Soil Science Test 3 Updated Actual Questions And Correct Answers

SOIL SCIENCE TEST 3 UPDATED ACTUAL
QUESTIONS AND CORRECT ANSWERS
Question:
1. What size are soil colloids?
Answer:
.1-.001 micrometers

Question:
2. what is an inorganic colloid
Answer:
makes up the bullk of soil colloids clay minerals usually crystalline

Question:
3. organic colloids
Answer:
highly decomposed OM have a greater influence on soil properties (per weight) than inorganic

Question:
4. what is the ratio of elements in the tetrahedral layer?
Answer:
1 silicon:4 oxygen

Question:
5. what is the difference between 1:1 and 1:2 silicate clays?
Answer:
1:2 absorbs more water

Question:
6. what two things make up soil organic matter?
Answer:
decomposed residue and organisms

Question:
7. What are benefits of soil organic matter?
Answer:
can fix almost everything stability rainfall infiltration and aeration water holding capacity nutrient
cycling buffering capacity insect/microbial activity ion exchange and infiltration

Question:
8. what is humus
Answer:
highly stabilized OM high CEC prevents rapid change in pH

Question:
9. clay vs humus CEC

, Answer:
humus has a greater cation exchange capacity than clay

Question:
10. anion exchange capacity
Answer:
sum of total anions that a given soil can absorb

Question:
11. cation exchange theory
Answer:
sum of total cations that a given soil can absorb

Question:
12. where does charge come from?
Answer:
within the octahedral or tetrahedral lattice at the surface of the colloid

Question:
13. What is isomorphic substitution
Answer:
creates a permanent charge by substituting Mg or Fe for Al in a lattice

Question:
14. Why do we lime soil?
Answer:
gets rid of hydrogens to make room for nutrients consumes H+ which decreases acidity

Question:
15. anion+cation=
Answer:
molecule

Question:
16. explain cation exchange
Answer:
the exchange bt a cation in the solution and another cation on the surface of a negatively charged
colloid

Question:
17. Absorption strength order of elements
Answer:
Al3+ > Ca2+ > Mg2+ > K+ = NH4+ >Na+ > H+

Question:
18. what factors influence cation exchange
Answer:
strength of absorption and relative concentration of cations in the soil solution