Cyber Field Trip Student Experiment
Test the Earth: Soil Comparison Between the Galapagos Islands and Your Home
Critical Thinking Questions
Soil may be defined as the naturally deposited material that covers the Earth's surface and is capable of supporting plant growth and development. All life on Earth, including plants, animals and human beings, depends on soil for existence. Soil is formed as a result of natural decomposition processes that occur over extremely long periods of time. There are five basic factors involved in the formation of soil:
Natural soils vary greatly in their composition. Because soil formation requires a long period of time and all life depends on soil in some way, conservation and management of soil is critical. Soil testing, or analysis of soil composition, is a very important step in the conservation of soil.
- material from which the soil is derived
- living organic matter
- slope and land form, or "relief"
Use the glossary to define any unfamiliar terms:
- Three clean milk containers, cut in half
- Soil test kit
- Air thermometer
- Soil thermometer
- Wear safety goggles when handling chemicals
- Take precautions against poisonous, stinging or biting animals/insects in the field
- Follow all laboratory and field safety regulations!
- Identify three different areas of your school grounds or garden from which you will collect soils. Make notes regarding the environmental conditions of the area from which you will collect sample, e.g., "collected on the damp side of the tool shed"; "by the roots of the shady oak"; "on the edge of the pond about 5 feet from the water, lots of gnats"; "sunny, dry spot in the middle of the field"; etc. Record this data in the Soil Analysis Data Chart observations section.
- Before taking the soil samples, measure and record the soil temperature and the air temperature right above the soil. Record this data in the Soil Analysis Data Chart temperature sections.
- Using the milk containers, collect about a half of a deciliter (approximately one pint) of soil from each of the three different areas.
- Following the directions of your soil test kit, analyze the soil samples for levels of nitrogen (N), potassium (K) , phosphorus (P) and acidity (pH).
- Record the values for all three samples of each test in the Soil Analysis Data Chart.
- Click the "Chart My Data" button to compare your data to the Galapagos Islands soils collected and measured by Sherri. (Data from samples will be added from Wednesday, December 9, through Friday, December 11, 1998.)
Any soil analysis kit that reports its values as "pounds per acre" should be converted to PPM (2 PPA=1 PPM)
CRITICAL THINKING QUESTIONS
- Based on your soil analysis and that of the Galapagos Islands, do you think a relationship exists between soil and temperature? If so, what is it?
- What differences in macronutrient levels exist between your environment and that of the Galapagos Islands? Between different islands of the Galapagos?
- Based on your findings, create a hypothesis about the differences between (a) local and Galapagos Island soils and (b) soils from island to island.
- Are there differences in the pH levels of the soil samples? What factors might lead to these differences?
- Is it useful to present your data or the Galapagos Islands data as averaged values, rather than as individual measurements? How do the data support your conclusions?
Scientific American Frontiers
Fall 1990 to Spring 2000
Sponsored by GTE Corporation,
now a part of Verizon Communications Inc.