Soil Science WEB Exam 9 Fall 2007 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 _____
Soil Organisms, & Carbon Cycle & Nitrogen Cycle-----------------------------------------------------------------------------------------------------------------------------
1. The cycling of _______ and _______ takes place through the biosphere via
biogeochemical cycles when organisms consume the primary producers.
a) energy .....chemical elements b) organic matter......nitrogen c)
water.....energy d) temperature.....water
2. The carbon needed by autotrophs is supplied by the carbon in the
_____
a) deep oceans; b) atmosphere
c) soil; d) secondary consumers
3. The critter at the arrow for question 3 is found in Northern Minnesota
and is __?__.
a) beneficial due to increasing the carbon flow from leaf litter to the
soil
b) increasing the plant species on the forest floor
c) destroying the Oi and Oe horizons on the forest floor.
d) responsible for increasing the flow of carbon to the soil and atmosphere.
4. This area of the soil that the arrow (-->) is pointing at is called
the __?__. in the picture for question 4.
a) pedosphere
b) eluvialsphere
c) rhizosphere
d) troposphere
5. Fungi and Bacteria are the most numerous organisms in prairie and forest
soils and their ratio is______ fungi for ______bacteria in a prairie
ecosystem.
a) 10....50 b)50....10 c)100.....10 d) 1000 ....10
6. If the goal is to sequester carbon in the soil to reduce global warming,
the main thing to do is to _________.
a) increase soil organism populations in the soil b) improve the air exchange
between the soil and the atmosphere by tillage c) protect soils from the
warming of the sun by providing shade or more water. d) reduce tillage,
increase residues, and reduce oxygen exchange with atmosphere.
7.The soil organism ___?__ is capable of fixing atmospheric nitrogen without
needing any other organism.
a) Nitrobacter b) Rhizobium c) Mycorrhizae d) Azotobacter
8. Nitrogen is needed by most agronomic or horticultural crops in quantities
that are larger than normally found in soils. The main reason for this is
because..__?__.
a) the content of atmospheric nitrogen is low.... b) ) the nitrogen in the soil
is mostly in the organic pool and is not available to the plant.
c) the greatest amount of nitrate nitrogen is in a form the plant can absorb.
d) the conversion of ammonium to nitrate is too slow for the plant.
Use this Nitrogen Cycle to answer the questions 9-14.
9. The amount of nitrogen in the soil will vary
during the growing season, however at any one time the greatest quantity of
plant available nitrogen will occur in area __
a) A-- b) B-- c) D --d ) F
10. The kinds of nitrogen most likely in Pool D are ______.
a) R-NH2 and NH4+; b) NO3- & NO2-; c) N2 & N3; d) NH & NO
11. Nitrate reduction will take place when nitrogen goes from pool ___?__ to
pool__?__
a) C to B b) D to C c) E to D d) B to A
12. Adding Manure to a cold soil in the spring will not have nitrogen moving
from area ____ to area _____.
a) F to E; b) C to B; c) E to D; d) D to C
13. Recent studies in Minnesota show that the use of a nitrogen inhibitor
when added to sandy soils will reduce N in groundwater due to blocking the
nitrogen moving from pool __?__ to pool __?__.
a) D to C b) B to A) F to D) E to D
14. The bacteria Rhizobia spp. is responsible for getting N from pool __?__
to pool _?__to pool .
a) E to F b) F to D c) D to C d) B to A
15. Use the graph for #15. If you want to keep the nitrogen pollution of
water leaving the soil via drainage tile below the maximum contaminant level
(MCL) __?__
a) the amount of N fertilizer applied should be between L (low level of N
fertilizer) and M(Medium).
b) the amount of N fertilizer applied should be between M and H (High level of
N fertilizer).
c) the source of nitrogen should be other than a form of nitrate
fertilizer.
d) corn production cannot be sustained within this field under the current
rotation and management schemes without producing tile drainage water that
exceeds the MCL for nitrate.
