AGRI 1050/1051 Soil Science Walters State Fall 2020 Midterm Study Guide

horizons

The layers of contrasting material found when one digs a hole in the ground

Soils of good tilth and high productivity are usually characterized by stable aggregation and a high percentage of macropores. 1) True 2) False

True

The process of aerobic respiration is a significant source of which of the following gases? 1) methane 2) oxygen 3) nitrogen 4) carbon dioxide 5) ammonia

carbon dioxide

Igneous, sedimentary, and metamorphic are three _________. 1) types of rocks 2) basic classes of soils 3) master horizon names 4) forms of minerals 5) processes of weathering

1) types of rocks

Texture describes the ____ of particles in a soil. 1) sizes 2) colors 3) arrangement 4) mineralogical makeup 5) roughness

1) sizes

Compared to a similar soil under native vegetation, a soil with a long history of conventionally tilled cropping would have less micropore space. 1) True 2) False

False

Flocculation is the process by which certain chemicals in the soil stabilize large soil aggregates. 1) True 2) False

False

For most soils, plowing and harrowing every year improves soil tilth in the long run. 1) True 2) False

False

B horizon

Subsoil is generally equivalent to which soil horizon?

texture

The amount of different sizes of mineral particles in a soil defines the soil ________.

Which of the following will not increase the efficiency of water use by plants in an irrigation system? 1) The use of concrete-lined delivery ditches 2) The use of flood irrigation for forage crops 3) The use of drip irrigation for fruit trees 4) The use of crop residues to reduce evaporation 5) The use of herbicides to control weeds

The use of flood irrigation for forage crops

contains organic compounds, contains mineral nutrients, and it is restrained in its flow by attraction to particle surfaces

The water in the soil typically differs from pure water because the soil water ________.

Fungal hyphae play an important role in stabilizing surface soil aggregates. 1) True 2) False

True

If the CO2 content of soil air is 3.5%, it is 100 times higher than that of the atmosphere. 1) True 2) False

True

More than ninety-eight percent of the earth's water does not take part in the annual cycling known as the hydrologic cycle. 1) True 2) False

True

Subsoiling is a primitive deep tillage technique that results in extremely high subsoil bulk density. 1) True 2) False

False

A well aerated soil is characterized by a relative abundance of _____. 1) micropores 2) Fe2+ions 3) NH4+ ions 4) NO3- ions 5) methane gas

NO3- ions

The polarity of water helps account for the attraction of water molecules for each other. 1) True 2) False

True

The pollution of ground water is often increased by the presence of macropores in soils. 1) True 2) False

True

The redox potential is a measure of the tendency of a substance to accept or donate electrons. 1) True 2) False

True

The water potential at the field capacity for most soils is in the range of -10 to -30 kPa. 1) True 2) False

True

Tillage when the soil is too wet is likely to increase the soil bulk density. 1) True 2) False

True

Ultisols

Typical well drained, well developed soil in Northeast Tennessee will most likely be classified as a:

vertisols

high swelling capacity clays

The most important management factors influencing soil aeration in well-drained soils are those that determine the volume of the soil's macropores. 1) True 2) False

True

The partial pressure of CO2 in the soil pores is higher than the partial pressure of this gas in the atmosphere. 1) True 2) False

True

Alluvial fans are usually characterized by ______ soils. 1) sandy and gravelly 2) clay textured 3) poorly drained 4) nearly level

1) sandy and gravelly

The following is the reduced form of the essential element depicted 1) NH4+ 2) Fe3+ 3) CO2 4) SO42- 5) Mn4+

NH4+

A friable soil is usually more likely to be indurated. 1) True 2) False

False

The average residence time for water in clouds over the ocean is about one year. 1) True 2) False

False

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. 1) True 2) False

False

The great bulk of gaseous interchange between the soil pores and the atmosphere occurs by mass flow of the concerned gases. 1) True 2) False

False

The matric potential is due to the attraction of water molecules to soil solid surfaces. 1) True 2) False

True

When preparing a surface soil seedbed, the soil should generally be in the loosest, least dense soil condition in the row where the seed is placed. 1) True 2) False

True

Which color would be typical of a well drained, low-organic matter sandy surface soil? 1) 10YR5/8 2) 7.5YR6/2 3) 2.5YR6/1 4) 7.5YR2/2 5) 10YR8/4

1) 10YR5/8

Organic matter accumulation is most pronounced in the ____. 1) O horizon 2) A horizon 3) E horizon 4) B horizon 5) C horizon

1) O horizon

If you wanted to find a soil where physical weathering dominated over chemical breakdown you would be most apt to find it in ______. 1) a desert region of Arizona 2) a humid region in Brazil 3) the hill lands of Georgia 4) a lacustrine deposit in Minnesota 5) a coastal plain area of Delaware

1) a desert region of Arizona

In which of the following "forms" of soil water are pesticides, excess plant nutrients and waste chemicals most apt to move through soils? 1) gravitational 2) unsaturated 3) available 4) hygroscopic 5) capillary

1) gravitational

Capillarity in soils _____. 1) involves both adhesion and cohesion 2) is enhanced by the symmetrical nature of the water molecule 3) is independent of the matric potential in soils 4) is not involved in the process of water uptake from soils 5) does not account for unsaturated water movement in soils

1) involves both adhesion and cohesion

Practices that add organic matter and reduce tillage can be expected to most significantly increase the _____ in a soil. 1) macropores 2) total porosity 3) bulk density 4) fineness of texture

1) macropores

In which of the following situations would you expect downward movement of soil water through the profile to be most rapid? 1) uniformly textured sandy loam profile 2) sandy loam in upper layers with a clay band underneath 3) sandy loam in upper layers with a layer of coarse gravel underneath 4) clay texture throughout the profile 5) silt loam in upper layers underlain by a sandy layer

1) uniformly textured sandy loam profile

Silicate clay accumulation is most common in the ____. 1) A horizon 2) B horizon 3) C horizon 4) O Horizon 5) E horizon

2) B horizon

Which of the following is not true with respect to the hydrologic cycle? 1) More than 85% of the water evaporated from the earth's surface comes from oceans. 2) There is a net migration of some 40,000 km3 of water in clouds from the land area to the ocean areas. 3) The average residence time of water in clouds is about 10 days. 4) Some 78% of the total precipitation falls onto the oceans. 5) About one third of the readily accessible water in the hydrologic cycle is in the soil.

2) There is a net migration of some 40,000 km3 of water in clouds from the land area to the ocean areas.

The presence of rocks such as shale and sandstone indicate the existence of _______. 1) a high water table 2) ancient seas 3) old mountain ranges 4) iron-rich minerals 5) highly weathered soils

2) ancient seas

The mixed angular gravel, rock, and soil found at the foot of a slope is typical of what type parent material? 1) eolian 2) colluvial 3) fluvial 4) glacial 5) lacustrine

2) colluvial

Dull gray colors are characterized by _____. 1) gray hues 2) low chromas 3) high color values 4) low color values 5) mixed hues

2) low chromas

Residual parent materials are best described as __________. 1) materials formed under organic residues. 2) materials formed by weathering of rocks and minerals in place. 3) materials transported from one location to another by water, ice or wind. 4) materials more dominant in Iowa than in the Southern United States. 5) upland materials formed with relatively little chemical weathering.

2) materials formed by weathering of rocks and minerals in place.

The matric potential of soil water is _____. 1) influenced greatly by the content of salts in the soil 2) not influenced appreciably by the force of gravity 3) is generally higher than that of pure water outside the soil 4) is little affected by soil solids 5) is lower in a sandy soil with 20 percent soil water than in a clay soil with same percentage of moisture

2) not influenced appreciably by the force of gravity

The percentages of which soil components represent the minimum information necessary in order to determine the textural class of a soil? 1) gravel and sand 2) silt and sand 3) clay and organic matter 4) clay, water and air 5) sand, silt and clay

2) silt and sand

Which of the following best characterizes the field capacity of a soil? 1) maximum capacity of a soil to hold water 2) water content of a soil with water potential of about -10 kPa 3) the total capillary water in a soil 4) a wetted soil prior to the removal of the gravitational water 5) soil with water potential of -1500 kPa

2) water content of a soil with water potential of about -10 kPa

The following are true characteristics of a water molecule. 1) The H to O to H angle is approximately 90o C. 2) The two H atoms are on diametrically opposite ends of the molecule. 3) It has a positive and a negative side. 4) It is attracted to surfaces with negative but not positive charges. 5) It is held in soils by adhesion but not adsorption.

3) It has a positive and a negative side.

Wind blown silt sized materials is known as: 1) Silt 2) Glacial 3) Loess 4) Lacustrine 5) Residual

3) Loess

If a dry soil high in certain types of ____ is moistened, it is likely to swell up with enough force to crack pavements and building foundations. 1) humus 2) iron 3) clay 4) silt 5) any of the above

3) clay

Which of the following means of estimating soil water levels gives a direct measurement of the water content? 1) gypsum blocks 2) neutron scattering 3) gravimetric determinations 4) tensiometer 5) pressure membrane

3) gravimetric determinations

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 1) larger micro pore space 2) lower permanent wilting percentage 3) higher field capacity 4) higher capacity of the O.M. to hold water tightly 5) higher clay content

3) higher field capacity

Mechanical weathering processes result in: 1) the decomposition of primary minerals 2) the hydrolysis of minerals through frost action 3) the disintegration of rocks due to differential expansion of minerals 4) the oxidation of iron and manganese compounds

3) the disintegration of rocks due to differential expansion of minerals

Soil colors are scientifically described by ____ color designations such as 10YR3/4. 1) USDA 2) wavelength 3) Parson's 4) Munsell 5) structural

4) Munsell

Colloidal properties are exhibited by the ___ fraction of soils. 1) gravel 2) sand 3) silt 4) clay

4) clay

Secondary minerals are most prominent in the fraction of soils. 1) organic 2) sand 3) silt 4) clay

4) clay

Using a textural triangle chart, it can be determined that a soil with 45% sand and 20% clay belongs to the ___textural class. 1) sandy loam 2) loamy sand 3) sandy clay loam 4) loam 5) sandy clay

4) loam

A landscaping contractor wants to change the texture of a silt loam soil to meet the specifications for a loam. S/he would most likely do so by adding ______ to the soil and mixing it well. 1) humus 2) compost 3) clay 4) sand 5) either A or B

4) sand

Soil tilth refers to _____. 1) the bearing strength of a soil under a given downward force 2) the moisture content at which a soil is best suited for tillage 3) ratio of bulk density to particle density 4) the physical suitability of a soil for plant growth 5) micro-aggregates produced as a by-product of tillage True or False Questions

4) the physical suitability of a soil for plant growth

Which of the following is not considered one of the five major factors influencing soil formation? 1) native parent materials 2) living organisms 3) climate 4) valence state 5) topography

4) valence state

Because of their greater surface area per unit of soil mass, silt loams soils generally have a greater capacity than loamy sand soils to ___. 1) adsorb water 2) adsorb gases 3) release nutrients by mineral weathering 4) support bacterial growth 5) all of the above

5) all of the above

Which of the following practices is(are) useful in stabilizing surface soil structure? 1) use of organic mulches 2) use of green manure crops 3) growing grass sod 4) minimizing tillage 5) all of the above

5) all of the above

The transformation of gneiss into mica, quartz, and feldspar crystals is an example of: 1) physical weathering 2) chemical weathering 3) disintegration 4) hydrolysis 5) both A and C

5) both A and C

Plant roots obtain access to soil water in which of the following ways? 1) The roots contract and leave room in the pores for the water to move in. 2) Roots extend into moist soil area. 3) Water vapor moves from the wet soil areas to the root surfaces. 4) Water flows to the roots by capillarity. 5) both B and D

5) both B and D

Glacial till is a term used to describe parent materials that: 1) were transported by water gushing from glacial fronts. 2) were laid down in the bottom of former glacial lakes. 3) were transported by high winds during glacial periods. 4) are sorted by rapidly flowing melt waters. 5) contain a heterogeneous mixture of mineral debris dropped by receding glaciers.

5) contain a heterogeneous mixture of mineral debris dropped by receding glaciers.

The element most often involved in oxidation reactions as minerals weather is _____. 1) copper 2) silicon 3) aluminum 4) magnesium 5) iron

5) iron

Brown and red colors in subsurface horizons are caused by __ in the soil. 1) manganese 2) aluminum oxides 3) organic matter 4) clay 5) iron oxides

5) iron oxides

Unsaturated water flow _____________. 1) is faster than saturated flow 2) is driven primarily by the force of gravity 3) is stimulated by the osmotic potential 4) is slower on sands than on clays if the soil moisture content is high 5) occurs on soils that are at field capacity

5) occurs on soils that are at field capacity

Which of the following is NOT a textural class name? 1) sand 2) silt 3) loam 4) clay 5) sandy silt

5) sandy silt

In a field experiment you noted that 300 tons of water was transpired to produce 1 ton of corn (dry weight). If alfalfa had been grown in the same field instead of corn, which of the following would most likely have been the amount of water transpired? 1) 500 tons 2) 300 tons 3) 275 tons 4) 250 tons 5) depends on the climate in the area of the experiment

500 tons

Entisols

In which soil orders would recent alluvium most likely be a common parent material?

Which of the following sources of water have the shortest average residence time? 1) Soil moisture 2) Clouds. 3) Oceans and ice caps 4) groundwater

Clouds

The following is the reduced form of the essential element depicted: A. NH4+ B. FE3+ C. CO2 D. SO42- E. Mn4+

E: Mn4+

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. 1) True 2) False

False

Hydraulic redistribution or hydraulic lift dries out shallower soils during dry periods, allowing trees to take advantage of water deeper in the soil profiles. 1) True 2) False

False

In acid soils you would be concerned if the redox potential was low since it could mean a deficiency of some plant nutrients such as iron and manganese. 1) True 2) False

False

Light colored surface soils are likely to be warmer than dark-colored surface soils if soil moisture and other conditions are the same. 1) True 2) False

False

Plant roots gain access to soil water primarily by the growth of the roots into moist soil. 1) True 2) False

False

Recent research with annual crops such as wheat, sunflower and sorghum in the Great Plains region suggests that, compared to continuous cropping, soil quality, crop productivity and farm profitability are likely to be greater when crops are grown in a field only every second year with the soil kept free of weeds in the non-crop year by repeated cultivation of herbicide application. 1) True 2) False

False

Reduced forms of iron and manganese along with soil organic matter largely control the color of well-drained soils. 1) True 2) False

False

Respiration by plant and animal cells along with photosynthesis releases oxygen and consumes carbon dioxide. 1) True 2) False

False

Some 60 percent of the water that is actively involved in the hydrologic cycle worldwide is found in soils. 1) True 2) False

False

Some two-thirds of the solar energy reaching the earth is absorbed by water on or near the earth's surface. 1) True 2) False

False

Sprinkle irrigation is generally more efficient in the use of water than drip irrigation, especially for high valued crops. 1) True 2) False

False

The hydrogen end of a water molecule is attracted to positively charged cations such as Na+ and Ca2+. 1) True 2) False

False

The property of cohesion in water stems from the attraction of water molecules for soil solids. 1) True 2) 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. 1) True 2) False

False

There is a net movement of clouds from land areas to the ocean areas in the hydrologic cycle. 1) True 2) False

False

increase the soil's water holding capacity

Increasing the organic matter content of a soil is likely to _____.

histosols

If the soils are to be used for crop production, for which soil order would land drainage be most critical

soil solution

Most of the different nutrients essential for growth are supplied to plants directly from the ______.

Russia

Soil scientists from which country first conceived the idea that soils were natural bodies?

A horizon

Topsoil is generally equivalent to which soil horizon?

An abundance of macropores in soils helps assure an abundance of oxygen in the soil. 1) True 2) False

True

Anaerobic conditions commonly prevail in liberally watered flower pots with mineral soil as the growing medium even though the containers have holes for drainage in the bottom of the pot. 1) True 2) False

True

Capillary movement is made possible by the processes of cohesion and adhesion. 1) True 2) False

True

Corn plants are generally more efficient in the use of water than is alfalfa. True or False?

True

Drip irrigation would more likely be used in the production of apples or peaches than in the production of wheat. 1) True 2) False

True

Early snowfall that arrives before the cold winter weather has frozen the soil generally increases the penetration of water into the soil. 1) True 2) False

True

Eutrophication is enhanced by the presence of pesticides in the water draining from agricultural soils. True or False?

True

1.0

What pH value has the most acid condition?

Which of the following locations in the United States would have the highest evaporation (E) from the soil surface in July? 1) a bare, unirrigated dry land soil in Colorado 2) an unirrigated soil in South Carolina growing cotton 3) a furrow-irrigated cotton field in Arizona 4) a forest woodland in Illinois 5) a corn field in New York

a furrow-irrigated cotton field in Arizona

argillic horizons

accumulation of silicate clays

Which of the following would you expect to have the highest leaf area index? 1) Bare fallowed area 2) Corn three weeks after planting 3) Corn, knee high 4) Alfalfa just before harvest 5) Either B or C (equal)

alfalfa before harvest

Plant transpiration efficiency at a given location is markedly influenced by _____. 1) organic residue cover on the soil 2) tillage practices used 3) fertilization practices used 4) the plant species being grown 5) both C and D

both C and D

spodosols

commonly sandy in texture, quite acidic and develop primarily under coniferous trees in cool to cold climates

Which of the following processes are most apt to encourage good soil aeration? 1) root respiration 2) organic matter decomposition 3) diffusion of oxygen from the soil to the atmosphere 4) creation of more macropores 5) reaction of oxygen with organic matter

creation of more macropores

Urban development of land under natural vegetation or agriculture usually greatly _____ soil infiltration capacity and therefore greatly increases _______. 1) decreases stream bank erosion. 2) increases stream bank erosion. 3) decreases groundwater recharge. 4) increases .groundwater recharge.

decreases stream bank erosion.

The bulk of gaseous interchange in soils takes place by _____. 1) mass flow 2) partial pressure of N2 3) diffusion 4) dissolution in water 5) respiration

diffusion

The expression, P - ET -SS estimates the ________ a watershed. 1) soil water contentof 2) discharge volumefrom 3) evaporation from 4) interception in

discharge volume from

Which of the following irrigation systems produces the most biomass per unit of water applied? 1) flood irrigation 2) furrow irrigation 3) drip irrigation 4) sprinkle irrigation 5) furrow-dike 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 ______. 1) center pivot 2) basin flooding 3) furrow 4) drip or trickle

drip or tickle

Cu (copper)

example of an essential plant nutrient

Land drainage is beneficial because _____. 1) it increases the alternate of expansion and contraction due to freezing and thawing of soils 2) it increases the water-to-air ratio in the soil pores 3) it slows down the rate of soil warming in the spring 4) it increases the depth of root penetration in the soil 5) it increases the availability of iron and manganese in acid soils

it increases the depth of root penetration in the soil

Compared to upland soils, wetland soils would be characterized by an abundance of _____. 1) methane 2) CO2 3) NO3- 4) SO42- 5) Fe3+

methane

Soil A has a redox potential of 400 mV, soil B -200 mV. Of the two soils, Soil A is more apt to be characterized by an abundance of _____. 1) Fe2+ ions 2) Mn2+ ions 3) H+ ions 4) S2- ions 5) molecular oxygen

molecular oxygen

Which of the following is not a major factor in determining the soil aeration status? 1) redox potential 2) volume of macropores 3) nitrogen gas 4) carbon dioxide 5) oxygen

nitrogen gas

Which of the following will increase the evaporation (E) from the soil surface? 1) adding straw mulch to the soil surface 2) the use of no-till culture 3) stubble mulch farming 4) plastic mulch 5) none of the above

none of the above

7.0

pH value with a neutral condition

Gelisols

permafrost soils

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 temperature? 1) no-till system 2) conventional moldboard plow system 3) ridge-till system 4) heavy organic residues 5) heavy chemical fertilization

ridge-till system

The most common form of on-site waste water treatment for homes not hooked up to sewer lines is the _______. 1) active composting method 2) septic tank and drain field 3) chemical "flush" system 4) electrical induction sterilization 5) soil enrichment process

septic tank and drain field

three-dimensional unit that embodies the primary characteristics of an individual soil

soil pedon

The likelihood of polluting groundwater with pesticides and plant nutrients is enhanced by _____. 1) the presence of macropores in the soil 2) light tillage of the upper centimeter or so of soil 3) the use of tillage to control weeds 4) the production of oats rather than wheat 5) conventional tillage as a choice compared with conservation tillage

the presence of macropores in the soil

The redox potential is a measure of _____. 1) molecular oxygen content 2) the tendency of a substance to accept or donate electrons 3) carbon dioxide content 4) the ferric ion content 5) the balance between hydrogen and hydroxyl ions in solution.

the tendency of a substance to accept or donate electrons