Why We Study Soils:  Soil is one of our most precious natural resources  Soil integrates all other parts of the ecosystem  Soil provides a medium for plants so that we can have food, clothing, and other materials  We use soil to build on, walk on, and play on  Soil filters water, decomposes waste, stores heat, and exchanges gases  Soil is alive! It is the home of billions of large as well as microscopic organisms  Soil is a source of material for construction, medicine, art, and other uses 1-1

Why We Study Soils (continued):  Soils provide a snapshot of the geologic, climatic, biological, and human history at the place they are found  There is a limited amount of soil that can be used for growing food, and all the other uses we require  When improperly managed, soil can be eroded, polluted, or destroyed. It can also cause damage to other parts of the ecosystem.  Scientists need to know more about what the properties of the soil are all over the world so that we can study them, protect them, and use them properly 1-2

The Five Soil Forming Factors :  The properties of a soil are a function of: – Parent material – Climate – Topography – Biota (organisms, including humans) – Time  The result is a unique soil profile made up of layers called horizons  For the GLOBE Soil Characterization Protocol, we will be describing, sampling, and analyzing the soils from horizons of different soil profiles 1-3

How Do Scientists Use Soils Data?  Soil Thematic Maps of USA: The following 2 images are thematic maps made by interpreting the physical or chemical properties of soils, their horizons, and profiles. They were generated by using existing USDA and FAO soils data. Limitations for Agriculture, for example, would take such factors as soil pH, slope, texture, depth to bedrockand other factors into account in rating a soil. Soil Scientists need more data to make these kinds of products better. 1-4

Continental Soil Characterization: 1-5

U.S. Soil Fertility: 1-6

 Composite DMSP/OLS Image: The next image is a map of urbanization in the US created from a satellite that takes pictures of the Earth at night. The satellite sensor “sees” the lights from the cities. The “city lights” image is turned into an urban map using a computer. (Note how our cities have grown up along the interstate highway system). We can use maps like this to overlay on soils data (such as the UN/FAO Soils Map) to see how soils are being used for different forms of land use. How Do Scientists Use Soils Data? (continued): 1-7

Urbanization in the U.S.: 1-8

How Do Scientists Use Soils Data? (continued):  Scientists also use soils data for developing and testing models of soil processes. These soil models are linked with models of other parts of the ecosystem so that predictions can be made about effects of change on the earth. The following is an example of the structure of an ecosystem model that uses soils information as an important component. 1-9

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Soil Characterization:  For the GLOBE Soil Characterization Protocol, we will be describing, sampling, and analyzing the soils from horizons of different soil profiles  Soil Characterization requires at least two study sites. 1. near the Atmosphere study site 2. within the Biology study site  Field measurements for soil characterization are made only once at each sample site. Three replicate samples from each horizon are taken for lab or classroom analysis, and reported only one time for each site. 2-1

Locating a Soil Characterization Sample Site:  Safe for digging. Check with local utility companies and maintenance staff to ensure that you do not dig into or disturb a utility cable, water, sewer, or natural gas pipe, or sprinkler irrigation system  Under natural or representative cover. Find a relatively flat location with natural vegetation.  Relatively undisturbed. Keep at least 3 meters from buildings, roads, paths, playing fields or other sites where the soil may be compacted or disturbed by construction.  Oriented so that the sun will shine on the soil profile to ensure that the soil characteristics are clear for both naked-eye observations and photography. 2-2

Record on the Soil Characterization Data Work Sheet for each Horizon that is at least 3 cm thick:  The number of the horizon  The top and bottom boundaries of each horizon, in centimeters (where tees or nails have been placed)  The moisture status of the sample (wet, moist dry)  Soil structure  Soil color code as given in the Soil Color Chart (main and second color if present)  Soil consistence  Soil texture  The amount of roots and rocks  The presence of free carbonates (reaction with vinegar) 3-1

Characterization and Sampling Options: 1. Soil Pit Technique: Dig a soil pit at least 1 meter deep and as big around as is necessary to easily observe all of the soil horizons from the bottom to the top of the pit 2. Existing Exposed Soil Profile Technique: Use a road cut, excavation site, or other location where the top 1 meter of soil has been exposed. 3. Auger Technique : Use an auger to remove soil samples to a depth of 1 meter 4. Near Surface Technique: Use a garden trowel or shovel to sample only the top 10 cm of soil, if digging to a depth of 1 meter is not possible. 2-3

Auger technique: 1. Identify an area where you can dig four holes where the soil profiles should be similar. 2. Spread a plastic bag, tarp, board, or other surface on the ground next to your where you will dig your first hole. 3. Assemble a profile of the top 1 meter of the soil by removing successive samples with the auger and laying them end-to-end as follows: 2-7

Auger Technique (continued): 3.1. Turn the auger one complete revolution (360 o ) to dig into the ground Remove the auger with the sample in it from the hole Hold the auger over the plastic bag, tarp, or board Transfer the sample from the auger to the plastic bag, tarp, or board as gently as possible. Place the top of this sample just below the bottom of the previous sample Measure the depth of the hole. Adjust the sample on the plastic bag, tarp, or board so that its bottom is no further from the top of the soil profile than this depth.  Once the soil has been exposed on the ground follow the directions as given for the Soil Pit Technique. 2-8

Soil Texture:  The way the soil “feels” is called the soil texture.  Soil texture depends on the amount of each size of particle in the soil.  Sand, silt, and clay are names that describe the size of individual particles in the soil. –Sand are the largest particles and they fell “gritty” – Silt are medium sized, and they feel soft, silky or “floury” – Clay are the smallest sized particles, and they feel “sticky” 3-9

3-10 Size Comparisons of Soil Particles:  Sand ( mm, USDA) ( mm, ISSS)  Sil t ( mm, USDA) ( mm, ISSS)  Clay (< mm) Sand Silt Clay

To Determine Soil Texture: Step 1. Start with triangle #1  Test for CLAY First : If the soil is sticky, hard to squeeze, can form a long ribbon or worm without breaking, stains your hands, has a shine when rubbed, call it a CLAY (using triangle 1).  If it is like a clay but much softer and not as sticky,call it a CLAY LOAM (using triangle 1).  If it is very soft and is not like a clay at all, call it a LOAM (using triangle 1). 3-11

To Determine Soil Texture: Step 2. Next, use triangle 2  Next, try to feel for sand. If the soil has a “gritty”, sandy feel to it, add the word SAND (or SANDY) to the classification from triangle 1 (shown on triangle 2)  If you can’t feel any sand, and the soil has a smooth feel (like flour), add the word SILT or SILTY to the classification from triangle 1 (shown on triangle 2)  If you can feel “some” sand, but not a lot, keep the same classification you had from triangle 1, and don’t change it.  Record the texture class name of your soil sample. 3-12

Soil Structure:  Soil structure is the shape that the soil takes based on its physical and chemical properties. Each individual unit of soil structure is called a ped. Possible choices of soil structure are: with structurestructureless Granular Blocky Single Grained Platy Massive Prismatic Columnar 3-2

Soil Structure (continued): OR: Single Grained (like beach sand) or Massive (solid mass with no shape) 3-3

Soil Color: 1. Take a ped from each horizon and note on the data sheet whether it is moist, dry, or wet. If it is dry, moisten it slightly with water from your water bottle. 2. Stand with the sun over your shoulder so that sunlight shines on the color chart and the soil sample you are examining. 3. Break the ped and compare the color of the inside surface with the Munsell color chart. NOTE: Sometimes, a soil sample may have more than one color. Record a maximum of two colors if necessary, and indicate (1) the Main (dominant color), and (2) the Other (sub-dominant color). 3-4

Soil Color (continued): Munsell Notation The Munsell code below each color in the GLOBE color chart is a universal notation which describes the soils’ color. The first set of number and letter symbols represents the Hue,  Hue represents the position of the color on the color wheel (Y=yellow, R = red, G=green, B=Blue, YR=YellowRed, RY=Red Yellow). 3-5

Soil Color (continued): The number before the slash is the Value  Value indicates the lightness of a color. The scale of value ranges from 0 for pure black to 10 for pure white. The number after the slash is called the Chroma  Chroma describes how “intense” the color is. Colors of low chroma values are sometimes called weak, while those of high chroma are said to be highly saturated, strong or vivid. The scale starts at zero, for neutral colors, but there is no arbitrary end to the scale. 3-6

Soil Color (continued): HUE VALUE CHROMA 3-7

Soil Consistence  Take a ped from the top soil horizon. If the soil is very dry, moisten the face of the profile with a water bottle with a squirt top and then remove a ped for determining consistence.  Holding it between your thumb and forefinger, gently squeeze it until it pops or falls apart. Record one of the following categories of soil ped consistence on the data sheet. – Loose: You have trouble picking out a single ped and the structure falls apart before you handle it. – Friable: The ped breaks with a small amount of pressure. – Firm: The ped breaks when you apply a good amount of pressure and dents your fingers before it breaks. – Extremely Firm: The ped can't be crushed with your fingers (you need a hammer!). 3-8

Presence of Roots:  Observe and record if there are none, few, or many roots in the horizon Presence of Rocks:  Observe and record if there are none, few, or many rocks in the horizon. A rock is defined as being larger than 2 mm in size. 3-13

To Test for Free Carbonates:  Free carbonates are salts that coat soil particles. They form under certain conditions such as in dry climates where the pH is above 7. They are also found in soil profiles that have parent materials made of carbonates (such as limestone).  This test is performed by squirting vinegar on the soil. If free carbonates are present, they will “effervesce” or bubble when the vinegar reacts with them. Record one of the following based on your observation: – None : you observe no reaction (the soil has no free carbonates) – Slight: you observe a slight amount of bubbling (the soil is coated with some carbonates – Strong: you observe a strong reaction (many bubbles) (the soil has many carbonates present) 3-14