as root tips, leaves, buds, and storage tissues.

Answer 286

transport

tissues

Question 287

Mineral Fe is the ___ most abundant element, comprising about _% of Earth’s crust.

Answer 287

fourth

5

Question 288

Fe/Al Oxides: Mo is strongly adsorbed to Fe/Al ___ ___.

Answer 288

oxide surfaces

Question 289

Adsorbed B: B adsorption and desorption can ___ solution B, which ___ B leaching potential. It is a major form of B in ___, high-B soils.

Answer 289

buffer

reduces

alkaline

Question 290

Mn⁺² moves to the root surface by ___ of chelated Mn⁺², like Fe. Solution Mn⁺² is ___ under low pH and low O₂ conditions.

Answer 290

diffusion

increased

Question 291

Ca⁺² is essential for the ___ of carbohydrates and nutrients.

Answer 291

translocation

Question 292

Soil pH and Bicarbonate: Fe deficiency is most often observed on ___-pH and ___ soils in ___ regions, but it can occur in acid soils low in total Fe.

Answer 292

high-pH

calcareous

arid

Question 293

Application of ___may result in elevated levels of Ni in crop plants. Plant ___ have recently been identified from wild mustard, Thlaspi goesingense, which enable plants to accumulate high levels of Ni.

Answer 293

biosolids

genes

Question 294

When released through weathering of primary rocks, Mn will combine with O₂ to form ___ ___.

Answer 294

secondary minerals

Question 295

P mineralization occurs when C/P < XXX:1 (P>0.3%)

Answer 295

200

Question 296

Soil pH: B availability ___ with increasing soil pH, especially at pH > 6.5. Liming acid soils can cause a ___ B deficiency in susceptible plants.

Answer 296

decreases

temporary

Question 297

Initial ___ ___ appears as light green leaves, ultimately turning yellow.

Answer 297

S deficiency

Question 298

___ and ___ __ fractions buffer the increase in solution P through P adsorption on mineral surfaces, precipitation as secondary P minerals, and immobilization as microbial or organic.

Answer 298

Inorganic
organic P

Question 299

How many lbs of KCl (muriate of potash, 60% K₂O) is needed to increase a 0.1 meq K⁺/100 g soil to 0.3 meq/100 g soil? (Assume molecular weight K=39, O=16, Cl=35.5 and 1 acre = 2 million lbs.)

Answer 299

K_increase = (0.2 meq/100 soil) x (39 mg K/meq) = 7.8 mg K/100 g = 0.078 g K/100 g = 0.078 lb K x 20,000 = 1,560 lb K/a

KCl needed = 1,560 lb K/a x (39 + 35.5)/39 = 2,980 lb/a

Question 300

P mobility in plants is _____

Answer 300

mobile

Question 301

Soil pH: Zn⁺² availability ___ with ___ soil pH.

Answer 301

decreases

increasing

Question 302

There are eight plant essential micronutrients, five are taken up as anions, and three as cations.

Answer 302

False

Question 303

Accumulation of ___ leaves under Ca⁺² stress decreases ___ content of stems and roots, which impairs normal ___ function.

Answer 303

carbohydrate

carbohydrate

root

Question 304

B fertilizers should be uniformly soil-applied because of the ___ range between ___ and ___.

Answer 304

narrow

deficiency and toxicity

Question 305

Soil Solution Fe: Compared with other cations, the solubility of common Fe minerals in the soil is very low depending on pH. For each pH unit increase, Fe⁺³ concentration decreases a thousandfold. And, Fe⁺² decreases a hundredfold for each unit increase in pH.

Answer 305

True

Question 306

What are five genotype differences relating to crops sensitivity to Cu?

Answer 306

1) differences in Cu absorption rates
2) greater soil exploration
3) increased Cu solubility
4) more efficient Cu transport from roots to shoots
5) lower Cu requirement

Question 307

Photosynthesis is CO₂ assimilation therefore if _ is increased then respiration increases as well.

Answer 307

K

Question 308

P Loss: fixation by soil oxides, plant uptake, adsorption, immobilization, precipitation, leaching, runoff, erosion, etc

Answer 308

True

Question 309

The original source of soil S is ___ ___ minerals that ___ during weathering from S^-2 to SO₄^-2.

Answer 309

metal sulfide

oxidize

Question 310

Carbohydrate and Lipid Metabolism: If photosynthesis is impeded by ___ deficiency during the vegetative growth stage, then carbohydrate production and plant growth are reduced.

Answer 310

Cu

Question 311

Nearly all chloride (Cl^-) in soils exists in ___ ___.

Answer 311

soil solution

Question 312

Organic Mn: Mn concentration in most animal wastes is like Zn, ranging from __ to __%Mn. Average application rates of most manures will provide sufficient plant-available Mn. As with Fe, Zn, and Cu, the primary benefit of an organic waste application is increased OM and associated natural chelation properties increasing Mn availability.

Answer 312

0.01 to 0.05%

Question 313

A soil contains 2% OM with a 2% loss each year (8:1 N:S). A clover crop grown on this soil yields 10,000 lbs/a (N:S = 12:1, 3% N content).

1. Calculate the amount of S mineralized each year (lbs/a)
2. Is the mineralized S enough for S needed?
3. How many lbs/a of CaSO₄.2H2O would be required if S mineralized in (b) is not enough?

Answer 313

1. Calculate the amount of S mineralized each year (lbs/a)

Total OM in an acre = 2x10⁶ x 0.02 = 40,000 lb OM

Total OM 2% Mineralized = 40,000 x 0.02 = 800 lb OM

N mineralized = 800 lb OM x 0.05 = 40 lb N/afs

S mineralized = 40 lb N/afs / 8 = 5.0 lb S/afs

1. Is the mineralized S enough for S needed?

S needed = ((10,000 lbs/a) x 0.03) / 12 = 25 lb S/afs

S needed is greater than S mineralized therefore addition S will be required.

1. How many lbs/a of CaSO₄.2H₂O would be required if S mineralized in (b) is not enough?

S required = 25 – 5.0 = 20.0 lb S/afs

Question 314

Fe toxicities commonly occur in plants grown on ___ and/or ___ drained soils.

Answer 314

acid

poorly

Question 315

The stability of phosphate enables it to participate in the numerous energy capture, transfer, and recovery reactions that are vital for plant growth.

Answer 315

True

Question 316

Foliar B application is practiced for ___ tree fruit crops, often combined with pesticides.

Answer 316

perennial

Question 317

Flooding: When soils are submerged, the concentration of many nutrients increases, but not ___.

Answer 317

Zn

Question 318

K is essential for photosynthesis through ___ synthesis.

Answer 318

ATP

Question 319

Estimate the annual excess P applied with 3 t/a swine waste (2%N; 1.5%P), where crop yield is 3 t/a (0.3% P).

Answer 319

Excess P = Applied – Crop Yield Removed = (3 t/a x 0.015) – (3 t/a x 0.003) = 0.036 P t/a

Question 320

___ and ___ are closely associated with animal nutrition and are essential for energy transfer and utilization.

Answer 320

P and Ca

Question 321

Inorganic Mo - Mo fertilizers are generally applied at ___ rates (0.03–1 lb/a), depending on the application method. Mo solutions are soil or ___ applied or applied as a seed coating. Seeds treated with a solution of ___ molybdate are widely used because of the low application rates needed. To obtain the satisfactory distribution of the small quantities of Mo applied to soil, Mo sources are sometimes combined with ___ fertilizers. Foliar spray applications with NH₄^- or Na-molybdate are also effective in correcting ___.

Answer 321

low

foliar

Na

N-P-K

deficiencies

Question 322

Mineral Mn: Mn concentration in Earth’s crust averages ≈ ___ ppm, and Mn is found in most Fe-Mg rocks.

Answer 322

1000

Question 323

_ ___ increases crop damage by bacterial and fungal diseases, insect and mite infestation, and nematode and virus infection.

Answer 323

K stress

Question 324

With increasing P deficiency, the dark green color changes from a ___-___ to ___-___.

Answer 324

greyish green

bluish-green

Question 325

While Ca⁺² is important for ___, Ca⁺² is generally ___ in the plant.

Answer 325

translocation

immobile

Question 326

Inorganic Fe: Fe ___ is one of the most difficult micronutrient deficiencies to correct in the field. Fe deficiencies are corrected mainly ___ application of inorganic Fe.

Answer 326

chlorosis

foliar

Question 327

Monoammonium phosphate (MAP) is produced by reacting 1-mole ___ with 1 mole of ___ ___.

Answer 327

ammonia

phosphoric acid

Question 328

Rock phosphate is mined for P fertilizer and this resource will last for millions of years even if its current use is increased many folds.

Answer 328

False

Question 329

Fe is absorbed by roots as ___ or ___.

Answer 329

Fe⁺² or Fe⁺³

Question 330

Cl^- Deficiency and Toxicity Symptoms: Chlorosis in ___ leaves and an overall wilting of plants are the most common symptoms.

Answer 330

younger

Question 331

Which of the following does not contribute to soil solution K?
A) K fixation by 2:1 minerals
B) adding K containing fertilizers to soil
C) K desorption from exchangeable K
D) mica dissolution

Answer 331

A) K fixation by 2:1 minerals

Question 332

___ ___ is characterized by a reduced plant growth rate, where plants are stunted, thin-stemmed, and chlorotic.

Answer 332

S deficiency

Question 333

K is not a component of ___ ___ in plants.

Answer 333

biochemical compounds

Question 334

Solution SO₄^-2 is transported to roots by ___ ___ and ___ and can be leached through the soil profile.

Answer 334

mass flow and diffusion

Question 335

_ ___ generally increases with increasing OM content.

Answer 335

S availability

Question 336

List three primary sources of Si fertilizers.

Answer 336

1. Calcium silicate slag (CaAl₂Si₂O₈) 18-21% Si
2. Calcium metasilicate (CaSiO₃) 31% Si
3. Sodium Metasilicate (NaSiO₃) 23% S

Question 337

____ is an essential element in DNA and RNA that contain the genetic code of the plant

Answer 337

P

Question 338

Soil Moisture and Temperature - With low soil moisture, water films around soil particles are thinner and discontinuous, resulting in a more tortuous path for K⁺ diffusion to roots. Increasing K levels or soil moisture content increases K diffusion.

Answer 338

True

Question 339

Total Mn in soils is between ___ and ___ ppm, averaging about ___ ppm. Mn in soils occurs as various oxides and hydroxides coated on soil particles, deposited in cracks and veins, and mixed with Fe oxides and other soil conditions.

Answer 339

20 and 3,000

600

Question 340

Small quantities of SO₂ can be absorbed through plant ___ and utilized by plants.

Answer 340

leaves