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Carbon Sequestration and Agriculture

Student Directions

First, have someone in your group read the title of the paper, the general description, and the figure legend (below the figure). Then work together to address the questions.

The graph on the next page is from a study on the effects of two different agricultural methods on soil organic matter content in two corn fields. The researcher wanted to compare the soils under "no-till" (soil is not disturbed by plowing) and "plowing" (soil is plowed before planting) practices. This type of change in agricultural practice is of great interest to ecologists because "no-till" agriculture may help reduce CO2 concentrations in the atmosphere and therefore lessen global warming.

The graph is set up somewhat differently from what you are used to. They Y axis shows the depth of the soil in cm, going down from the soil surface. Therefore 0 cm is the soil surface, -10 cm is 10 cm below the surface, and so on. The X axis is concentration of carbon (C) in organic form in the soil. Units are Mg (a measure of mass; megagrams or 1,000,000 grams) of C per ha (hectacre or 2.2. acres)

1. Interpret the Graph:

First, look at and then interpret the figure in the following two steps:

Step One: Make sure you understand all parts of the figure - such as, the X and Y axes, the legends, all the words - plus the specific question being addressed and the experimental design. Then describe the findings - the data. Write your description below plus any questions you have (e.g. things you don't understand)

 

 

 

 

 

 

 

 

 

Step Two: Interpret the figure. Using what you know about carbon dioxide and plants, why did the scientist see this difference between the two agricultural practices? In regard to global warming and rising carbon dioxide concentrations is the atmosphere, what is the implication of this finding? (So what?) Write your interpretation, the implication, and any questions you may have. ). [HINT: Tillage of soils with farming machines breaks up the soil and allows more air to mix in, which enhances microbial activity.]

The data are from R. Lal. 1997. Residue management, conservation, tillage and soil restoration for mitigating greenhouse effect by carbon dioxide enrichment. Soil and Tillage Research 43: 81-107

2. Draw a concept map: Based on your understanding of the graph draw a concept map showing possible effects of "no-till" agriculture on CO2 concentrations in the atmosphere.

AttachmentSize
3. UCC_Carbon Sequestration Agri.doc733 KB
Lal.pdf1.76 MB
CGCEO_25.pdf363.34 KB