ENV370 exam 2
Alternate freezing and thawing of soils results in the "heaving" of plants and the destruction of shallow building foundations. This effect is due primarily to __________. A) the expansion of water when it freezes B) the wetting and drying of swelling-type clays C) pressure from upward movement of water from lower horizons D) the breaking down of soil aggregates due to freezing and thawing E) the hydration of adsorbed cations on the soil colloids
A
Capillarity in soils ______ A) involves both adhesion and cohesion B) is enhanced by the symmetrical nature of the water molecule C) is independent of the matric potential in soils D) is not involved in the process of water uptake from soils E) does not account for unsaturated water movement in soils
A
Compared to upland soils, wetland soils would be characterized by an abundance of ______ A) methane B) CO2 C) NO3- D) SO4 2- E) Fe3+
A
Forest fires result in sufficiently high soil temperatures to cause the vaporization and movement of certain organic compounds in soils. The main effect of these compounds is to _______. A) reduce water infiltration and percolation through the profile B) enhance soil structural stability C) increase pH D) decrease water losses by surface runoff E) increase soil organic matter
A
If you were seeking a soil colloid with a high capacity to adsorb cationic pollutants, but also with a consistent capacity to do so even as the pH varied form 4.0 to 7.5, which of the following would you choose? A) montmorillonite B) kaolinite C) fine-grained mica D) humus E) chlorite
A
In which of the following "forms" of soil water are pesticides, excess plant nutrients, and waste chemicals most apt to move through soils? A) gravitational B) unsaturated C) available D) hygroscopic E) capillary
A
In which of the following situations would you expect downward movement of soil water through the profile to be most rapid? A) uniformly textured sandy loam profile B) sandy loam in upper layers with a clay band underneath C) sandy loam in upper layers with a layer of coarse gravel underneath D) clay texture throughout the profile E) silt loam in upper layers underlain by a sandy layer
A
Some soil colloids exhibit positive charges under highly acid conditions. To what are these charges likely due? A) protonation of some hydroxy groups by excess H+ ions B) the adsorption of Al3+ ions on the colloid C) the release of some OH- ions leaving an unsatisfied positive charge on the colloid D)substitution of lower valent atoms for higher valent atoms in the octahedral sheet E) increase in the level of H+ ions on the exchange complex
A
The likelihood of polluting groundwater with pesticides and plant nutrients is enhanced by _____. A) the presence of macropores in the soil B) light tillage of the upper centimeter or so of soil C) the use of tillage to control weeds D) the production of oats rather than wheat E) conventional tillage as a choice compared with conservation tillage
A
The negative charges associated with smectite clay crystals are due mostly to _________ A) isomorphous substitution of Mg for Al in the octahedral sheet B) substitution of Al for Mg in the tetrahedral C) high pH associated with the formation of the mineral D) substitution of Si for Al in the tetrahedral sheet E) OH groups on the external surface of the crystal
A
The osmotic potential would likely be the lowest in soils of which of the following orders? A) aridisols B) histosols C) Oxisols D) ultisols E) Spodosols
A
Urban development of land under natural vegetation or agriculture usually greatly _________ soil infiltration capacity and therefore greatly increases __________ A) decreases, stream bank erosion B) increases, stream bank erosion C) decreases, groundwater recharge D) increases, groundwater recharge
A
the following is the reduced form of the essential element depicted A) NH4+ B) Fe3+ C) CO2 D) SO4 2- E) Fe3+
A
Which of the following statements concerning applications or capabilities of soil moisture measuring devices is (are) true for the neutron probe? A) requires destructive sampling for each measurement B) good to turn on automatic irrigation at -50 kPa C) used to turn on irrigation when soil moisture potential reaches -200 kPa D) would give the same reading for both a loamy sand and a silt loam if both contained 15% moisture E) both A and D
D
Which of the following would you expect to have the highest leaf area index? A) bare fallowed area B) corn three weeks after planting C) corn, knee high D) alfalfa just before harvest E) Either B or C (equal)
D
Which of the silicate clays would likely have the highest level of potassium in the crystal structure? A) kaolinite B) chlorite C) smectite D) fine-grained mica E) vermiculite
D
At which of the following soil moisture potentials (expressed as kPa) is the soil water held most tightly? A) +5 B) 0 C) -31 D) -1500 E) -3100
E
At which of the following soil moisture potentials (expressed as kPa) is the waters' energy level the lowest? A) +5 B) 0 C) -31 D) -1500 E) -3100
E
Groundwater _____________ A) is a source of water above the vasodose zone in a soil B) moves downward in the vasodose zone through the capillary fringe C) moves laterally but not vertically below the soil profile D) is found mostly in shallow layers just below the argillic E) is a major source of water for irrigation in the US
E
Plant roots obtain access to soil water in which of the following ways? A) the roots contract and leave room in the pores for the water to move in B) Roots extend into moist soil area C) water vapor moves from the wet soil areas to the root surfaces D) water flows to the roots by capillarity E) both B and D
E
Plant transpiration efficiency at a given location is markedly influenced by __________. A) organic residue cover on the soil B) tillage practices used C) fertilization practices used D) the plant species being grown E) both C and D
E
Soil A has a redox potential of 400 mV, soil B -200 mV. Of the two soil, Soil A is more apt to be characterized by an abundance of _________. A) Fe 2+ ions B) Mn 2+ ions C) H+ ions D) S2- ions E) molecular oxygen
E
Soils rich in which type of clay would provide the most troublesome site on which to build a home? A) Fe, Al oxides B) kaolinite C) fine-grained mica D) chlorite E) smectite
E
The partial pressure of oxygen in the atmosphere is 0.21 bar and that of nitrogen 0.78. which of the following partial pressure levels would you expect to find in the pores of a moderately well-drained soil? A) 0.21 (oxygen) B) 0.80 (nitrogen) C) 0.30 (oxygen) D) 0.50 (nitrogen) E) 0.15 (oxygen)
E
The water content in a soil is known to be 0.2 m3/m3 and the potential of pure water outside the system is assumed to be 0. If the soil is a clay loam you would calculate the soil water potential (in kPa) to be A) 0 B) -5 C) 20 D) -20 E) impossible to calculate with the data given
E
Unsaturated water flow _________ A) is faster than saturated flow B) is driven primarily by the force of gravity C) is stimulated by the osmotic potential D) is slower on sands than on clays if the soil moisture content is high E) occurs on soils that are at field capacity
E
Which of the following actions would best assure good aeration in a soil? A) increase the soil temperature B) add organic residues C) use a plastic mulch D) use cover crops, especially legumes E) remove excess water
E
Which of the following is (are) considered necessary features for an area to be delineated as a wetland? A) hydric soils B) shallow standing water C) aquatic vegetation D) organic soils E) all of the above
E
Which of the following is not a characteristic of soil colloids? A) very small size B) high external surfaces C) electronegative charges D) ability to exchange ions with the soil solution E) low water holding capacity
E
Which of the following silicate clays would be least apt to be formed from the mere alteration of primary minerals? A) smectite B) vermiculite C) chlorite D) fine-grained mica E) iron and aluminum oxides
E
Which of the following statements concerning applications or capabilities of soil moisture measuring devices is (are) true for the use of a drying oven and balance? A) requires destructive sampling for each measurement B) good to turn on automatic irrigation at -50 kPa C) used to turn on irrigation when soil moisture potential reaches -200 kPa D) would give the same reading for both a loamy sand and a silt loam if both contained 15% moisture E) both A and D
E
Which of the following will increase the evaporation (E) from the soil surface? A) adding straw mulch to the soil surface B) the use of no-till culture C) stubble mulch farming D) plastic mulch E) none of the above
E
T or F: The average residence time for water in clouds over the ocean is about one year
F
T or F: The water potential in soils is generally considered lower than that in the atmosphere
F
T/F: respiration by plant and animal cells along with photosynthesis releases oxygen and cosumes CO2
F
True or false: A tetrahedral sheet is characterized by a plane of aluminum atoms surrounded by oxygen and hydroxyl groups
F
True or false: the order of strength of adsorption of ions by most colloids when they are present in equivalent quantities is Al>Ca>K>Mg>Na
F
T/F: if the CO2 content of soil air is 3.5%, it is 100 times higher than that of the atmosphere
T
T/F: the partial pressure of CO2 in the soil pores is higher than the partial pressure of this gas in the atmosphere
T
True or False: Kaolinite is most prevalent in soils developed from volcanic ejecta (andisols)
T
True or false: the leaf-like structure of silicate clays involves two kinds of horizontal sheets, one dominated by a plane of silicon atoms, the other by a plane of aluminum and/or magnesium
T
True or false?: soil colloids are too small to be seen with an ordinary light microscope?
T
As biotite weathers in soils, which of the following would not likely develop by mere alteration of this mineral? A) fine-grained mica B) kaolinite C) smectite D) chlorite E) vermiculite
B
The electronegative charge on 2:1 type silicate clays is due primarily to _________ A) ionization of surface OH groups B) substitution of one metallic atom for another in the crystal structure of the clay C) extremely small size of the individual colloid particles D) the effect of pH on the presence of H+ ions in the exchange complex E) the preponderance of tetrahedral sheets compared to octahedral sheets
B
The evapotranspiration (ET) from a pine forest was found to be 50 cm during a growing season. If the evaporation from the soil surface during this period of time was 5 cm, what is the level of loss from leaf surfaces? A) 55 cm B) 45 cm C) 50.0 cm D) 10 cm E) impossible to calculate from the data given
B
The expression, P - ET - SS estimates the ________ a watershed. A) soil water content of B) discharge volume from C) evaporation from D) interception in
B
The matric potential of soil water is _______ A) influenced greatly by the content of salts in the soil B) not influenced appreciably by the force of gravity C) is generally higher than that of pure water D) is little effected by soil solids E) is lower in a sandy soil with 20% soil water than in a clay soil with same percentage of moisture
B
The most common form of on-site waste water treatment for homes not hooked up to sewer lines is the ________ A) active composting method B) septic tank and drain field C) chemical "flush" system D) electrical induction sterilization E) soil enrichment purposes
B
The redox potential is a measure of _______ A) molecular oxygen content B) the tendency of a substance to accept or donate electrons C) carbon dioxide content D) the ferric ion content E) the balance between hydrogen and hydroxyl ions in solution
B
The swelling/shrinking tendency of some silicate clay minerals is due primarily to ____________ A) the presence of cations attracted by the negative charges on the internal surfaces B) the movement of water molecules in and out of the interlayers of the crystal C) varying thickness of the film of water covering the external surface of the particles D) expansion in the width of the interlayers due to movement of larger ions such as K+ E)the high Mg2+ contents in the octahedral layers
B
Which of the following best characterizes the field capacity of a soil? A) maximum capacity of a soil to hold water B) water content of a soil with water potential of about -10 kPa C) the total capillary water of a soil D) a wetted soil prior to the removal of the gravitational water E) soil with water potential of -1500 kPa
B
Which of the following is not true with respect to the hydrologic cycle? A) More than 85% of the water evaporated from the earth's surface comes from oceans B) there is a net migration of some 40,000 km3 of water in clouds from the land area to the ocean areas C) the average residence time of water in clouds is about 10 days D) some 78% of the total precipitation falls onto the oceans E) about on third of the readily accessible water in the hydrologic cycle is in the soil
B
Which of the following sources of water have the shortest average residence time? A) soil moisture B) clouds C) oceans and ice caps D) groundwater
B
Which of the following statements concerning applications or capabilities of soil moisture measuring devices is (are) true for the tensiometer? A) requires destructive sampling for each measurement B) good to turn on automatic irrigation at -50 kPa C) used to turn on irrigation when soil moisture potential reaches -200 kPa D) would give the same reading for both a loamy sand and a silt loam if both contained 15% moisture E) both A and D
B
Which of the following will not increase the efficiency of water use by plants in an irrigation system? A) the use of concrete-linked delivery ditches B) the use of flood irrigation for forage crops C) the use of drip irrigation for fruit trees D) the use of crop residues to reduce evaporation E) the use of herbicides to control weeds
B
Allophane differs from other silicate clays in all ways but one of the following (select the one). A) nature of parent material B) degree of crystallization of the particles C) the presence of negative charges on the colloidal particles D) widespread occurrence around the the world E) the period of time it has been subject to weathering
C
If you owned a dairy farm with poorly drained clay soils in a humid temperate region which of the following would be most satisfactory from the standpoint of soil aeration and temptation? A) no-till system B) conventional moldboard plow system C) ridge-till system D) heavy organic residues E) heavy chemical fertilization
C
If you were looking for a soil with a high cation exchange capacity and were not concerned with the soil's physical properties, which of the following would most likely fit your needs? A) aridisol B) oxisol C) vertisol D) mollisol E) ultisol
C
Soil high in organic matter commonly hold more available water than comparable soils with lower organic matter levels. This is most likely due to what characteristics of the high OM soils? A) larger micropore space B) lower permanent wilting point C) higher field capacity D) higher capacity of the OM to hold water tightly E) higher clay content
C
The bulk of gaseous interchange in soils takes place by ________ A) mass flow B) partial pressure of N2 C) diffusion D) dissolution of water E) respiration
C
The following are characteristics of a water molecule A) the H to O to H angle is approximately 90 degrees B) the two H atoms are on diametrically opposite ends of the molecule C) It has a positive and a negative side D) it is attracted to surfaces with negative but not positive charges E) it is held in soils by adhesion but not adsorption
C
The redox potential of a soil is -250 mV. which of the following forms of the pertinent elements would you expect to find in the soil? A) NO3- B) SO4 2- C) Fe2+ D) Mn4+ E) CO2
C
Which cation would you expect to be mostly tightly held in a soil at pH 4.5? A) K+ B) Ca2+ C) Al3+ D) Mg2+ E) Na+
C
Which of the following irrigation systems produces the most biomass per unit of water applied? A) flood irrigation B) furrow irrigation C) drip irrigation D) sprinkle irrigation E) furrow-dike irrigation
C
Which of the following is not a major factor in determining the soil aeration status? A) redox potential B) volume of macropores C) nitrogen gas D) carbon dioxide E) oxygen
C
Which of the following locations in the US would have the highest evaporation (E) from the soil surface in July? A) a bare, unirrigated dry land soil in Colorado B) an unirrigated soil in South Carolina growing cotton C) a furrow-irrigated cotton field in Arizona D) a forest woodland in Illinois E) a corn field in New York
C
Which of the following means of estimating soil water levels gives a direct measurement of the water content? A) gypsum blocks B) neutron scattering C) gravimetric determinations D) tensiometer E) pressure membrane
C
Which of the following statements concerning applications or capabilities of soil moisture measuring devices is (are) true for the electrical resistance block? A) requires destructive sampling for each measurement B) good to turn on automatic irrigation at -50 kPa C) used to turn on irrigation when soil moisture potential reaches -200 kPa D) would give the same reading for both a loamy sand and a silt loam if both contained 15% moisture E) both A and D
C
A well aerated soil is characterized by a relative abundance of ________. A) micropores B) Fe2+ ions C) NH4+ ions D) NO3- ions E) methane gas
D
A well drained soil under a rain forest in Brazil contains significant amounts of a silicate clay. Which of the following is it most apt to be? A) chlorite B) fine-grained mica C) smectite D) kaolinite E) vermiculite
D
Humus is an important soil colloid. It differs from 2:1 type minerals in all but one of the following characteristics: A) structural framework of the particles B) CEC dependence on soil pH C) influence of isomorphous substitution D) capable of adsorbing cations E) influence on soil aggregate stability
D
Land drainage is beneficial because _________ A) it increases the alternate expansion and contraction due to freezing and thawing of soils B) it increases the water-to-air ratio in the soil pores C) it slows down the rate of soil warming in the spring D) it increases the depth of root penetration in the soil E) it increases the availability of iron and manganese in acid soils
D
Of the various types of drain systems, open ditch systems are most practical and economical for use on __________ A) vertisols B) soils which do not freeze during the winter C) soils with a deep water table D) poorly drained soils with sandy profiles E) clay soils with poor drainage
D
The primary characteristic of subsoils that accounts for the ability of ground circulation heat pumps to moderate temperatures in houses in both summer and winter is _______ A) the high redox potential of the soil B) the high heat of the evapotranspiration C) the ready conduction of heat in the soil D) the high specific heat of the soil E) the low oxygen content of the subsoil
D
The process of aerobic respiration is a significant source of which of the following gases? A) methane B) oxygen C) nitrogen D) carbon dioxide E) ammonia
D
The water potential at the leaf surfaces expressed in kPa is most likely to be ___________ A) -10 B) 33 C) -33 D) -500 E) -31,000
D
Two soil samples, A & B, at different soil moisture levels are placed in contact with each other. Water will more likely move from soil A to soil B if their water potentials, expressed in kPa, are: A) A = -5; B = +5 B) A = -5; B = -5 C) A = -20; B = -10 D) A = -30; B = -40 E) A = -100; B = -50
D
Where high-value crops or individual ornamental shrubs are to be grown and water is expensive, the most efficient type of irrigation to use would be ___________. A) center pivot B) basin flooding C) furrow D) drip or trickle
D
Which of the following expressions in kPa is most apt to characterize the gravitational potential of a clay loam surface soil? A) -5 B) -30 C) 0 D) +5 E) -3100
D
Which of the following processes are most apt to encourage good soil aeration? A) root respiration B) organic matter decomposition C) diffusion of oxygen from the soil to the atmosphere D) creation of more macropores E) reaction of oxygen with organic matter
D