Pre-Lab
1. Define the following:
a. Porosity – having minute spaces or holes through which liquid or air may pass.
b. Permeability – the state or quality of a material or membrane that causes it to allow liquids or gases to pass through it.
c. Water holding capacity – Field capacity is the amount of soil moisture or water content held in soil after excess water has drained away and the rate of downward movement has materially decreased, which usually takes place within 2–3 days after a rain or irrigation in pervious soils of uniform structure and texture.
d. Solution – a liquid mixture in which the minor component (the solute) is uniformly distributed within the major component (the solvent).
e. Suspension – a mixture in which particles are dispersed throughout the bulk of a fluid
2. What industries would find it important to know the structure of the soil?
The agriculture, textile, and food industries would find it important to know the structure of the soil.
3. Using what you know about North Carolina now, would large scale use of septic tanks work well?
No, because NC’s soil is clay. This impermeability would cause septic fluid to ooze out of the ground.
a. Porosity – having minute spaces or holes through which liquid or air may pass.
b. Permeability – the state or quality of a material or membrane that causes it to allow liquids or gases to pass through it.
c. Water holding capacity – Field capacity is the amount of soil moisture or water content held in soil after excess water has drained away and the rate of downward movement has materially decreased, which usually takes place within 2–3 days after a rain or irrigation in pervious soils of uniform structure and texture.
d. Solution – a liquid mixture in which the minor component (the solute) is uniformly distributed within the major component (the solvent).
e. Suspension – a mixture in which particles are dispersed throughout the bulk of a fluid
2. What industries would find it important to know the structure of the soil?
The agriculture, textile, and food industries would find it important to know the structure of the soil.
3. Using what you know about North Carolina now, would large scale use of septic tanks work well?
No, because NC’s soil is clay. This impermeability would cause septic fluid to ooze out of the ground.
Parts of the Experiment
Independent Variable: different soils
Dependent Variable: soil composition, pH, permeability
Controlled Variable: volume of soil used, volume of water added
Control Groups: sand, topsoil
Experimental Groups: varying soils
Dependent Variable: soil composition, pH, permeability
Controlled Variable: volume of soil used, volume of water added
Control Groups: sand, topsoil
Experimental Groups: varying soils
Problem
Which soil composition will have the greatest permeability and pH?
Hypothesis
If different soil compositions were collected and tested for permeability and pH, then the sample composed of sand will have the greatest permeability and most neutral pH
Materials List
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
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. Take a bit of soil sample and moisten it.
2. Roll it in your hand use the questions to determine what the soil composition is.
3. Place soil into petri dish and add water to create a mixture
4. Measure the pH with pH paper.
5. Set up the plastic cup 1 inch above the beaker (use the stand to make this happen)
6. Put soil sample into the cup and fasten the cheesecloth
7. Pour 50 mL of water into the cup and let the water drip into the beaker below
8. Measure the amount of time it takes for the water to pass through the soil and fill the beaker below.
9. Repeat for the topsoil and sand samples
2. Roll it in your hand use the questions to determine what the soil composition is.
3. Place soil into petri dish and add water to create a mixture
4. Measure the pH with pH paper.
5. Set up the plastic cup 1 inch above the beaker (use the stand to make this happen)
6. Put soil sample into the cup and fasten the cheesecloth
7. Pour 50 mL of water into the cup and let the water drip into the beaker below
8. Measure the amount of time it takes for the water to pass through the soil and fill the beaker below.
9. Repeat for the topsoil and sand samples
Observations
- The topsoil had the least water holding capacity
- The collected soil had the greatest water holding capacity
- All of the soil samples had a pH of 6
- The collected soil had the greatest water holding capacity
- All of the soil samples had a pH of 6
Data Tables and Graphs
Analysis and Conclusions
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, a relationship is found between texture and consistency. Typically, sand is fine and grainy, silt is smooth and powder-like, and clay is hard and ungiving.
3. How might the consistence of soil affect the growth of plants? Think about wet and dry conditions.
First, plants would have a hard time growing in soil that consists of clay because the roots would not be able to penetrate the soil easily and the permeability is low; the water holding capacity is the greatest, however. Next, plants would have an okay time growing in sand because the roots would be able to grow easily and the sand would hold a fair amount of water; the nutrients would wash away too easily, however. Finally, the plants would have the best luck growing in silt because, again, the roots would grow easily and the silt can hold a good amount of water; the nutrients would be retained in the silt, as well.
4. Observe the other groups results for the water holding capacity. Was the capacity the same for all the soil sampled?
The capacity for all of the groups was not the exact same, however, the general idea was the same: clay holds the most water and the sand holds the second most; this depends entirely on the collected soil, however.
5. What characteristic of soil is most important in determining water holding capacity?
The composition of the soil is the greatest factor in determining water holding capacity.
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?
In a prolonged downpour, the clay ditch would be more likely to flood because, even though the clay has the best water holding capacity, it has the lowest permeability. The sand would allow the water to pass through it, when the clay would not.
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 the most often because it has the higher permeability. The sandy soil would allow the water pass through it easily, getting sucked up by the crops and passing to deeper layers of the sand. The clay, however would hold the water the longest, without letting it pass to the deeper layers.
8. Use the information you have collected about the local soil samples and suggest how this would affect agriculture and building in the area.
The collected soil samples indicate that the local soil is primarily clay. This hurts agriculture, because not many crops would be able to grow efficiently in soil that consists of clay. The clay would help the building industry, however. The low permeability of the clay results in a shallow frost line, therefore foundations would not have to go as deep into the ground.
Conclusion
My hypothesis was completely incorrect. The sand did not have the greatest permeability, the topsoil did; and the sand did not have the most neutral pH, all of the pH's were the same. The results of the experiment may have been affected with the way the soil was packed into the plastic cup. In the experiment, the topsoil was poured into the cup and packed only slightly so it was at the line; it was still very loose however. The sand was easily poured to the line, with no packing. The collected soil, however, was the most difficult to get to the line on the cup, because the soil was mostly clay. As a result, the collected soil was hard to pour, so it was packed pretty tightly into the plastic cup as a result. The results of this lab are applicable to the agriculture, construction, furniture, and textile industries alike. What is common among these is that they are dependent on soil quality. The agriculture and textile industries rely on quality soil to grow the crops that are needed for production. The construction industry relies on the soil permeability to help determine how deep the foundation must be placed (below the frost line). The furniture industry needs soil that can support trees and the plants used for the production of furniture and finishes. Though we may just think of it as dirt, soil has a profound impact on our economy, and to an extent, our lives.
Works cited: "Sand, Silt, Clay." Tomato Lover Sand Silt Clay Comments. N.p., n.d. Web. 11 Dec. 2012.
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, a relationship is found between texture and consistency. Typically, sand is fine and grainy, silt is smooth and powder-like, and clay is hard and ungiving.
3. How might the consistence of soil affect the growth of plants? Think about wet and dry conditions.
First, plants would have a hard time growing in soil that consists of clay because the roots would not be able to penetrate the soil easily and the permeability is low; the water holding capacity is the greatest, however. Next, plants would have an okay time growing in sand because the roots would be able to grow easily and the sand would hold a fair amount of water; the nutrients would wash away too easily, however. Finally, the plants would have the best luck growing in silt because, again, the roots would grow easily and the silt can hold a good amount of water; the nutrients would be retained in the silt, as well.
4. Observe the other groups results for the water holding capacity. Was the capacity the same for all the soil sampled?
The capacity for all of the groups was not the exact same, however, the general idea was the same: clay holds the most water and the sand holds the second most; this depends entirely on the collected soil, however.
5. What characteristic of soil is most important in determining water holding capacity?
The composition of the soil is the greatest factor in determining water holding capacity.
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?
In a prolonged downpour, the clay ditch would be more likely to flood because, even though the clay has the best water holding capacity, it has the lowest permeability. The sand would allow the water to pass through it, when the clay would not.
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 the most often because it has the higher permeability. The sandy soil would allow the water pass through it easily, getting sucked up by the crops and passing to deeper layers of the sand. The clay, however would hold the water the longest, without letting it pass to the deeper layers.
8. Use the information you have collected about the local soil samples and suggest how this would affect agriculture and building in the area.
The collected soil samples indicate that the local soil is primarily clay. This hurts agriculture, because not many crops would be able to grow efficiently in soil that consists of clay. The clay would help the building industry, however. The low permeability of the clay results in a shallow frost line, therefore foundations would not have to go as deep into the ground.
Conclusion
My hypothesis was completely incorrect. The sand did not have the greatest permeability, the topsoil did; and the sand did not have the most neutral pH, all of the pH's were the same. The results of the experiment may have been affected with the way the soil was packed into the plastic cup. In the experiment, the topsoil was poured into the cup and packed only slightly so it was at the line; it was still very loose however. The sand was easily poured to the line, with no packing. The collected soil, however, was the most difficult to get to the line on the cup, because the soil was mostly clay. As a result, the collected soil was hard to pour, so it was packed pretty tightly into the plastic cup as a result. The results of this lab are applicable to the agriculture, construction, furniture, and textile industries alike. What is common among these is that they are dependent on soil quality. The agriculture and textile industries rely on quality soil to grow the crops that are needed for production. The construction industry relies on the soil permeability to help determine how deep the foundation must be placed (below the frost line). The furniture industry needs soil that can support trees and the plants used for the production of furniture and finishes. Though we may just think of it as dirt, soil has a profound impact on our economy, and to an extent, our lives.
Works cited: "Sand, Silt, Clay." Tomato Lover Sand Silt Clay Comments. N.p., n.d. Web. 11 Dec. 2012.