Web Exam 10
Soil Science WEB Exam 10-- Fall 2008- Dept. of Soil, Water and Climate
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= _______
_________________________________________
15 Questions
1. Select the factors that are important in maintaining adequate levels of Soil Organic Matter (SOM).
a) proper maintenance of soil fertility
b) crop rotations that aid in adding SOM below the soil surface
c) tillage practices that reduce air incorporation and reduce soil temperatures
d) all of the above.
2. The main reason that virgin prairie soils have more soil organic matter (SOM) then the same soil that has been cultivated and used for crop production for 30 years is because ______________ .
a) of the increase in temperature and aeration as a result of cultivation. b) the large amount of roots and leaves added each year in a prairie soil is less then what is added in a cultivated soil.
c) the cultivated soil has less of the highly decomposable organic matter additions. d) the variety of fresh organic debris is very different for each system and thus the SOM is different.
3. Different cropping systems (corn vs. soybeans vs. wheat) result in the soil organic matter levels changing because different cropping systems _____.
a) leave different amounts of organic residue each year for incorporation.
b) create different temperature and moisture conditions
c) have variable levels of Nitrogen and Phosphorus in the residue
d) have variable root systems that are able to bring up SOM from deep in the profile.
4. If a soil with 3.5 % organic matter has added to it each year______?___ lbs. of plant residue the amount of humus will stay about the same. (See Equilibrium Concept of SOM)
a) 3200 b) 4200 c) 5200 d) 6200
5. A green manure is ______________.
a) a "green manure " if the green algae has been added to it.
b) the incorporation of any plant residue that at one time may have been green.
c) where the amount of nitrogen added with the manure will promote "green" plants.
d) the incorporation of a grass or grass like cover crop that was planted in the fall and is plowed into the soil in the spring ofen when it is still living.
6. Assume you make a compost pile of the following: a) 5 parts hay, 3 parts grass clippings and 2 parts legumes. What is the C:N ratio of the compost? Look at the C:N ratio for each material in the table of Unit 10/Chapt. 1.
a) 29:1
b) 39:1
c) 49:1
c) 59:1
7. Suppose you conducted a study of soils
developed under prairie vegetation to determine the tons per acre of soil
organic matter in the upper 40 inches of soil. Which states would have the
largest amount of SOM and which would have the smallest? Rank the states from
Largest to smallest amount of SOM in upper 40 inches. The states are:
a)
b)
c)
d)
8. The soil organic matter levels in the
upper 40 inches of the native soils of
a) decrease across the state as you go from west to east at the 45 ° of latitude.
b) increase across the state as you go from west to east at the 45 ° of latitude.
c) increase as you go from south to north in the middle of the state.
d) decrease as you go from the northeast corner to the southeast corner.
9. You collect an "intact" peat sample that is exactly the same as it is in the field, if you dry the peat and later completely burn the peat in a container. You have carefully weighed the peat before and after burning. The material that is left in the bottom of the container after burning is called _________.
a) fibers of peat b) mineral material c) organic materials d) air
10. The diagram is of a 15 foot deep Lake in 
a) mineral soil that is most likely poorly drained.
b) evidence of paludification of the area.
c) a hemic peat, formed by the lakefill process of peat formation.
d) part of a glacial moraine with a thick O horizon.
11. A 1.5 meter profile was excavated at point A. The horizons designations would most likely be __, __, __, __, __
a) A1, A2, A3, C1, C2
b) Oa1, Oa2, Oa3, C1, C2
c) Oe1, Oe2, Oe3, Oi1, Oi2
d) Oi, Oe, Oa, C1, C2
12. When a peatland is farmed for vegetables two serious problems are encountered. They are _____ and ______
a) deficiencies of micronutrients and wind erosion when the soil is dry.
b) subsidence of the peat and nitrogen deficiencies.
c) deficiencies of water in the profile and cold soil temperatures.
d) too low of a pH and difficulty of soil tillage.
13. The truck pictured can carry about
36 tons of soil. How many loads per year would it take to
equal the soil going past Winona Minnesota in the 
a) 2389 trucks b) 6389 trucks
c) 8389 trucks d) 9389 trucks
14. This factor in the USLE will vary in Minnesota going from small to large as you go from west to east.
a) rainfall factor
b) crop management factor
c) erosion control practices
d) soil erodibility factor
15. Use the USLE to determine the amount of
soil eroded from a field in
a) 11 tons b) 17 tons c) 22 tons d) 38 tons
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