Soil Science WEB Exam 12 ----- Fall 2007 - Dept. of Soil, Water and Climate- Soil pH
Directions 1. There is ONE BEST answer per question. 2.Place your answers on answer sheet, you only need to turn in the answers.
Name ___________________
1.________ 2._______ 3._________ 4._______ 5.______ 6._______ 7._________ 8._______
9.______ 10._______ 11. _________ 12.________ 13.______ 14.________ 15._________
Total= _______
______________Soil pH___________________________
1) By measuring the concentration of H+ ions in the soil solution you have determined the ___?___
a) concentration of H+ ions on the exchange complex
b) soils buffering capacity.
c) pH of the soil
d) H+ concentration in the total soil system
2) If a soil has a pH of 3.0 or less it most likely has __?___
a) the condition known as acid sulfate soil
b) saline soil conditions present
c) organic acids from the decomposition of soil humus
d) CaCO3 abundant in the soil
3. When using a pH meter with an electrode to determine the pH of a soil that has a high salt content, it would be best to mix the soil with -----?----- before taking the reading.
a) de-ionized or distilled water b) 1 M KCl mixture c) 1 M CaCl mixture d) rain water
4. If a soil has a pH of 5.5 it would have a base saturation of about___?___
a) 20% b) 40% c) 50% d) 60%
Table 1. Base and Acid Data for Soil A and Soil B
| Soil | CEC in meq/100 g |
Ions on the Ca |
Exchange Mg |
in H |
Meq K |
/100g Na |
| A | 40 | 20 | 10 | 6 | 2 | 2 |
| B | 22 | 6 | 2 | 10 | 3 | 1 |
5. Hydrogen Saturation for Soil A is_____?___
a) 15% b) 35% c) 65% d) 75%
6. Base Saturation for Soil B is ____?__
a) 30% b) 40% c) 50% d) 60%
7. The pH for Soil B would make it an _____ soil and the pH for Soil A would make it an _______ soil. (Hint: determine % B.S. and use BS vs. pH chart )
a) alkaline .........neutral
b) acid ...... acid
c) neutral ... ... alkaline
d)acid...... alkaline
8. Saline-Sodic soils will_________
a) have too much sodium on the exchange
b) effervesce with HCl
c) have improved water uptake over non-saline soils
d) have accumulations of NaCl and or KCl
9. When the lime requirement is determined for a soil, the information needed to make the decision about the amount to apply is the ___?___
a) parent materials, type of B horizons, and location in the state
b) kind of subsoils and amount of rainfall
c) original vegetation (forested soils in the east -prairie soils of the west).
d) CEC and Base Saturation.
10. What is the amount of lime needed to raise the pH of a soil to 80% Base Saturation. The soil currently has a 45% Base Saturation and a CEC of 30 me/100g.
a) 4 tons b) 5 tons c) 6 tons d) 7 tons
11. Not all soils are managed in a way to promote plant growth. The plant shown in #11 has leaf chlorosis, but this is not a nutrient deficiency. It most likely is caused by _____?___.
a) too acid a soil pH
b) soil CEC too high
c) salt damage due to high salt content of soil
d) too alkaline a soil pH
12) The picture for #12 shows a soil. The CEC for this soil would most likely be in the range of ____ to ____meq/100g of soil
a)2-4
b) 6-9
c) 10-14
d)17-19
13. In a soil testing laboratory the Cation Exchange Capacity (CEC) is determined by __?__
a) remove all cations and total the amount of all the cations removed
b) saturate the soil with NH4+, replace the NH4+ by Ca++, and measure the total quantity of NH4+ removed.
c) saturate the soil H+, measure the pH, add Ca++ to replace the H+ and measure the pH after all the sites are occupied by Ca++
d) determine the number of cation adsorption sites per unit weight of soil by weighing the soil first at saturation with cations (100 grams) and later after the soil has been leached, weigh the soil again.
14. Based on all that you studied in this
unit, what was the cause of the damage to this limestone statue in picture #
14?
a) carbon additions from CaCo3 as the limestone weathers.
b) acid rain reacting with the limestone of the statue to gradually dissolve the limestone.
c) salt damage from aerosol spray of salt that is put on roads during the winter, with the resulting damage taking place in the spring as temperatures rise.
d) Damage caused to historical sites in the 1991 bombing of Iraq by American forces.
15. A soil with 2.3 % OM and 12 % clay would have a CEC of approximately __?_ Meq/100 g
a) 4.6; b) 10.6; c) 14.6; d) 24.6
