Soils Final part 1

Other things being equal, a soil with 30% clay of the _____ type would be expected to have the greatest potassium- fixing capacity. A: 2:1 B: 1:1

A (2:1)

To be classified as a conservation tillage practice, a system must leave at least ______% of the soil surface covered with plant residues? A: 30% B: 50%

A (30%)

In acid soils, the principal chemical form of phosphorous available for plant uptake is__________. A: H2PO4 B: HPO4 C: P2O5

A (H2PO4)

In which of the following epipedons is the organic matter level generally highest? A: Histic B: Mollic

A (Histic)

Given that you start with 40 g of soil, a 40 sec hydrometer reading is 20g and a 2 hr reading is 14g. What is the texture of this soil? (textural triangle is attached) A: Sandy Clay B: Loam C: Silty Clay Loam

.

Humus is an important soil colloid which of the following is NOT true? A: Humus is not capable of absorbing cation B: Humus has influence on soil aggregates stability C: Humus is very important in isomorphous substitution

A (Humus is not capable of absorbing cation)

The reaction: mica + H20 ----> K+ OH- + acid clay is an example of _________. A: Hydrolysis B: Hydration

A (Hydrolysis)

A cover crop is usually grown for the purpose_________? A: Improving Soil Physical properties and saving/recycling nutrients

A (Improving Soil Physical properties and saving/recycling nutrients)

Compared to an underlying silty clay B horizon, how much micropore space would there be as a percentage of total pore space in an overlying silt-loam A horizon A: Less B: Greater

A (Less)

Soil A has a redox potential of 400 mV, soil B-200 mV. Of the two soils, Soil B is more apt to be characterized by an abundance of ________. A: Mn^2+ ions B: Fe^3+ ions C: molecular oxygen

A (Mn^2+ ions)

To be practical, a nitrification inhibitor should kill or inhibit____________ A: Nitrobacter B: Nitrosomonas

A (Nitrobacter)

Using the feel method, a soil creates a medium ribbon when pinched between the thumb and forefinger, the ribbon feels rough (like sandpaper). What is the most likely soil texture. A: Sandy Clay loam B: Clay

A (Sandy Clay loam)

If a manager can afford only a limited amount of soluble P fertilizer for a calcareous soil with low phosphorus availability, the best plant growth is likely to be obtained if the P fertilizer is applied? A: in narrow braids or localized concentrations B: well in advance of the plant's main period of nutrient uptake

A (in narrow braids or localized concentrations)

Applied to agricultural crops, the term lodging refers to? A: plants falling over, often as a result of too much N B: short, stubby plants starving for N or S

A (plants falling over, often as a result of too much N)

Ammonium fixation would be expected to be greatest in soils containing a lot of __________. A: vermiculite B: Frankia C: Rhizobium bacteria

A (vermiculite)

In the early stages of plant nitrogen deficiency, the most obvious symptoms are_____________ A: yellowish colors in the oldest leaves B: yellowing colors in the youngest leaves

A (yellowish colors in the oldest leaves)

The partial pressure of oxygen in the atmosphere is .21 bar and that of nitrogen is .78 which of the following partial pressure levels would you expect to find in the pores of a moderately well drained soil? A: 0.30 (oxygen) B: 0.15 (oxygen)

B (0.15 (oxygen))

Given a H+ ion concentration of 0.0000000063, what is the pH of the soil? A: 4.7 B: 7.2 C: 6.5

B (7.2)

Organic matter additions to a soil can decrease? A: Dp B: Db

B (Db)

An excess of N typically____________ the maturity of annual plants? A: Delays B: Hastens

B (Hastens)

In order for nitrate to form from soil organic matter, __________ must be present A: Nitrosomonas B: Nitrobacter C: Both of them

C (Both Nitrosomonas & Nitrobacter)

In explaining erosion processes to a friend, which of the following would you say about accelerated erosion? A:It involves a much less rapid process than geological erosion B: It is greatly enhanced by the splash effect of raindrops impacting bare soil

B (It is greatly enhanced by the splash effect of raindrops impacting bare soil)

Alluvial Fans are usually characterized by________? A: Nearly level B: Sandy Gravelly

B (Sandy Gravelly)

The P factor in universal soil-loss equation is concerned with all but one of the following? A: Terraces B: Soil erodibility C: Contour tillage

B (Soil erodibility)

The following are characteristics of a water molecule. A: The two H atoms are on diametrically opposite ends of the molecule B: The H to O to H is approximately 90 degree Celsius C: It has a positive and a negative side

B (The H to O to H is approximately 90 degree Celsius)

Which of the following best characteristics the field capacity of a soil? A: Soil with water potential of -1500kPa B: Water content of a soil with water potential of about -10 kPa

B (Water content of a soil with water potential of about -10 kPa)

The process of aerobic respiration is a significant source of which of the following gases? A: oxygen B: carbon dioxide

B (carbon dioxide)

Aggregate dispersion can lead to soil: A: formation B: crusting

B (crusting)

Decreasing the organic matter content of a soil is likely to_________ A: have no effect on water holding capacity B: decrease the soil's water holding capacity c: increase the soil's water holding capacity

B (decrease the soil's water holding capacity)

Which of the categories in the Soil Taxonomy system indicates properties that have implications for root growth as well as for the construction of building foundations? A: subgroup B: family

B (family)

To monitor the effects of management on soil fertility, it is best to sample the soils in an area_______ A: Every one to three years B: from the same depth every time C: at the same season every time D: All of the Above

B (from the same depth every time)

The opposite process from mineralization is ____________ A: denitrification B: immobilization

B (immobilization)

In most soil, mineralization of soil organic matter is an important source of plant available __________. A: potassium B: phosphorus C: both a and b

B (phosphorus)

Some soil colloids exhibit positive charges under highly acid conditions. To what are these charges likely due? A: increase in the level of H+ ions on the exchanging complex B: protonation of some hydroxy groups by excess H+ ions

B (protonation of some hydroxy groups by excess H+ ions)

Fungal Hyphae have an important influence on soil structure because they_______________ A: Create large channels that enhance water flow and aeration B: stabilize macro aggregates

B (stabilize macro aggregates)

This form of sulfur must be oxidize before it can be taken up by plants is ____________. A: elemental sulfur B: sulfide C: sulfate

B (sulfide)

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_________. A: The Slope of the drain lines B: the texture and structure of the soil

B (the texture and structure of the soil)

In many soil profiles, the subsoil is high in clay, but is also quiet permeable to percolating water. Why? A: The subsoil may have an organic texture B: Clay generally promotes free water movement C: Prismatic structure may be well developed leaving micropores around the structures.

C (Prismatic structure may be well developed leaving micropores around the structures.)

The R factor of the Universal soil-loss equation is concerned with _________ A: terraces B: climate C: residue cover on the soil

C (residue cover on the soil)

Nitrogen is a component of which essential plant compounds? A: proteins B: chlorophyll C: enzymes D: DNA E: All of the Above

E (All of the Above)

The sulfur dioxide in the atmosphere___________ A: Can be important source of sulfur nutrition for plants B: Is a major contributor to acid rain C: Comes from fire such as fossil fuel burning volcanoes and forest fires D: All of the Above E: None of the Above

E (None of the Above)