Quiz 5
Which of the following expressions in kPa is most apt to characterize the gravitational potential of a clay loam surface soil? Select one: A. -5 B. -30 C. +5 D. -3100 E. 0
+5
At which of the following soil moisture potentials (expressed as kPa) is the soil water held most tightly? Select one: A. -3100 B. 0 C. +5 D. -1500 E. -31
-3100
At which of the following soil moisture potentials (expressed as kPa) is the waters' energy level lowest? Select one: A. -3100 B. +5 C. -31 D. -1500 E. 0
-3100
The water potential at the leaf surfaces expressed in kPa is most likely to be ________. Select one: A. -500 B. 33 C. -33 D. -31,000 E. -10
-500
The transpiration ratio of a native meadow is 550 kg per kg of dry matter produced. If 4 Mg of dry matter is produced on a hectare of land, how many centimeters of water will be required (rounded to the nearest cm)? Select one: A. 22 B. 46 C. 220 D. 14 E. not possible to calculate
22
Capillary movement is made possible by the processes of cohesion, and has little to do with adhesion. Select one: True False
False
Coarse-textured soils are high in sand content, easy to plow when dry, and have the highest water holding capacity of any soil at field capacity. Select one: True False
False
Mulches and crop residues affect soil water by increasing evapotranspiration. Select one: True False
False
Relative to core-aeration, spike-aeration is the preferred method of improving gaseous exchange between the soil and the atmosphere. Select one: True False
False
Soil water potential is the sum of the forces of gravity, adhesion and cohesion. It has little to do with the presence or absence of salts. Select one: True False
False
The property of cohesion in water stems from the attraction of water molecules for soil solids. Select one: True False
False
The tenacity with which water is held in soils is directly related to the soil moisture content, the higher the moisture level the greater the attraction of the water to the soil. Select one: True False
False
The water potential in soils is generally considered lower than that in the atmosphere. Select one: True False
False
There is a net movement of clouds from land areas to the ocean areas in the hydrologic cycle. Select one: True False
False
Vapor loss from a south-facing slope in Australia would likely be higher than from a north-facing slope. Select one: True False
False
The following is the reduced form of the essential element depicted ________. Select one: A. SO42- B. CO2 C. NH4+ D. Fe3+ E. Mn4+
NH4+
A well aerated soil is characterized by a relative abundance of ________. Select one: A. NO3- ions B. NH4+ ions C. methane gas D. micropores E. Fe2+ ions
NO3- Ions
The likelihood of polluting groundwater with pesticides and plant nutrients is enhanced by ________. Select one: A. the presence of macropores in the soil B. the use of tillage to control weeds C. conventional tillage as a choice compared with conservation tillage D. light tillage of the upper centimeter or so of soil E. the production of oats rather than wheat
The presence of micropores in the soil
Which of the following is not true with respect to the hydrologic cycle? Select one: A. Some 78% of the total precipitation falls onto the oceans. B. The average residence time of water in clouds is about 10 days. C. More than 85% of the water evaporated from the earth's surface comes from oceans. D. There is a net migration of some 40,000 km3 of water in clouds from the land area to the ocean areas. E. About one third of the readily accessible water in the hydrologic cycle is in the soil.
There is a net migration of some 40,000 km3 of water in clouds from the land area to the ocean areas.
Early snowfall that arrives before the cold winter weather has frozen the soil generally increases the penetration of water into the soil. Select one: True False
True
Evapotranspiration includes vapor losses both from the soil surface and from the leaves of plants. Select one: True False
True
Soil air usually has a higher carbon dioxide content than the air in the atmosphere. Select one: True False
True
The effect of soil organic matter on the amount of water available to plants is due to organic matter influence on total soil porosity as well as to the water-supplying power of the soil organic matter. Select one: True False
True
The leaf area index significantly affects the solar radiation reaching the soil surface. Select one: True False
True
The osmotic potential is dependent upon the presence of salts and other solutes in the soil. Select one: True False
True
The polarity of water helps account for the attraction of water molecules for each other. Select one: True False
True
The pollution of ground water is often increased by the presence of macropores in soils. Select one: True False
True
Two soil samples, A and 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 ________. Select one: A. A = -20; B = -10 B. A = -30; B = -40 C. A = -100; B = -50 D. A = -5; B = -5 E. A = -5; B = +5
A=-30; B=-40
Plant roots obtain access to soil water in which of the following ways? Select one: A. Water vapor moves from the wet soil areas to the root surfaces. B. Roots extend into moist soil area. C. The roots contract and leave room in the pores for the water to move in. D. Water flows to the roots by capillarity. E. both B and D
B and D
Which of the following locations in the United States would have the highest evaporation (E) from the soil surface in July? Select one: A. a bare, unirrigated dry land soil in Colorado B. an unirrigated soil in South Carolina growing cotton C. a corn field in New York D. a forest woodland in Illinois E. a furrow-irrigated cotton field in Arizona
a furrow-irrigated cotton field in Arizona
The osmotic potential would likely be lowest in soils of which of the following orders? Select one: A. Spodosols B. Histosols C. Aridisols D. Oxisols E. Ultisols
aridisols
Which of the following processes are most apt to encourage good soil aeration? Select one: A. creation of more macropores B. root respiration C. organic matter decomposition D. diffusion of oxygen from the soil to the atmosphere E. reaction of oxygen with organic matter
Creation of more macropores
Which of the following would you expect to have the highest leaf area index? Select one: A. corn, knee high B. corn three weeks after planting C. alfalfa just before harvest D. bare fallowed area E. either B or C (equal)
bare fallowed area
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? Select one: A. requires "destructive sampling" for each measurement B. good to turn on automatic irrigation at -5.0 kPa C. used to turn on irrigation when soil moisture potential reaches -20.0 kPa D. gives same reading for loamy sand and silt loam if both contained 15% moisture E. both A and D
both A and D
The process of aerobic respiration is a significant source of which of the following gases? Select one: A. oxygen B. nitrogen C. ammonia D. carbon dioxide E. methane
carbon dioxide
Which of the following sources of water have the shortest average residence time? Select one: A. soil moisture B. clouds C. oceans and ice caps D. groundwater
clouds
A greenhouse manager complained of stunted plants when soil beds stayed wet for long periods of time. To alleviate the problem you would recommend increasing the micropore percentage. Select one: True False
false
Although the total soil water content of a clay soil is about the same as a nearby well-structured silt loam, the clay will likely provide more available water to plants because of its higher volume of small pores. Select one: True False
false
At the soil moisture status "air dry," water can easily be extracted by plants. Select one: True False
false
In saturated soils, the microbially controlled chemical reduction of ferric iron (Fe3+) to ferrous iron (Fe2+) has little impact on the color of the soil. Select one: True False
false
Sprinkle irrigation is generally more efficient in the use of water than drip irrigation, especially for high valued crops. Select one: True False
false
Which of the following statements concerning applications or capabilities of soil moisture measuring devices is (are) true for the tensiometer? Select one: 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
good to turn on automatic irrigation at -50 kPa
Which of the following means of estimating soil water levels gives a direct measurement of the water content? Select one: A. gypsum blocks B. pressure membrane C. neutron scattering D. tensiometer E. gravimetric determinations
gravimetric determinations
In which of the following "forms" of soil water are pesticides, excess plant nutrients and waste chemicals most apt to move through soils? Select one: A. capillary B. available C. unsaturated D. hygroscopic E. gravitational
gravitational
In which of the following "forms" of soil water are pesticides, excess plant nutrients and waste chemicals most apt to move through soils? Select one: A. unsaturated B. gravitational C. available D. capillary E. hygroscopic
gravitational
Soils 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 O.M. soils? Select one: A. higher clay content B. higher capacity of the O.M. to hold water tightly C. higher field capacity D. lower permanent wilting percentage E. larger micro pore space
higher field capacity
A wildlife biologist in South Africa notes that the soils on south-facing slopes are wetter and deeper than those on north-facing slopes, and therefore support more wildlife. What likely accounts for this difference? Select one: A. sandier soils on the north slopes B. more solar radiation on the south slopes C. higher soil temperatures on the north slopes D. more rapid plant growth on the south slopes E. differences in rainfall from one area to another
higher soil temperatures on the north slopes
Which of the following is (are) considered necessary features for an area to be delineated as a wetland? Select one: A. hydric soils B. aquatic vegetation C. shallow standing water D. organic soils E. all of the above
hydric soils
The water content in a soil is known to be .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 ________. Select one: A. 20 B. 0 C. -5 D. -20 E. impossible to calculate with the data given
impossible to calculate with the data given
Capillarity in soils ________. Select one: A. is enhanced by the symmetrical nature of the water molecule B. involves both adhesion and cohesion C. does not account for unsaturated water movement in soils D. is independent of the matric potential in soils E. is not involved in the process of water uptake from soils
involves both adhesion and cohesion
Groundwater ________. Select one: A. moves laterally but not vertically below the soil profile B. is a source of water above the vadose zone in a soil C. moves downward in the vadose zone through the capillary fringe D. is found mostly in shallow layers just below the argillic E. is a major source of water for irrigation in the United States
is a major source of water for irrigation in the United States
The following are characteristics of a water molecule. Select one: A. It has a positive and a negative side. B. It is attracted to surfaces with negative but not positive charges. C. The H to O to H angle is approximately 90∘C. D. The two H atoms are on diametrically opposite ends of the molecule. E. It is held in soils by adhesion but not adsorption.
it has a positive and a negative side
Land drainage is beneficial because ________. Select one: A. it increases the water-to-air ratio in the soil pores B. it slows down the rate of soil warming in the spring C. it increases the availability of iron and manganese in acid soils D. it increases the alternate of expansion and contraction due to freezing and thawing of soils E. it increases the depth of root penetration in the soil
it increases the depth of root penetration in the soil
Compared to upland soils, wetland soils would be characterized by an abundance of ________. Select one: A. NO3- B. Fe3+ C. methane D. CO2 E. SO42-
methane
Which of the following is not a major factor in determining the soil aeration status? Select one: A. redox potential B. carbon dioxide C. nitrogen gas D. oxygen E. volume of macropores
nitrogen gas
Which of the following will increase the evaporation (E) from the soil surface? Select one: A. stubble mulch farming B. plastic mulch C. the use of no-till culture D. adding straw mulch to the soil surface E. none of the above
none of the above
The matric potential of soil water is ________. Select one: A. is generally higher than that of pure water outside the soil B. is lower in a sandy soil with 20 percent soil water than in a clay soil with same percentage of moisture C. not influenced appreciably by the force of gravity D. is little affected by soil solids E. influenced greatly by the content of salts in the soil
not influences appreciably by the force of gravity
Unsaturated water flow ________. Select one: A. is driven primarily by the force of gravity B. is slower on sands than on clays if the soil moisture content is high C. is faster than saturated flow D. is stimulated by the osmotic potential E. occurs on soils that are at field capacity
occurs on soils that are at field capacity
Of the various types of drain systems, open ditch systems are most practical and economical for use on ________. Select one: A. Vertisols B. soils with a deep water table C. soils which do not freeze during the winter D. poorly drained soils with sandy profiles E. clay soils with poor drainage
poorly drained soils with sandy profiles
Of the various types of drain systems, open ditch systems are most practical and economical for use on ________. Select one: A. clay soils with poor drainage B. Vertisols C. soils which do not freeze during the winter D. poorly drained soils with sandy profiles E. soils with a deep water table
poorly drained soils with sandy profiles
Which of the following actions would best assure good aeration in a soil? Select one: A. remove excess water B. use cover crops, especially legumes C. use a plastic mulch D. increase the soil temperature E. add organic residues
remove excess water
The most common form of on-site waste water treatment for homes not hooked up to sewer lines is the ________. Select one: A. active composting method B. septic tank and drain field C. chemical "flush" system D. electrical induction sterilization E. soil enrichment process
septic tank and drain field
The redox potential is a measure of ________. Select one: A. the ferric ion content B. the tendency of a substance to accept or donate electrons C. carbon dioxide content D. molecular oxygen content E. the balance between hydrogen and hydroxyl ions in solution.
the tendency of a substance to accept or donate electrons
Drainage pipe comes in 200 ft long rolls. The number of rolls needed to construct a uniform buried drainage system for a nearly level 20 hectare field will depend primarily on ________. Select one: A. the texture and structure of the soil B. the saturated moisture potential of the soil C. the slope of the drain lines D. rate of capillary movement in the soil E. the annual rainfall
the texture and structure of the soil
Which of the following will not increase the efficiency of water use by plants in an irrigation system? Select one: A. the use of drip irrigation for fruit trees B. the use of concrete-lined delivery ditches C. the use of flood irrigation for forage crops D. the use of crop residues to reduce evaporation E. the use of herbicides to control weeds
the use of flood irrigation for forage crops
If you dug a deep hole in your back yard and water started to seep into the hole it would fill the hole up to ________. Select one: A. the liquid limit B. the water table C. field capacity D. the percolation rate E. the infiltration rate
the water table
Because of their greater surface area per unit of soil mass, silt loams soils generally have a greater capacity than loamy sand soils to adsorb water, adsorb gases, release nutrients by mineral weathering and support bacterial growth. Select one: True False
true
Drip irrigation would more likely be used in the production of apples or peaches than in the production of wheat. Select one: True False
true
Evaporation from a south-facing slope in Russia would likely be higher than from a north-facing slope. Select one: True False
true
The matric potential is due to the attraction of water molecules to soil solid surfaces. Select one: True False
true
Total soil water potential is a function of gravitational potential, osmotic potential and matric potential. Select one: True False
true
In which of the following situations would you expect downward movement of soil water through the profile to be most rapid? Select one: A. sandy loam in upper layers with a clay band underneath B. uniformly textured sandy loam profile C. sandy loam in upper layers with a layer of coarse gravel underneath D. silt loam in upper layers underlain by a sandy layer E. clay texture throughout the profile
uniformly textured sandy loam profile
Which of the following statements concerning applications or capabilities of soil moisture measuring devices is (are) true for the electrical resistance block? Select one: 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
used to turn on irrigation when soil moisture potential reaches -200 kP
Which of the following best characterizes the field capacity of a soil? Select one: A. the total capillary water in a soil B. maximum capacity of a soil to hold water C. soil with water potential of -1500 kPa D. a wetted soil prior to the removal of the gravitational water E. water content of a soil with water potential of about -10 kPa
water content of a soil with water potential of about -10 kPa
Which of the following statements concerning applications or capabilities of soil moisture measuring devices is (are) true for the neutron probe? Select one: 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
would give the same reading for both a loamy sand and a silt loam if both contained 15% moisture
Urban development of land under natural vegetation or agriculture usually greatly ________ soil infiltration capacity and therefore greatly increases ________. Select one: A. increases; groundwater recharge. B. decreases; groundwater recharge. C. increases; stream bank erosion. D. decreases; stream bank erosion.
decreases; stream bank erosion
The bulk of gaseous interchange in soils takes place by ________. Select one: A. diffusion B. mass flow C. respiration D. partial pressure of N2 E. dissolution in water
diffusion
The expression, P - ET -SS estimates the ________ a watershed. Select one: A. discharge volume from B. evaporation from C. soil water content of D. interception in
discharge volume from
Which of the following irrigation systems produces the most biomass per unit of water applied? Select one: A. furrow irrigation B. flood irrigation C. furrow-dike irrigation D. sprinkle irrigation E. drip irrigation
drip irrigation
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 ________. Select one: A. center pivot B. drip or trickle C. furrow D. basin flooding
drip or trickle
