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Soils can be deep, shallow, new, old, bright orange, black, or even blue (And anywhere in-between)! What soil looks like depends on the location that it forms in. It can take over 500 years to form an inch of topsoil on the surface! This lesson is split into three different PowerPoint presentations based on different topics. Soil Formation – Processes details how new soil can appear in a new location, and how soil looks change over time.
Like humans, soils have different properties based on where they are from, and where they “grew up” (formed). Soils have 6 major horizontal layers, or horizons that can be present. These horizons are often present in different types of soil, but each area usually has soils that have similar properties if they are near each other. Soil particles are moved by water, wind, ice, or formed in place from the rocks. Soils form differently for many reasons, and The CLORPT PowerPoint details major soil forming factors: CLimate, Organisms, Relief, Parent material, and Time.
The PowerPoints are appropriate for grades 4+. This presentation is split into three PowerPoints for downloading ease. There are some pretty complex processes that can be discussed at length in older students. Some of the activities listed are for all age groups.
3) Describe each horizon?
4) Describe how a soil will change with time.
A horizon forms
Horizons get thicker
May get redder if well drained or get grayer if wet
E horizon becomes more evident
5) Describe a local soil.
Glossary of terms:
In current glossary:
Other glossary words:
Additions – to add material or substance to the soil
Losses – to remove material or substance from the soil
Translocation – to move material or substance within the soil without adding or removing anything
A Horizon – topsoil, mineral soil horizon with enough OM to make it appear darker (blacker or browner than horizons below it)
B Horizon – subsoil, zone of accumulation of material from above due to leaching or eluviation
C Horizon – a horizon composed of material that the soil has formed from
R Horizon – solid rock, bedrock
O Horizon – a horizon rich in organic mater
Soil Monolith – a physical representation (model) of a soil profile
Activities or information:
1) General Soils:
Lesson Plans -Soil Society of America (All Grades) Good background with links to other areas
Educational Links - USDA NRCS (Grades K-6) This page lists several other links for additional information from USDA-NRCS. Includes some basic information and appropriate for lower grades
2)Soil profile photos and description:
State Soils Map (All Grades) This has information and photos of all the state soils. They do not label the horizons.
The Dirt on Soil - Discovery Channel (Grades 4+) Provides another discussion of the soil profile.
New England Soil Horizons (Grades 4+, perhaps more towards 8-12) A PowerPoint presentation can be followed from this site. Good overview for upper levels. Focuses on New England profiles but can be used in other areas
New England Soil Photos (All Grades) Photos of New England soils.
Soil Formation and Classification (Grades 8+) USDA-NRCS discussion of soil forming factors (CLORPT). Part of web page deals with soil taxonomy which is too advanced for K-8.
New England Soil Genesis (Grades 4+, perhaps more towards 8-12) A PowerPoint presentation can be followed from this site. It is a bit advance for 4th grade but could be used by the teacher for additional information and some examples. It focuses on the New England region but some of the information is general enough to be used in other areas.
Soil Mini Monoliths - USDA NRCS (Grades 4+) A description of how to make soil profile cards (mini-monoliths) is provided. This exercise works best with very dry, ground (pulverized) soil materials. It is difficult to get good results it the soil material is sandy (or sand sized) as the tape is not sticky enough to hold the sand.
1) How long does it take an inch of soil to form?
It may take hundreds to thousands of years. It will take longer in colder and drier regions than in warmer and wetter regions. This is due to the soil forming processes such as translocation and transformation being slower in cold and/or dry areas. Essentially, chemical reactions (weathering) occur faster as temperature increases. Since soil formation also requires organisms and organisms require water, reactions (formation) occur faster if there is sufficient water present.
2) Define the following:
3) Give example of the following:
rain adds water, dust adds minerals, as plants die and animals poop organic mater is added, humans also add fertilizer
evaporation, nutrient up take, leaching of nutrients and elements
gravity pull water and dissolved materials down, OM can move in many directions due to critters, clay movement, eluviated horizon
decomposition, weathering, iron rusting (reddening) or dissolving (graying), clay formation
4) Draw a young soil profile, medium age and older profile.
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