Title: EXAM 2 - (Chapters 7, 9, 10, 11, 12)
Course: MASTER-AGRI-1153-HB-Kern > Section: Chapter 12: Soil Organic Matter - Due February 17

Q: Which of the following is (are) considered necessary features for an area to be delineated as a wetland?
- hydric soils
- shallow standing water
- aquatic vegetation
- organic soils
- all choices are correct
A: all choices are correct
If right: Your answer is correct.
If wrong: Your answer is incorrect.

Q: A soil is said to be waterlogged or saturated when nearly all of the soil pores are filled with water.
- True
- False
A: True

Q: Respiration by the roots of upland plants usually depletes the O2 in the soil just outside of the root.
- True
- False
A: True

Q: 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 _____.
- the expansion of water when it freezes
- the wetting and drying of swelling-type clays
- pressure from upward movement of water from lower horizons
- the breaking down of soil aggregates due to freezing and thawing
- the hydration of adsorbed cations on the soil colloids
A: the expansion of water when it freezes
If right: Your answer is correct.
If wrong: Your answer is incorrect.

Q: The redox potential is a measure of _____.
- molecular oxygen content
- the tendency of a substance to accept or donate electrons
- carbon dioxide content
- the ferric ion content
- the balance between hydrogen and hydroxyl ions in solution.
A: the tendency of a substance to accept or donate electrons
If right: Your answer is correct.
If wrong: Your answer is incorrect.

Q: ___________ soils are saturated long enough during periods of enough biological activity to cause anaerobic conditions to occur and redoximorphic features and other hydric soil indicators to form.
- Organic
- Sodic
- Hydric
- Alkaline
- Acidic
A: Hydric
If right: Your answer is correct.
If wrong: Your answer is incorrect.

Q: The _________________ of a soil is determined by three primary factors:  a) solar radiation,  b) the specific heat of the soil, and  c) energy needed to evaporate soil water.

Q: The drainage of certain wetlands has resulted in extreme soil acidity. This is due primarily to which of the following processes that take place when the soil is drained?
- oxidation of organic materials to produce organic acids
- reduction of iron to low valent states that stimulate acidity
- release of nitric acid due to oxidation of nitrogen compounds  _
- high redox potential characteristic of aerated soils
- oxidation of sulfur-bearing minerals that produces sulfuric acid
A: oxidation of sulfur-bearing minerals that produces sulfuric acid
If right: Your answer is correct.
If wrong: Your answer is incorrect.

Q: If you want to increase the pH of a soil from 5.5 to 7.0, which of the following would you use?
- burned limestone
- sulfur
- saw dust
- bat guano
A: burned limestone
If right: Your answer is correct.
If wrong: Your answer is incorrect.

Q: Sulfur can be used to increase soil acidity and to reduce alkalinity.
- True
- False
A: True

Q: Nitrogen fertilization is a significant cause of acidity in many cultivated soils.
- True
- False
A: True

Q: Alkalinity simply refers to pH levels above neutral (>7.0) and is not to be confused with alkali conditions which involve high levels of exchangeable sodium.
- True
- False
A: True

Q: ___________ tend to accumulate naturally in some soils of arid and semiarid regions because there is insufficient rainfall to flush them from the upper soil layers.
- Organic matter
- Gravel
- Salt
- Limestone
A: Salt
If right: Your answer is correct.
If wrong: Your answer is incorrect.

Q: Sodic soils have the sodium levels of saline-sodic soils without the moderating influences of the neutral salts.
- True
- False
A: False

Q: Which of the following human actions is most apt to result in a long term increase in soil pH?
- application of NH_4^- containing fertilizers
- application of farm manure
- irrigation with high sodium salt-containing waters
- emission of gases from automobiles
- application of unlimed sewage sludge
A: irrigation with high sodium salt-containing waters
If right: Your answer is correct.
If wrong: Your answer is incorrect.

Q: Phosphorus availability in acid soils is constrained by the presence of significant quantities of reactive ______.
- Iron
- Calcium
- Boron
- Nitrogen
A: Iron
If right: Your answer is correct.
If wrong: Your answer is incorrect.

Q: In strongly acid soils, Aluminum plays a very significant role.  The colloidal complex is dominated by Al^3+ ions and associated hydroxy-aluminum ions (e.g. Al(OH)^2+) complemented by a low level of adsorbed H^+ ions.  Much of the Al^3+ and H^+ is bound tightly in the organic matter and on clay crystal edges, and is not readily exchangeable.
- True
- False
A: True

Q: The total acidity in soils is the sum of the active, exchangeable (salt replaceable) and residual pools of soil acidity.
- True
- False
A: True

Q: The three forms of soil acidity suggest that a mechanism exists to resist rapid and uncontrolled drastic changes in the active pool of soil acidity.  This resistance is called ___________________.
- Buffering
- Trifecta
- Osmosis
- Anhydrous ammonia
A: Buffering
If right: Your answer is correct.
If wrong: Your answer is incorrect.

Q: Adding the proper amount of  _____________ to soil raises the pH of acidic soils.  It not only maintains the levels of exchangeable calcium and magnesium but also in so doing also provides a chemical and physical environment that encourages the growth of most common plants. Ground calcite (CaCO_3) and dolomite (CaCO_3 - MgCO_3) are the primary carbonate sources that are widely used around the world.
- Nitrogen
- Lime
- Sulfur
- Innoculant
A: Lime
If right: Your answer is correct.
If wrong: Your answer is incorrect.

Q: Normal alkaline soils are characterized by all but which one of the following?
- low levels of available iron
- high levels of molybdenum
- high levels of exchangeable sodium
- low levels of available manganese
- low levels of available boron
A: high levels of exchangeable sodium
If right: Your answer is correct.
If wrong: Your answer is incorrect.

Q: The cation exchange capacities of alkaline soils are generally higher than those of acid soils (Vertisols excepted).  Which of the following characteristics of alkaline soils most likely accounts for this high CEC?
- high humus content
- high content of hydrous oxides of iron and aluminum
- high exchangeable calcium
- high exchangeable sodium content
- high content of 2:1 type clays
A: high content of 2:1 type clays
If right: Your answer is correct.
If wrong: Your answer is incorrect.

Q: Normal alkaline soils often exhibit deficiencies of available iron and manganese.
- True
- False
A: True

Q: Saline soils are characteristic of arid and semiarid areas with poor internal drainage.
- True
- False
A: True

Q: Sulfuric acid is sometimes added to irrigation water to help in the reclamation of sodic soils.
- True
- False
A: True

Q: Conservation tillage can help reduce salt build up by reducing surface evaporation.
- True
- False
A: True

Q: Which of the following groups of organisms are responsible for greatest amount of organic matter decomposition in soils?
- macrofauna
- larvae
- mesophauna
- Microfauna
- microflora
A: microflora
If right: Your answer is correct.
If wrong: Your answer is incorrect.

Q: ____________  and ____________ are the two most important groups of microscopic animals living in soils that have both beneficial and negative effects on the soil and plant growth conditions.
- nematodes, protazoa
- earthworms, gophers
- moles, nematodes
- beetles, larvae
A: nematodes, protazoa
If right: Your answer is correct.
If wrong: Your answer is incorrect.

Q: Earthworms are encouraged by soils high in organic matter, lime, and with good drainage. Very acid and very sandy conditions, as well as extensive tillage, are detrimental to most earthworms.
- True
- False
A: True

Q: Like other ecosystems, soil ecosystems are characterized by ___________________ that include many species at each of the main trophic levels including primary producers, primary consumers (include herbivores and detritivores), secondary and tertiary consumers.  The diversity of soil organisms is an important factor of soil quality and ecosystem function.
- food webs
- biomass
- layers
- none of the above
A: food webs
If right: Your answer is correct.
If wrong: Your answer is incorrect.

Q: A healthy soil community is likely to minimize problems with plant ______________, which cause economic yield losses, through a complex set of ecological interactions, including microbial antagonisms, development of disease suppressive soils, and induced systemic resistance.
- fertilizers
- biomass
- Pathogens
- all of the answers are correct
A: Pathogens
If right: Your answer is correct.
If wrong: Your answer is incorrect.

Q: Soil microflora consists of algae, bacteria, fungi, and actinomycetes. Even though the microflora is much for numerous and diverse, the impact it makes on the soil ecosystem is enhance in many ways by the presence of _____________.
- fauna
- soil seed bank
- rhizosphere
- nitrogen
A: fauna
If right: Your answer is correct.
If wrong: Your answer is incorrect.

Q: Most anaerobic organisms in soils are ____________.
- macrofauna
- termites and ants
- earthworms
- Bacteria
A: Bacteria
If right: Your answer is correct.
If wrong: Your answer is incorrect.

Q: Carbon cycles from the atmosphere to plants to soil organic matter and back to the atmosphere.
- True
- False
A: True

Q: The oceans act as a buffer for atmospheric carbon dioxide by dissolving or releasing large quantities, but fossil fuel burning and soil organic matter depletion add more carbon to the atmosphere each year than the oceans take out, resulting in rising levels of carbon dioxide that are believed to be the main cause of ___________________.
- acid rain
- global warming
- nautical phasmidation
- 2, 4, 5 - T (agent orange)
A: global warming
If right: Your answer is correct.
If wrong: Your answer is incorrect.

Q: Soils with more than 20 to 30% organic matter (depending on clay content) are termed organic soils and are classified in the Histosols order in Soil taxonomy.
- True
- False
A: True

Q: ___________ mined from Histosols are commercially used for potting media and mulches. They are light weight, hold much water, and have a high nutrient holding capacity (though often low in nutrient as found).
- Organic matter
- Peats
- Fertilizers
- Soil colloids
A: Peats
If right: Your answer is correct.
If wrong: Your answer is incorrect.

Q: Soil organic matter content is determined by the balance between humification and oxidation of the plant residues that reach the soil. Greater plant productivity generally results in greater amounts of residues and hence greater soil organic matter.
- True
- False
A: True

Q: Soil organic matter influences plants directly when plants take up growth stimulating components, and when plants are affected by allelopathy. An allelopathy is defined as:
- refers to the chemical inhibition of one species by another. The "inhibitory" chemical is released into the environment where it affects the development and growth of neighboring plants.
- when two plants that share the same growing space exhibit the same characteristics as they mature and develop.
- refers to the need for plants to grow with other plants in a form of relationship meeting each others needs and aspirations. 
- no answers are correct
A: refers to the chemical inhibition of one species by another. The "inhibitory" chemical is released into the environment where it affects the development and growth of neighboring plants.
If right: Your answer is correct.
If wrong: Your answer is incorrect.

Q: The ratio of carbon to nitrogen in organic residues exerts a major influence over the rate of decomposition and the balance between immobilization and mineralization. In material with a C/N ratio greater than 25, nitrogen is likely to be immobilized from the soil solution causing a period of _______________ to occur.
- clinical mastitis
- nitrogen depression
- greenhouse effect
- leaching
A: nitrogen depression
If right: Your answer is correct.
If wrong: Your answer is incorrect.