Soils Exam 2

Compared to the bulk soil in which the earthworms live, earthworm casts contain ____.

more of most plant-available nutrients

In nature, beneficial mycorrhizae form with the roots of _____

all of the above

The fungal symbiont generally benefits from the mycorrhizal relationship by obtaining ____ from the higher plant

none of the above

In most soils the overall population (numbers) of microorganisms changes with time, generally following changes in the _____

supply of decomposable organic matter

The addition of large quantities of plant residues to the soil generally ____ the incidence and severity of soil-borne plant diseases.

Disease suppressive soil often results from _____.

Adding organic materials to the soil that stimulate diverse microorganisms.

What is functional redundancy, and how does it help soil ecosystems continue to function in the face of environmental shocks such as fire, clear-cutting, or tillage?

Why is species diversity important?

A mycorrhiza is said to be a symbiotic association. What are the two parties in this symbiosis, and what are the benefits derived by each party?

in what way is soil improved as a result of earthworm activity? Are there possible detrimental effects as well?

What is the rhizosphere, and in what ways does the soil in the rhizosphere differ from the rest of the soil?

What is a disease-suppressive soil? Explain the difference between general and specific forms of suppression

Species diversity

Fundamental redundancy

Rhizosphere

Root exudates

Bacteria

Actinobacteria

Fungi

Protozoa

Nematodes

Enchytraeids

Arthropods

Earthworms

Rhizobia

Mycorrhizal Fungi

Disease-suppressive soils

General suppression

Specific suppression

Modern nutrient management is designed to _____________.

all of the above

Buffer strips principally function in nutrient management to _______.

prevent the transport of nutrients from fields to streams

The place where the manure pile was stored last year, a narrow strip that used to be a limestone gravel farm road, and the spot where fertilizer is usually transferred from a nurse truck to the tractor spreader are all examples of parts of a 25 hectare field that should be treated as follows when sampling soil for the soil test lab

carefully avoided while sampling

For a year or so after clear-cut (even-aged) harvesting large areas of mature forest, the streams draining the watershed can be expected to carry ______ than before the harvest.

a much greater total nitrate load

Which of the following does not describe aluminum hydroxyl ions (such as Al(OH)2+) in the soil?

They are commonly applied to help reduce the soil pH for acid-loving plants.

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 sulfur-bearing minerals that produces sulfuric acid

Under which of the following conditions would you favor a finely ground dolomitic limestone as your choice of a liming material?

In humid regions repeat applications of limestone are needed after a few years primarily because of ____.

he groundwater under a heavily managed field is high in nitrates, but by the time it reaches a stream bordering the field, the nitrate concentration has declined to acceptable levels. What are likely explanations for the reduction in nitrate?

You want to plant a cover crop in fall to minimize nitrate leaching after the harvest of your corn crop. What characteristics would you look for in choosing a cover crop to ameliorate this situation?

Compare the relative advantages and disadvantages of organic and inorganic nutrient sources.

Discuss the concept of the limiting factor and indicate its importance in enhancing or constraining plant growth

Discuss the concept of Luxury Consumption (potassium).

Discuss the Law of Diminishing Returns.

Soil pH gives a measure of the concentration of H+ ions in the soil solution. What, if anything, does it tell you about the concentration of OH- ions? Explain.

Describe the role of aluminum and its associated ions in soil acidity.

What is meant by buffering? Why is it so important in soils?

What is acid rain, and why does it seem to have a greater impact on forests than on commercial agriculture?

Discuss the significance of soil pH in determining specific nutrient availabilities and toxicities, as well as species composition of natural vegetation in an area

A neighbor complained when his azalea (optimal pH 4-5) were adversely affected by a generous application of limestone to the lawn immediately surrounding the azaleas. To what do you ascribe this difficulty? How would you remedy it?

Nutrient management plan

Best management practices

Buffer strip

Cover crop

Conservation tillage

Sewage sludge

Sewage effluent

Biosolids

Soil pH

Buffering Capacity

Acid precipitation

Liming

Adsorb

Absorb

Cation

Anion

Cation exchange

Cation exchange capacity (CEC)

A soil pedon is ____.

Which of the following categories of Soil Taxonomy provides the greatest specificity of soil properties?

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

Brown and red colors in subsurface horizons are caused by __ in the soil.

Rearrange the following soil orders from the least to the most highly weathered: Oxisols, Alfisols, Mollisols, Entisols, and Inceptisols

Entisols, Inceptisols, Mollisols, Alfisols, Oxisols

What is the principal soil property by which Ultisols differ from Alfisols? Inceptisols from Entisols?

Of the five soil-forming factors discussed in Chapter 2 (parent material, climate, organisms, topography, and time), choose two that have had the dominant influence on developing soil properties characterizing each of the following soil orders: Vertisols, Mollisols, Spodosols, and Oxisols.

Explain why Soil Taxonomy is said to be a hierarchical classification system.

Soil individual

Pedon

Polypedon

Epipedon

Entisols

Relatively undeveloped

Inceptisols

Weakly developed, no clay accumulation

Andisols

Formed in volcanic materials and/or has specific mineral
properties related to density, phosphorus, and water holding

Gelisols

Has permafrost

Histosols

Dominated by organic (O) horizons

Aridisols

Arid region, salt, carbonates, or gypsum accumulations

Vertisols

Dominated by shrink-swell clay

Mollisols

Dominated by thick, dark-colored mineral surface, non-acid

Alfisols

Moderately weathered, clays accumulation, slightly acidic

Ultisols

Highly weathered, acidic, clay accumulation

Spodosols

Sandy an has an accumulation of organic matter, aluminum,
and/or iron

Oxidols

Most developed, dominated by iron and aluminum oxides