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Quiz on Soil Science Final - Quiz, created by Meagan F on 10/12/2016.

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Soil Science Final - Quiz

Question 1 of 106

1

In nature, beneficial mycorrhizae form with the roots of ____.

Select one of the following:

  • coniferous trees

  • grasses

  • legumes

  • broad leaf trees

  • all of these

Explanation

Question 2 of 106

1

The second most important biological process on earth is

Select one of the following:

  • photosynthesis

  • nitrogen volatilization

  • sulfur oxidation

  • nitrification

  • none of the above

Explanation

Question 3 of 106

1

The site of nutrient transfer between a plant and an ectomycorrhizal fungus is called the _____.

Select one of the following:

  • arbuscule

  • Hartig net

  • mantle

  • absorptive hyphae

Explanation

Question 4 of 106

1

Nitrogenase enzyme activity is inhibited by:

Select one of the following:

  • high oxygen

  • low available C

  • low pH

  • all of these

  • none of these

Explanation

Question 5 of 106

1

The site of nutrient transfer between a plant and an endomycorrhizal fungus is called the ____.

Select one of the following:

  • arbuscule

  • Hartig net

  • mantle

  • absorptive hypphate

Explanation

Question 6 of 106

1

Select from the dropdown lists to complete the text.

Nitrogen fixing bacteria move through a(n) ( root cortex, infection thread, stomate ) to the ( nodules, stem ) which are produced by the plant in the cortical cells, where they reproduce and begin to fix nitrogen.

Explanation

Question 7 of 106

1

During symbiotic nitrogen fixation, the plant benefits by:

Select one of the following:

  • gaining nitrogen

  • gaining carbon

  • getting protection against pathogens

  • the acidification of the root zone

  • none of the above

Explanation

Question 8 of 106

1

Ectomycorrhizae:

Select one of the following:

  • penetrate the root cortex cells and produce tree-like structures for nutrient exchange with the plant

  • create a net-like structure between root cortex cells and on the outside of the roots

  • create nodules inside root cells where nutrient exchange with the plant takes place

  • kill the roots and reduce plant nutrient uptake

Explanation

Question 9 of 106

1

Select from the dropdown lists to complete the text.

( Leghemoglobin, Hemoglobin ) is produced by the ( plant, bacteria ) to maintain ( high, low ) levels of ( carbon dioxide, oxygen ) required for nitrogenase activity.

Explanation

Question 10 of 106

1

The main benefit for the plant of having a symbiotic relationship with mycorrhizal fungi is:

Select one of the following:

  • increased nitrogen availability

  • increased root surface area for nutrient uptake

  • protection against root pathogens

  • increased oxygen in the root for cellular respiration

Explanation

Question 11 of 106

1

Nitrogen is a component of which essential plant compounds?

Select one of the following:

  • chlorophyll

  • enzymes

  • DNA

  • all of the above

Explanation

Question 12 of 106

1

At low soil pH,

Select one of the following:

  • all nutrients are at deficient levels

  • Ca, Mg, and P are at deficient levels, and Al is at toxic levels

  • Most nutrients tend to be at toxic levels

  • Ca, Mg, and P are at toxic levels, and Al is fixed in insoluble compounds

  • All nutrient elements are at levels that support good plant growth

Explanation

Question 13 of 106

1

Select from the dropdown lists to complete the text.

Soils in humid climates tend to acidify ( faster___, slower ) than soils in dry climates because there is ( more, less ) leaching of ( acidic, basic ) cations.

Explanation

Question 14 of 106

1

Which of the following would not be a liming material?

Select one of the following:

  • MgCO₃

  • Ca(OH)₂

  • CaSiO₂

  • CaSO₄

  • All of these are lime

Explanation

Question 15 of 106

1

Select from the dropdown list to complete the text.

The type of microorganism that becomes dominant in the final stage of decomposition and breaks down chitin, cellulose, lignins, and waxes is ( Fungi, protists, actinomycetes, bacteria ).

Explanation

Question 16 of 106

1

Predators that help regulate decomposition rate include:

Select one of the following:

  • Protists and nematodes

  • Bacteria and fungi

  • Actinomycetes

  • Termites

Explanation

Question 17 of 106

1

Humus is in which pool of organic matter?

Select one of the following:

  • active

  • slow

  • rapid

  • passive

Explanation

Question 18 of 106

1

The humus pool of soil organic matter

Select one or more of the following:

  • has a C:N of about 10:1

  • decomposes within 1 to 2 years

  • is very stable

  • decomposes within 5 to 10 years

Explanation

Question 19 of 106

1

Which of the following statements is true about soil organic matter?

Select one of the following:

  • It cannot be increased in the soil indefinitely

  • Application to the soil always leads to lots of immediately available nitrogen

  • It breaks down more rapidly is the soil is tilled

  • A and B only

  • A and C only

Explanation

Question 20 of 106

1

The rate of organic matter decomposition is fastest under which of the following set of conditions?

Select one of the following:

  • Acid pH, moist soils, warm temperatures, good aeration, residues left on soil surface

  • Alkaline pH, dry soils, cool temperatures, good aeration, residues incorporated into soil

  • Neutral pH, moist soils, warm temperatures, poor aeration, residues left on soil surface

  • Neutral pH, moist soils, warm temperatures, good aeration, residues incorporated

Explanation

Question 21 of 106

1

Which of the follow C:N ratios will most likely result in a moderate rate of organic matter breakdown with no short term changes in the soil nitrogen?

Select one of the following:

  • 5:1

  • 25:1

  • 100:1

  • 1000:1

Explanation

Question 22 of 106

1

Long-term tillage tends to reduce the amount of organic matter in a soil because

Select one or more of the following:

  • tillage incorporates residues into the soil

  • tillage reduces soil aeration

  • tillage reduces soil erosion

  • tillage reintroduces oxygen into the soil

Explanation

Question 23 of 106

1

Select from the dropdown lists to complete the text.

In aerobic respiration by microbes, ( N₂, CO₂, O₂ ) is absorbed, and ( O₂, N₂, CO₂ ) is released.

Explanation

Question 24 of 106

1

Soil organisms that reproduce rapidly and degrade the simple compounds found in fresh organic matter added to the soil are the ___.

Select one of the following:

  • fungi

  • rotifers

  • bacteria

  • earthworms

Explanation

Question 25 of 106

1

An important function of humus is to:

Select one of the following:

  • help establish and maintain strong granular soil structure

  • hold onto water very tightly so that only soil microorganisms can use it

  • provide large quantities of quickly available plant nutrients

  • provide easily degradable carbon compounds for soil microorganisms

Explanation

Question 26 of 106

1

Which of the following management practices would most likely be necessary if growing food crops on Spodosols?

Select one of the following:

  • frequent use of soil tillage and conservation

  • use of erosion control measures such as terracing

  • addition of liming agents

  • supplying water through irrigation

Explanation

Question 27 of 106

1

Gelisols:

Select one of the following:

  • are old, deeply weathered soils developed from intrusive volcanic rock

  • contain a permafrost layer within the top 2 meters

  • contain slickensides

  • include all soils with a histic epipedon

  • none of the above

Explanation

Question 28 of 106

1

Slickensides may be found in:

Select one of the following:

  • vertisols

  • mollisols

  • andisols

  • oxisols

  • none of the above

Explanation

Question 29 of 106

1

Andisols:

Select one of the following:

  • are old, deeply weathered soils developed from intrusive volcanic rock

  • contain slickensides

  • form on unstable landscape positions undergoing erosion and deposition

  • contain a permafrost layer within the top 2 meters

  • none of the above

Explanation

Question 30 of 106

1

Ultisols:

Select one of the following:

  • form on unstable landscape positions undergoing erosion and deposition

  • form on old, stable land surfaces in warm humid climates

  • are the most weathered soils

  • contain slickensides

Explanation

Question 31 of 106

1

The role of soil animals in organic matter decomposition is to:

Select one or more of the following:

  • shred and mix fresh organic matter into the soil

  • decompose waxes and lignins

  • feed on bacteria and fungi

Explanation

Question 32 of 106

1

The organic matter content of a loam soil declined from 5% to 2% as a result of continued cultivation/tillage. This will result in:

Select one of the following:

  • deterioration of soil structure

  • deterioration of soil texture

  • stabilization of soil structure

  • increase in crop yield

Explanation

Question 33 of 106

1

The majority of nutrient release occurs during the decomposition of:

Select one of the following:

  • humus

  • the slow pool of organic matter

  • the active pool of organic matter

  • the passive pool of organic matter

Explanation

Question 34 of 106

1

The pool of organic matter most impacted by organic matter additions in agriculture is:

Select one of the following:

  • humus

  • the slow pool

  • the active pool

  • the passive pool

Explanation

Question 35 of 106

1

Select from the dropdown list to complete the text.

The "active" pool usually makes up less than ( 10, 1, 0.1, 0.01 ) percent of the total organic matter in a soil.

Explanation

Question 36 of 106

1

Which of the following are characteristics of the majority of microorganisms involved in soil organic matter decomposition?

Select one of the following:

  • they get C from CO₂ and energy from oxidation of organic compounds

  • they get C and energy from oxidation of organic compounds

  • they get C from CO₂ and energy from oxidation of inorganic compounds

  • none of the above

Explanation

Question 37 of 106

1

The basic unit of soil classification is the:

Select one of the following:

  • order

  • great group

  • family

  • series

Explanation

Question 38 of 106

1

Criteria for grouping soils into orders include:

Select one of the following:

  • soil forming processes as indicated by the presence or absence of major diagnostic horizons

  • the thickness of major diagnostic horizons

  • soil temperature, mineralogy, and particle size

  • the specific location of the soil

Explanation

Question 39 of 106

1

The highest level of soil classification is the family.

Select one of the following:

  • True
  • False

Explanation

Question 40 of 106

1

The soil moisture regime that is used in regions where there are cool, moist winters and long, dry summers with drought is called:

Select one of the following:

  • udic

  • xeric

  • aridic

  • ustic

  • aquic

Explanation

Question 41 of 106

1

The warmest soil temperature regime is called:

Select one of the following:

  • thermic

  • frigid

  • mesic

  • cryic

Explanation

Question 42 of 106

1

The Los Osos soil is classified as an Argixeroll. To what soil Order does it belong?

Select one of the following:

  • Mollisol

  • Vertisol

  • Gelisol

  • Spodosol

  • Alfisol

Explanation

Question 43 of 106

1

This soil order commonly forms out of serpentenite parent material and is characterized as having an abundance of smectite clay. It is not good for building on as it swells during wet periods and shrinks during dry periods.

Select one of the following:

  • Mollisol

  • Aridisol

  • Alfisol

  • Ultisol

  • Vertisol

Explanation

Question 44 of 106

1

The State Soil of California, San Joaquin, is classified as a Durixeralf. To what soil Order does it belong?

Select one of the following:

  • Mollisol

  • Vertisol

  • Gelisol

  • Spodosol

  • Alfisol

Explanation

Question 45 of 106

1

Supposing you want to grow corn, soils of which soil order would be best, based on natural fertility?

Select one of the following:

  • Mollisol

  • Alfisol

  • Aridisol

  • Entisol

  • Ultisol

Explanation

Question 46 of 106

1

Which soil order is commonly found on steep backslope landscape positions or in soils where little or no weathering has taken place?

Select one of the following:

  • Ultisol

  • Entisol

  • Andisol

  • Alfisol

  • Aridisol

Explanation

Question 47 of 106

1

Soils in this order are commonly sandy in texture, quite acidic and develop primarily under coniferous trees in cool to cold climates:

Select one of the following:

  • Mollisols

  • Andisols

  • Spodosols

  • Alifisols

  • Ultisols

Explanation

Question 48 of 106

1

A soil on the dry slopes of the Northern Cascades of California is classified as an Xerept. To what soil Order does it belong?

Select one of the following:

  • Inceptisol

  • Alfisol

  • Mollisol

  • Ultisol

  • Oxisol

Explanation

Question 49 of 106

1

Permafrost is:

Select one of the following:

  • material that remains below 0 degrees Celsius for more than two consecutive years

  • is permanently frozen

  • a surface horizon developed by frost heaving

  • is found in soils in the Order Histosols

  • none of the above

Explanation

Question 50 of 106

1

Aridisols often contain which of the following horizons?

Select one of the following:

  • mollic

  • histic

  • albic

  • calcic

  • none of the above

Explanation

Question 51 of 106

1

Select from the dropdown list to complete the text.

Vertisols develop from parent materials rich in ( K, Ca and Mg, Na, Na and K )

Explanation

Question 52 of 106

1

Which soil order, containing highly weathered soils composed mainly or iron and aluminum oxide clay, is found in the humid tropics?

Select one of the following:

  • Histosol

  • Vertisol

  • Ultisol

  • Oxisol

  • none of the above

Explanation

Question 53 of 106

1

Soils that are commonly sandy in texture, quite acidic and develop primarily under coniferous trees in cool to cold climates often contain which of the following horizons?

Select one of the following:

  • permafrost

  • argillic

  • albic

  • mollic

  • oxic

Explanation

Question 54 of 106

1

Select from the dropdown list to complete the text.

The most dominant soil forming factor for an Aridisol soil would be ( climate, parent material, time, topography, vegetation )

Explanation

Question 55 of 106

1

Characteristics of kaolinite clays include:

Select one of the following:

  • made up of Fe or Al and O, very little net negative charge, positive charge at low pH, low plasticity, stickiness, and water holding

  • significant substitution in the octahedral, layers weakly held together by cations (highly expansible), CEC of 80-120 cmolc/kg

  • significant substitution in the tetrahedra, layers tightly bound (moderately expansible), CEC of 100-180 cmolc/kg

  • significant substitution in the tetrahedra, potassium ions hold clay layers together tightly (non-expansible), CEC of 20-40 cmolc/kg

  • limited isomorphous substitution, layers are H-bonded (non-expansible), CEC of 2-5 cmolc/kg

Explanation

Question 56 of 106

1

The main cations found on the cation exchange complex at a soil pH between 6 and 7 are:

Select one of the following:

  • Ca, Al, H

  • Ca, Mg, K

  • K, Al(OH), Mg

  • Al, H, K

Explanation

Question 57 of 106

1

Which of the following will be readily leached from soils because of the properties it has that influence how tightly they are held on the exchange complex of clay?

Select one of the following:

  • Al

  • H

  • Ca

  • Na

Explanation

Question 58 of 106

1

Two major types of soil colloids are:

Select one of the following:

  • crystalline silicate clays and humus

  • basic cations and humus

  • crystalline silicate clays and quartz sands

  • primary minerals and secondary minerals

  • quartz sands and humus

Explanation

Question 59 of 106

1

Cation exchange capacity is

Select one of the following:

  • the amount of exchangeable negatively charged ions per unit weight of dry soil

  • the amount of exchangeable negatively charged and neutral ions per unit weight of soil

  • the amount of exchangeable positively charged ions held per unit weight of dry soil

  • the amount of exchangeable H ions per unit weight of dry soil

Explanation

Question 60 of 106

1

Which cation would you expect to find tightly held in a soil at pH 4.5?

Select one of the following:

  • K

  • Ca

  • Na

  • Mg

  • Al

Explanation

Question 61 of 106

1

The swelling/shrinking tendency of some silicate clay minerals is due primarily to:

Select one of the following:

  • the presence of cations attracted by the negative charges on the internal surfaces

  • the movement of water molecules in and out of the interlayers of the crystal

  • varying thickness of the film of water covering the external surface of the particles

  • expansion in the width of the interlayers due to movement of larger ions such as K+

  • the high Mg^2+ contents in the octahedral layers

Explanation

Question 62 of 106

1

The accumulation or loss of what compounds result in the formation of hydric soil indicators?

Select one of the following:

  • iron, manganese, sulfur, or carbon

  • nitrogen, phosphorus, or potassium

  • iron, carbon, sulfur, or nitrogen

  • iron, manganese, sulfur, or arsenic

Explanation

Question 63 of 106

1

Which of the follow is not a characteristic of soil colloids?

Select one of the following:

  • very small size

  • high external surfaces

  • electronegativity charges

  • ability to exchange ions with the soil solution

  • low water holding capacity

Explanation

Question 64 of 106

1

Select from the dropdown list to complete the text.

The criteria required to define wetlands are wetland hydrology, hydric soils, and ( water standing on the surface, clay subsoils, hydrophytic vegetation )

Explanation

Question 65 of 106

1

Select from the dropdown list to complete the text.

Conditions required to form hydric soil indicators are elements that reduce, seasonal or permanent water saturation, microorganisms, and ( water standing on the surface, an organic carbon source, hydrophytic vegetation, clay subsoils )

Explanation

Question 66 of 106

1

Select from the dropdown list to complete the text.

The diffusion rate of oxygen in water is 10,000 times ( faster, slower ) than in air.

Explanation

Question 67 of 106

1

Possible ecological consequences of poor soil aeration include:

Select one or more of the following:

  • slow organic matter decomposition

  • release of greenhouse gases into the atmosphere

  • reduced plant photosynthesis

Explanation

Question 68 of 106

1

A major determinant of the aeration status of soils is:

Select one of the following:

  • dominant type of clay present

  • pore size and continuity

  • types of wetland plants present

  • presence or absence of carbonates

Explanation

Question 69 of 106

1

Which type of water includes that which is available to plants?

Select one of the following:

  • hygroscopic water

  • capillary water

  • gravitational water

  • free water

Explanation

Question 70 of 106

1

Water moves through soil to plant roots by:

Select one of the following:

  • capillary flow from high to low water potential

  • hygroscopic flow

  • transpiration

  • capillary flow from low to high water potential

  • gravitational flow

Explanation

Question 71 of 106

1

Water moves further in finer textured soils because:

Select one of the following:

  • the granular structure in fine textured soils allows for stronger attraction between water and particles

  • more space between particles causes the bonds of cohesion between water molecules to be stronger

  • there is less space between the particles and the water film is unbroken for longer distances

  • more water is lost by plant transpiration in fine textured soils

Explanation

Question 72 of 106

1

The bulk of gaseous interchange in soils takes place by:

Select one of the following:

  • mass flow

  • differences in the pressure of N gas

  • diffusion of individual gases along their concentration gradients

  • moving as dissolved ions in soil water

  • aerobic respiration

Explanation

Question 73 of 106

1

Clay soils hold more water but have less PAW than loamy soils because:

Select one of the following:

  • there is less gravitational water in clay

  • plant roots cannot grow as well in clay soils

  • more hygroscopic water is held on clay particles

  • loamy soils have smaller pores

Explanation

Question 74 of 106

1

Sandy soils have less PAW than loamy soils because:

Select one of the following:

  • there is less gravitational water in sandy soil

  • plant roots grow better in sandy soils so they use the water faster

  • more hygroscopic water is held on sand particles

  • sandy soils have less surface area

Explanation

Question 75 of 106

1

Which type of water is not "held" in soils?

Select one of the following:

  • hygroscopic

  • gravitational

  • capillary

  • water of cohesion

Explanation

Question 76 of 106

1

Capillarity in soils:

Select one of the following:

  • involves both adhesion and cohesion

  • is enhanced by the symmetrical nature of the water molecule

  • is independent of the matric potential in soils

  • does not account for unsaturated water movement in soils

Explanation

Question 77 of 106

1

Which type of bond controls retention and movement of water in soils?

Select one of the following:

  • capillary

  • covalent

  • pH-dependent

  • hydrogen

Explanation

Question 78 of 106

1

PAW is highest in soils with the following texture:

Select one of the following:

  • sand

  • sandy loam

  • silty clay loam

  • clay

Explanation

Question 79 of 106

1

The electronegative charge on 2:1 type silicate clays is due primarily to:

Select one of the following:

  • ionization of surface OH groups

  • substitution of one metallic atom for another in the crystal structure

  • extremely small size of the individual colloid particles

  • the effect of pH on the presence of H+ ions in the exchange complex

  • the preponderance of tetrahedron sheets compared to octahedron sheets

Explanation

Question 80 of 106

1

Formation of granular aggregates is aided by:

Select one or more of the following:

  • fungal hyphae

  • fine roots

  • microbial and plant exudates

Explanation

Question 81 of 106

1

Soils developed from accumulated organic material have which of the following characteristics?

Select one of the following:

  • flat, high in clay, and fertile

  • coarse, stony, with fast drainage

  • light, porous, and productive

  • clayey and poorly drained

Explanation

Question 82 of 106

1

Secondary minerals are not found in:

Select one of the following:

  • metamorphic and sedimentary rocks

  • soils and lacustrine sediments

  • soils and sedimentary rocks

  • igneous rocks and the atmosphere

  • soils and metamorphic rocks

Explanation

Question 83 of 106

1

Compared to silt, clay-sized particles are characterized by:

Select one of the following:

  • greater attraction for water

  • greater proportion of primarily minerals

  • less attraction for water

  • less capacity to hold nutrients in plant-available forms

Explanation

Question 84 of 106

1

Fine sand and smaller particles move parallel to the ground and upward by:

Select one of the following:

  • Creep

  • Flow

  • Suspension

  • Turbulence

  • Saltation

Explanation

Question 85 of 106

1

Which of the following would NOT reduce water erosion by controlling soil detachment?

Select one of the following:

  • barriers

  • stubble mulching

  • conservation tillage

  • cover crops

  • no-till farming practices

Explanation

Question 86 of 106

1

Causes of soil erosion include:

Select one or more of the following:

  • over-harvesting timberland

  • overgrazing rangeland

  • fire

  • poor farming practices

Explanation

Question 87 of 106

1

Select from the dropdown list to complete the text.

Terracing is a means of reducing ( soil transport by wind, soil detachment, soil transport by water, soil saltation in wind )

Explanation

Question 88 of 106

1

Select from the dropdown list to complete the text.

When water concentrates in small channels as it runs from the soil surface, it is called ( gully, wind, rill, sheet ) erosion.

Explanation

Question 89 of 106

1

The majority of soil particle movement during wind erosion occurs as:

Select one of the following:

  • Creep

  • Flow

  • Suspension

  • Turbulence

  • Saltation

Explanation

Question 90 of 106

1

Select from the dropdown list to complete the text.

The total global soil lost through erosion is generally greater from ( gully, rill, sheet, wind ) erosion.

Explanation

Question 91 of 106

1

Land degradation includes which of the following effects on soil?

Select one or more of the following:

  • decline in soil structure

  • reduced microbial biomass

  • salinization

Explanation

Question 92 of 106

1

Sulfuric acid can be used instead of gypsum to reclaim sodic soils that contain:

Select one of the following:

  • a high buffering capacity

  • free NaCO₃

  • free CaCO₃

  • a high CEC

Explanation

Question 93 of 106

1

The exchangeable sodium percentage (ESP):

Select one of the following:

  • predicts soil pH by indicating the amount of sodium there is in the soil in relation to the H ions on the exchange complex

  • predicts soil CEC by calculating the amount of sodium there is on the exchange complex

  • expresses the ratio of sodium to aluminum in the octahedral sheet of 2:1 clays

  • indicates the hazard of sodium-induced soil dispersion

Explanation

Question 94 of 106

1

Under what precipitation-to-ET conditions would the most severe soil salinization develop?

Select one of the following:

  • Ratio of 0.25

  • Ratio of 0.75

  • Ratio of 1.25

  • Ratio of 2.25

Explanation

Question 95 of 106

1

Your soil begins to disperse and crop yields decline several years after you start irrigating your garden plot. Which of the following would most likely account for this situation?

Select one of the following:

  • high content of Ca and Mg in the irrigation water

  • high content of Na in the irrigation water

  • excessive drainage of the soil

  • high gypsum content in the soil

Explanation

Question 96 of 106

1

Sodic soils generally have a poor physical condition. This is most likely due to:

Select one of the following:

  • low OM content

  • dispersal of the Na saturated soil colloids

  • impact of raindrops on the soil surface

  • precipitation of the Ca and Mg ions as carbonates

  • high content of smectite in the soils

Explanation

Question 97 of 106

1

Techniques for managing saline soils include:

Select one or more of the following:

  • keeping the plant root zone wet during sensitive crop stages

  • adding CaCO₃ to replace the Na on the exchange complex

  • applying excess water to increase leaching

Explanation

Question 98 of 106

1

Overliming:

Select one or more of the following:

  • may occur on coarse-textured soils with low OM

  • may result in NH₃ volatilization if NH₄ is present

  • may result in Fe, Mn, Cu, Zn, P, and B deficiencies

Explanation

Question 99 of 106

1

The major role of potassium in plants is:

Select one of the following:

  • as part of the chlorophyll molecule

  • regulating cellular respiration

  • energy storage

  • regulating the opening and closing of stomates

Explanation

Question 100 of 106

1

Select from the dropdown list to complete the text.

Organic forms of P make up about ( 98%, 50%, 25%, 1% ) of total P in the soil.

Explanation

Question 101 of 106

1

Select from the dropdown list to complete the text.

Available forms of potassium in the soil usually make up about ( 95-98%, 25-50%, 10%, 0.1-2% ) of total potassium.

Explanation

Question 102 of 106

1

Select from the dropdown list to complete the text.

The process of ( nitrification, denitrification, symbiosis, volatilization, mineralization ) releases soluble nitrogen as the result of the breakdown of nitrogen-rich organic compounds.

Explanation

Question 103 of 106

1

Select from the dropdown lists to complete the text.

( Nitrification, Denitrification, Volatilization, Mineralization ) is the process of reduction of NO₃₋ to nitrogen gas by microorganisms under ( aerobic, anaerobic, acidic, alkaline ) soil conditions.

Explanation

Question 104 of 106

1

Select from the dropdown list to complete the text.

A pH in the range of ( 3.5-4.5, 4.5-5.5, 5.5-7.0, 7.0-8.0, >8.0 ) is when phosphorus is most available to plants.

Explanation

Question 105 of 106

1

The highly mobile form of N, which is the main source of N for plants, is:

Select one of the following:

  • NH₃

  • NH₄

  • NO₃

  • N₂

Explanation

Question 106 of 106

1

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The nutrient most limiting for growing food crops in the world is ( phosphorus, carbon, nitrogen, potassium ).

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