Soil Analysis Lab
Pre-lab Questions:
1. Define the following:
a. Porosity – the ability of a substance to absorb liquids.
b. Permeability – the quality of a substance that allows fluids or gases to pass through it.
c. Water holding capacity – amount of water that is available to plants in the soil.
d. Solution – a homogenous mixture of two substances.
e. Suspension – when small particles of a substance are dispersed throughout a gas or liquid.
2. What industries would find it important to know the structure of the soil?
The industries of agriculture, mining, construction, logging, and archeology would all find it important to know the structure of soil.
3. Using what you know about North Carolina now, would large scale use of septic tanks work well?
No, I don’t think the large scale use of septic tanks would work well at all. Generally, from my experience, the soil of North Carolina is primarily clay and not very permeable. If these large scale septic tanks were put into effect, I think it would not be broken down correctly and begin to ooze out of the ground.
Hypothesis:
If different tests are done to the different samples of soil, then the collected soil will be a sandy clay composition, a pH of 7 and not very permeable.
· Independent Variable: The soil used in the various tests.
· Dependent Variable: The composition, pH, and the permeability of the different types of soil.
· Controlled Variable: pH strip used, set up for permeability test
· Control: Topsoil & Sand
· Experimental: The soil collected
Problem: What is the composition, pH, and permeability of the collected soil, sand, and topsoil.
Materials
· Spray Bottles
· 3 Plastic Cups
· Rulers
· Wax Marker
· Soil Analysis Card
· Bag of Sand
· Bag of Clay
· Soil Sample
· Tap Water
· 4 Plastic Cylinders
· 4 Plastic Vials
· 4 Plastic Cups
· Cheesecloth
· Rubber Bands
· 60cc plastic medicine cups
· humus
· scissors
· balance
· Clock with Second Hand
· Twist Ties
Procedure
1. The first test is to determine the composition of the soil. First place a handful of the soil that needs to be tested in someone’s hand.
2. Moisten the soil. Follow the flow chart by answering the yes and no questions to determine the composition of the soil.
3. The pH test is performed by initially placing the soil being tested into a Petri dish.
4. Add water to the soil to create a mixture of water and soil.
5. Place the pH strip into the soil mixture and use the chart provided on the pH package to determine the pH of the soil.
6. The permeability test is done by initially setting up the cup on the stand so it is 1 inch above the beaker collecting the water.
7. Place 50 mL into a graduated cylinder.
8. Place the soil into the cup suspended into the stand and place a beaker below the cup to catch the water.
9. Pour the 50 mL of water that was in the graduated cylinder into the cup with the soil and begin timing as soon as water reaches the soil.
10. Continue to time until water comes through the soil and into the beaker. Measure the amount of water that was released into the beaker.
Observations:
· The collected local soil turned out to be sandy clay loam, the topsoil was concluded to be loamy sand, and the sand was sand.
· The topsoil had by far the fastest flow time taking only 2.33 seconds; however, the collected soil had by far the slowest taking almost 13 seconds for the water to penetrate through the soil.
· The topsoil had the least water holding capacity and released 26 mL which heavily contrasts with the collected soil which only released 7 mL.
· The topsoil's permeability was significantly higher than the other soils at 11.2 mL/second.
· The sand and the topsoil had the same pH of 6 where as the collected soil was slightly more acidic at a pH of 5.5.
Questions
1. The break down of the parts of your soil is shown in the soil triangle. Use the soil triangle to decide what type of soil the following are.
10% Clay, 60% Sand, and 30% Silt – Sandy Loam
60% Clay, 20% Sand, and 20% Silt - Clay
20% Clay, 20% Sand, and 60% Silt – Silt Loam
20% Clay, 40% Sand, and 40% Silt – Loam
2. Considering all the samples analyzed by your class in the first three parts, do you find any relationship between texture and consistence?
Yes, there is a major relationship between the texture and constancy. Sandy soil is always characterized by a very grainy texture and it doesn't mold when dampened. Clay has a very plastic like texture that gets very sticky and is easily molded when dampened. Silt has a much smoother texture than sand, but retains some of clays characteristics in its ability to mold.
3. How might the consistence of soil affect the growth of plants? Think about wet and dry conditions.
The consistence of soil affects the growth of plants by determining how much moisture is able to reach the plants roots. Soil that has a consistency of primarily clay will not be able to distribute an adequate amount of water to the plant. Clay has a very high water holding capacity and an extremely slow permeability. The water would get absorbed in the clay and not reach the roots. Soil that has a consistency leaning more towards sand and silt are much better suited to growing plants as more water can flow through the soil at a faster rate reaching the roots. In dry conditions, it is even more crucial for plants to receive adequate water. The consistency needs to be able to supply the plant with water by having an acceptable permeability.
4. Observe the other groups results for the water holding capacity. Was the capacity the same for all the soil sampled?
No, it was not. The water holding capacity of the clay was by far the largest. It only allowed 7 out of the fifty milliliters that was poured into the soil to escape. The sand had the second largest, allowing 19 mL of the total 50 mL to be released. The topsoil had the least water holding capacity and the water very quickly flowed through the soil releasing 26 mL.
5. What characteristic of soil is most important in determining water holding capacity?
The composition of the soil is the most important in determining the water holding capacity. Clay generally has a much higher water holding capacity than that of silt or sand because the particle size of the clay is much smaller allowing much less water to escape. Sand, in comparison, has very large particles which creates space that the water very easily flows out of.
6. Imagine a sloping field of very sandy soil and a sloping field of soil with very high clay content, each with an identical drainage ditch at the bottom. In a prolonged heavy downpour, do you think one ditch will be more likely to flood then the other? Why?
I think the sandy soil would be much less likely to flood than the clay soil. This is primarily because of the sandy soil’s permeability. Water flows much faster through sandy soil than it does through clay soil. The water would flow into the sandy soil and into the earth, thus, flooding more slowly. The clay soil would accumulate water much faster as the water would take much longer to flow through the soil.
7. If you have two fields of crops, one in which the soil was mostly sand and the other mostly clay, which would you have to water most often and why?
You would have to water the sandy soil most often. The sandy soil has a much lower water holding capacity than the clay soil. The sandy soil, therefore, wouldn’t hold as much water than the clay soil would so you’d need to water the clay soil more often to be sure the plants get a sufficient amount of water. This isn’t as much of a problem in the clay soil because the clay naturally holds more water.
8. Use the information you have collected about the local soil samples and suggest how this would affect agriculture and building in the area.
Based on the information, the local soil in the area is primarily clay based. Agriculture has both positives and negatives to having clay soil. The primary positive to having clay soil is that it holds moisture very well; however, the nature of clay makes roots very hard to grow and also causes very slow draining. The soil is also very slow to rise in temperature in the spring. Building a foundation on the soil has both its positives and negatives as well. An advantage is that it is relatively cheap compared to other common foundation material; however, water leakage and damage as well as pressure buildups are common issues that can plague construction.
Conclusion
My hypothesis was partly correct in some aspects, but incorrect in other aspects. The predictions for the soil compositions were generally correct. The sand and clay prediction were accurate; however, the prediction for the topsoil was wrong as it turned out to be loamy sand. The predictions for the pH were close, but not entirely accurate. It was predicted that the pH would be neutral for each of the soils; however, the pH turned out to be slightly acidic for each soil being around 5.5 to 6. The predications for the permeability were generally accurate. Clay had the slowest permeability because clays particle size is extremely small and allows very little water to escape. Sand had a much faster permeability than clay. This is because the particles of sand are much larger and allowed more space for the water to escape. The topsoil had by far the fastest permeability because like the sand the particle size enabled water to quickly flow through.
This experiment’s results were generally accurate; however, there were potential sources of error present. One source of error was the test to determine the soil’s composition. The chart was not particularly descriptive which made determining the composition fairly easy to make a mistake and come to the wrong conclusion about the soil quality. This was also the only test to determine soil composition so the composition may not be entirely accurate. When recording the permeability, only one trial was done. Having multiple trials and taking an average would enhance the lab in yielding a more accurate permeability.
This lab has many applications that can be applied in the real world, particularly in the subject of agriculture and construction. Knowing the soil composition of the ground allows agriculture to be much more successful. This lab proved that certain soil compositions retain more water than others. For example, clay retains much more water than that of sandy soil. This would be useful to know as knowing how much water to give a plant can be crucial to its growth. Being able to know just the soil’s composition allows the agriculture industry and recreational gardeners to grow plants at a much higher success rate. Knowing the soil is also crucial in the field of construction. Construction companies rely on knowing what type of soil they are building on as it could potentially be the difference between a safe and unsafe building. Clay also yields weathering problems pressure building which makes it crucial to these construction companies to know what soil they are building on.
Works cited:
"Soil Composition and Formation." Soil Composition and Formation. N.p., n.d. Web. 29 Nov. 2012. <http://www.nerrs.noaa.gov/doc/siteprofile/acebasin/html/envicond/soil/slform.htm>.
1. Define the following:
a. Porosity – the ability of a substance to absorb liquids.
b. Permeability – the quality of a substance that allows fluids or gases to pass through it.
c. Water holding capacity – amount of water that is available to plants in the soil.
d. Solution – a homogenous mixture of two substances.
e. Suspension – when small particles of a substance are dispersed throughout a gas or liquid.
2. What industries would find it important to know the structure of the soil?
The industries of agriculture, mining, construction, logging, and archeology would all find it important to know the structure of soil.
3. Using what you know about North Carolina now, would large scale use of septic tanks work well?
No, I don’t think the large scale use of septic tanks would work well at all. Generally, from my experience, the soil of North Carolina is primarily clay and not very permeable. If these large scale septic tanks were put into effect, I think it would not be broken down correctly and begin to ooze out of the ground.
Hypothesis:
If different tests are done to the different samples of soil, then the collected soil will be a sandy clay composition, a pH of 7 and not very permeable.
· Independent Variable: The soil used in the various tests.
· Dependent Variable: The composition, pH, and the permeability of the different types of soil.
· Controlled Variable: pH strip used, set up for permeability test
· Control: Topsoil & Sand
· Experimental: The soil collected
Problem: What is the composition, pH, and permeability of the collected soil, sand, and topsoil.
Materials
· Spray Bottles
· 3 Plastic Cups
· Rulers
· Wax Marker
· Soil Analysis Card
· Bag of Sand
· Bag of Clay
· Soil Sample
· Tap Water
· 4 Plastic Cylinders
· 4 Plastic Vials
· 4 Plastic Cups
· Cheesecloth
· Rubber Bands
· 60cc plastic medicine cups
· humus
· scissors
· balance
· Clock with Second Hand
· Twist Ties
Procedure
1. The first test is to determine the composition of the soil. First place a handful of the soil that needs to be tested in someone’s hand.
2. Moisten the soil. Follow the flow chart by answering the yes and no questions to determine the composition of the soil.
3. The pH test is performed by initially placing the soil being tested into a Petri dish.
4. Add water to the soil to create a mixture of water and soil.
5. Place the pH strip into the soil mixture and use the chart provided on the pH package to determine the pH of the soil.
6. The permeability test is done by initially setting up the cup on the stand so it is 1 inch above the beaker collecting the water.
7. Place 50 mL into a graduated cylinder.
8. Place the soil into the cup suspended into the stand and place a beaker below the cup to catch the water.
9. Pour the 50 mL of water that was in the graduated cylinder into the cup with the soil and begin timing as soon as water reaches the soil.
10. Continue to time until water comes through the soil and into the beaker. Measure the amount of water that was released into the beaker.
Observations:
· The collected local soil turned out to be sandy clay loam, the topsoil was concluded to be loamy sand, and the sand was sand.
· The topsoil had by far the fastest flow time taking only 2.33 seconds; however, the collected soil had by far the slowest taking almost 13 seconds for the water to penetrate through the soil.
· The topsoil had the least water holding capacity and released 26 mL which heavily contrasts with the collected soil which only released 7 mL.
· The topsoil's permeability was significantly higher than the other soils at 11.2 mL/second.
· The sand and the topsoil had the same pH of 6 where as the collected soil was slightly more acidic at a pH of 5.5.
Questions
1. The break down of the parts of your soil is shown in the soil triangle. Use the soil triangle to decide what type of soil the following are.
10% Clay, 60% Sand, and 30% Silt – Sandy Loam
60% Clay, 20% Sand, and 20% Silt - Clay
20% Clay, 20% Sand, and 60% Silt – Silt Loam
20% Clay, 40% Sand, and 40% Silt – Loam
2. Considering all the samples analyzed by your class in the first three parts, do you find any relationship between texture and consistence?
Yes, there is a major relationship between the texture and constancy. Sandy soil is always characterized by a very grainy texture and it doesn't mold when dampened. Clay has a very plastic like texture that gets very sticky and is easily molded when dampened. Silt has a much smoother texture than sand, but retains some of clays characteristics in its ability to mold.
3. How might the consistence of soil affect the growth of plants? Think about wet and dry conditions.
The consistence of soil affects the growth of plants by determining how much moisture is able to reach the plants roots. Soil that has a consistency of primarily clay will not be able to distribute an adequate amount of water to the plant. Clay has a very high water holding capacity and an extremely slow permeability. The water would get absorbed in the clay and not reach the roots. Soil that has a consistency leaning more towards sand and silt are much better suited to growing plants as more water can flow through the soil at a faster rate reaching the roots. In dry conditions, it is even more crucial for plants to receive adequate water. The consistency needs to be able to supply the plant with water by having an acceptable permeability.
4. Observe the other groups results for the water holding capacity. Was the capacity the same for all the soil sampled?
No, it was not. The water holding capacity of the clay was by far the largest. It only allowed 7 out of the fifty milliliters that was poured into the soil to escape. The sand had the second largest, allowing 19 mL of the total 50 mL to be released. The topsoil had the least water holding capacity and the water very quickly flowed through the soil releasing 26 mL.
5. What characteristic of soil is most important in determining water holding capacity?
The composition of the soil is the most important in determining the water holding capacity. Clay generally has a much higher water holding capacity than that of silt or sand because the particle size of the clay is much smaller allowing much less water to escape. Sand, in comparison, has very large particles which creates space that the water very easily flows out of.
6. Imagine a sloping field of very sandy soil and a sloping field of soil with very high clay content, each with an identical drainage ditch at the bottom. In a prolonged heavy downpour, do you think one ditch will be more likely to flood then the other? Why?
I think the sandy soil would be much less likely to flood than the clay soil. This is primarily because of the sandy soil’s permeability. Water flows much faster through sandy soil than it does through clay soil. The water would flow into the sandy soil and into the earth, thus, flooding more slowly. The clay soil would accumulate water much faster as the water would take much longer to flow through the soil.
7. If you have two fields of crops, one in which the soil was mostly sand and the other mostly clay, which would you have to water most often and why?
You would have to water the sandy soil most often. The sandy soil has a much lower water holding capacity than the clay soil. The sandy soil, therefore, wouldn’t hold as much water than the clay soil would so you’d need to water the clay soil more often to be sure the plants get a sufficient amount of water. This isn’t as much of a problem in the clay soil because the clay naturally holds more water.
8. Use the information you have collected about the local soil samples and suggest how this would affect agriculture and building in the area.
Based on the information, the local soil in the area is primarily clay based. Agriculture has both positives and negatives to having clay soil. The primary positive to having clay soil is that it holds moisture very well; however, the nature of clay makes roots very hard to grow and also causes very slow draining. The soil is also very slow to rise in temperature in the spring. Building a foundation on the soil has both its positives and negatives as well. An advantage is that it is relatively cheap compared to other common foundation material; however, water leakage and damage as well as pressure buildups are common issues that can plague construction.
Conclusion
My hypothesis was partly correct in some aspects, but incorrect in other aspects. The predictions for the soil compositions were generally correct. The sand and clay prediction were accurate; however, the prediction for the topsoil was wrong as it turned out to be loamy sand. The predictions for the pH were close, but not entirely accurate. It was predicted that the pH would be neutral for each of the soils; however, the pH turned out to be slightly acidic for each soil being around 5.5 to 6. The predications for the permeability were generally accurate. Clay had the slowest permeability because clays particle size is extremely small and allows very little water to escape. Sand had a much faster permeability than clay. This is because the particles of sand are much larger and allowed more space for the water to escape. The topsoil had by far the fastest permeability because like the sand the particle size enabled water to quickly flow through.
This experiment’s results were generally accurate; however, there were potential sources of error present. One source of error was the test to determine the soil’s composition. The chart was not particularly descriptive which made determining the composition fairly easy to make a mistake and come to the wrong conclusion about the soil quality. This was also the only test to determine soil composition so the composition may not be entirely accurate. When recording the permeability, only one trial was done. Having multiple trials and taking an average would enhance the lab in yielding a more accurate permeability.
This lab has many applications that can be applied in the real world, particularly in the subject of agriculture and construction. Knowing the soil composition of the ground allows agriculture to be much more successful. This lab proved that certain soil compositions retain more water than others. For example, clay retains much more water than that of sandy soil. This would be useful to know as knowing how much water to give a plant can be crucial to its growth. Being able to know just the soil’s composition allows the agriculture industry and recreational gardeners to grow plants at a much higher success rate. Knowing the soil is also crucial in the field of construction. Construction companies rely on knowing what type of soil they are building on as it could potentially be the difference between a safe and unsafe building. Clay also yields weathering problems pressure building which makes it crucial to these construction companies to know what soil they are building on.
Works cited:
"Soil Composition and Formation." Soil Composition and Formation. N.p., n.d. Web. 29 Nov. 2012. <http://www.nerrs.noaa.gov/doc/siteprofile/acebasin/html/envicond/soil/slform.htm>.
Data Chart
Data compiled from the various tests preformed on the soils.
Graph
Graph detailing the permeability of the different soils.
pH Test
pH Test of the different soils. Sand on far left, collected soil in center, topsoil on far right.
Permeability Test
Set-up for the permeability test
Soil Composition Test
Soil in the process of being identified