1. Soil Structure

What is the difference between soil texture and soil structure?

Which would be more likely to change as a result of soil compaction, bulk density or particle density? Why?  

An unit of non-structure in which there is no bonding between adjacent particles is called:

(a)     blocky

(b)     single grained

(c)     platy

(d)     granular

(e)     massive

Connect the type of structure with the word that most accurately describes its shape:

Granular	Cubical
Blocky	Tall
Prismatic	Spherical
Platy	Wide

In the space between peds

(a)     water is stored  
(b)     air is exchanged between the soil and the atmosphere  
(c)     root growth occurs  
(d)     nutrients are stored  
(e)     both a and d  
(f)       both b and c

How are aggregates formed?

Name two different cementing agents.

Why is soil structure important?

What problems would you expect to encounter for a housing development if you observe mottled soil color near the soil surface?

2. Chelates

What is a chelate?

Name three types of organic molecules that chelate with metals.

Describe the importance of chelates

What is a siderophore?

3. Adsorption of Ions

Why are soils with high CEC more fertile than soils with low CEC?

A purple cationic dye is filtered through 3 different soils. The filtrate for each appears as follows:

Soil A	light purple
Soil B	almost clear
Soil C	light pink

Which soil:
Has the greatest net negative charge?
Most likely is a clay or clay loam?
Is likely to have the greatest percentage of sand?

Which of the following chemical equations represents the cation exchange process in soils?

(a)  NH₄⁺ + H-soil ----> NH₄-soil + H⁺
(b)  6CO₂ + 12 H₂O ----> C₆H₁₂O₆ + 6O₂ + 6H₂O
(c)  organic matter + O₂ ----> CO₂ + H₂O + humus
(d)  KNO₃ ----> K⁺ + NO₃^-
(e)  H-soil <----> H⁺ + soil^-

What is the significance of CEC?

How does DDL affect whether colloidal particles are dispersed or flocculated?

4. Soil Acidity

Liming is necessary to neutralize:

(a)     active acidity

(b)     reserve acidity

(c)     total acidity

What processes can lead to acidification of the soil?

 

5. Interaction between soil water and soil air

Which would exhibit a higher water content at saturation - a sand, silt loam, or clay loam?

Which could store the most water in plant available form - a sand, silt loam, or clay loam?

As soil pore space increases, particle density

(a)     increases

(b)     decreases

(c)     remains unchanged

What practices can increase both thermal admittance and diffusivity?

What is one reason that mineral matter is a better conductor than organic matter?

6. Interaction between organic matter and soil air

What accounts for variation in soil organic matter decomposition both within a site and between sites?

What function does organic matter decomposition serve in the soil?