Second Hour Exam, March 6,  2002    
Average 94.1
Median 94
Std_Dev 4.01

March 6,, 2002

Hour Exam #2, SOIL 5813
Soil Plant Nutrient Cycling and Environmental Quality


1.     Mullen et al., indicated that the increase in carbon dioxide levels in the atmosphere (260 to 340 ppm in the last 150 years) have been in part due to the

                    a.  depletion of fossil fuels

                    b.  depletion of soil organic matter caused by land-fills

                    c.  depletion of soil organic matter via cultivation

                    d.  mysterious soil microflora recently discovered in Ghana

2.     Mullen reported that a worldwide decrease in soil organic matter of 3, 2, and 1% resulted in 20, 12,5, and 5 mg/kg increases in atmospheric CO2

What would be the CO2 increase (mg/kg) that could be attributed to decline in soil organic matter if average soil OM were to have decreased by 4%?

Regression equation:  increase CO2 = 7.5(om) -2.5


3.     Wright et al. (2001) indicated that the most effective system available for offsetting rising CO2 levels was

a.      continuous maize production

b.      continuous rice production

c.      continuous wheat production

d.     adoption of agroforestry systems

4.     Ranney (1969) reported the following equation for computing percent organic matter from percent organic carbon data.

a.      OM = 1.80 + 0.35(organic carbon)

b.      OM = 0.5 + 1.75(organic carbon)

c.      OM = 0.4 + 2.00(organic carbon)

d.     OM = 0.35 + 1.80(organic carbon)

5.     Moffat (1997) in a report on resurgent forests noted that

a.      Increase forested lands is the only viable method available to man that can sequester all the excess CO2 in the atmosphere

b.      previous estimates of the carbon sequestered by forests were low, since they did not take into account the large amount of carbon in peat.

c.      Increase in biomass and organic matter on U.S. forest lands over the last 40 years has stored enough carbon to offset 25% of the U.S. greenhouse gas emissions for that period

6.     Vigil and Kissel (1991) “Estimating amount of N mineralized from crop residues” reported that

a.      90% of the amount of N mineralized could be explained by a regression equation that included lignin and the hemicellulose-to-N ratio

b.      80% of the amount of N mineralized could be explained by a regression equation that included N and the lignin-to-N ratio

c.       40% of the amount of N mineralized could be explained by a regression equation that included N and the cellulose-to-N ratio

7.     The Kyoto Protocol does not currently permit

a.      sequestration in agricultural soils (crop production) to produce C sequestration credits

b.      sequestration via reforestation

c.      sequestration via the use of automobiles that consume CO2

8.    Lohry (1998) suggested that global warming could be compensated somewhat via high-yield agriculture.  Circle those statements that came from his paper and that are consistent with his beliefs.

a.      increased CO2 in the atmosphere can be combated only by decreasing fossil fuel emissions.

b.     projecting an average U.S. corn yield of 275 bu/ac in the future would mean assimilation by the crop of 1,778 million metric tons of CO2

c.      increased assimilation of CO2 by the U.S. corn crop (1960 vs. 1997) has come from increased use of fertilizers, higher yielding hybrids, better weed control

Student Questions:

1. Which of the following is (are) method(s) that will reduce gross atmospheric CO2?

a.      Agro-forestry and reforestation

b.      rainfall over the temperate forests

c.      green revolution

d.      using zero-till practices


2.  Humus

a)  serves as source of nitrogen, phosphorus, and sulfur to higher plants

b)  improves soil structure, drainage, and aeration

c)  decreases water holding, buffering, and exchange capacities

d)  retards the dissolution of silicate minerals

e)  serves as a source of energy for the growth and development of microorganisms


3.  Why are calcareous soils rarely high in organic matter?

a. Lignin is soluble in alkali solutions

b. Cellulose is soluble in alkali solutions

c. Lignin is insoluble in high alkali solutions

d. Because OU is the worst team in the Big 12 and will likely choke in the third round of the "Big Dance." ...If not before.


4.  Why is it difficult to measure and verify that carbon is actually increasing or decreasing in a relatively short period of time?

The method of testing has a margin of error to large to detect small changes.


5. Which of the following are correct?

a.  The largest carbon sink is found in earth’s oceans

b.  The organic matter of tropical soils generally contain high lignin    

compared with temperate soils regardless of the source of organic matter

c.  Expansion of agroforestry practices to marginal lands is suggested to be one way of sequestering carbon

d.  Industrialized countries are responsible for the 1.5 - 2 ppm CO2  increase per year

e.  Photosynthesis is one of the processes that remove CO2 from the atmosphere and we can conclude that the C4 plants like corn and sorghum are by far better in sequestering CO2 than C3 plants

6. Which solution could enable Lignin to decompose quickly?


a. hot water.

b. cool water.

c. acid solutions.

d. neutral organic solvents.

e. alkali solutions.

7.  Concerning the increase CO2 emissions in the atmosphere, if it is true that we have only been recording CO2 amounts and fluctuations for the past 150 years(at most), and that there have been several major fluctuations in CO2 levels before our current one that we have not had the technology to sense,  would this not lead us to the conclusion that all the concern about CO2 emissions and global warming may be a little out of order because we have recorded such a small amount of data over a relatively small amount of time?

a.  NO, because the rate at which we are now emitting CO2 is much greater than at any time before and we can trace that increased rate to global warming directly.

b.  YES, because there are several possible events (volcanic explosions for an example) that would have released huge amounts of CO2 into the atmosphere, causing atmospheric disturbances.


8.      List three methods for improving C sequestration in agricultural lands

conservation tillage

cover crops

legume interseeding


taking marginal lands out of production


BONUS:(5 points)


Outline the countries of Costa Rica, Ghana, Japan, Turkey, and Somalia