Soil Analysis Lab
Pre-Lab Questions:
1. Define:
-Porosity: space for air/liquid within a soil
-Permeability: ability of water to flow through a substance
-Water Holding Capacity: ability of a soil to hold water (inverse of porosity)
-Solution: molecules dissolved in a solvent
-Suspension: particles transported in water
2. What industries would find it important to know the structure of soil?
-Septic tank business, the agriculture industry, and the construction industry would find soil structure to be especially important.
3. Using what you know about North Carolina now, would large scale use of septic tanks work well?
-Large scale use of septic tanks would not bode well for us because our soil (clay) does not hold water well.
Hypothesis: The sand will have the greatest permeability because sand has the highest porosity. The distance between each particle will allow water to flow more easily. The independent variable is the type of soil. The dependent variables are the flow time and the amount of water recovered (and therefore, the permeability). The controlled variables include the amount of water poured through and the amount of soil in each cup. The control groups are the cups with pebbles instead of soil samples. The experimental groups are the cups with the soil samples.
Problem: Which type of soil will have the greatest permeability?
Materials:
-Spray Bottle
-3 Plastic Cups
-Rulers
-Wax Marker
-"Soil Texture by Feel" Flow Chart
-Bag of Sand/Clay/Silt
-Tap Water
-Plastic Cylinder
-Plastic Vial
-Plastic Cup
-Cheesecloth
-Rubber Band
-60cc plastic medicine cup
-humus
-scissors
-balance
-Timer
-Twist Ties
Procedure:
(each group)
1. Fill the spray bottle and use the "Soil Texture by Feel" flow chart to determine the type of soil of the soil sample.
2. Suspend the wet column with the soil sample in it about one inch above a graduated cylinder.
3. Put 50mL of water into a cup. Designate one member as the timekeeper and one as the recorder. When everyone is ready, pour the water onto the soil. The timer should time how long it takes until the first drop of water comes out of the bottom of the column and into the graduated cylinder. Set up a data table to record this information. Watch the column until there is not more water standing above the soil sample and no more dripping through the column. Record this time as well.
4. Determine the permeability and record.
5. Determine the amount of water recovered in the cup and record.
6. Compare results to other groups' soil samples to determine the most permeable substance.
Observations and Data:
Group 5
Soil Type: Sandy Loam
Flow Time: 65 seconds
Water Recovered: 40 mL (out of 50mL)
Permeability(mL/second): 0.625 mL/s
1. Define:
-Porosity: space for air/liquid within a soil
-Permeability: ability of water to flow through a substance
-Water Holding Capacity: ability of a soil to hold water (inverse of porosity)
-Solution: molecules dissolved in a solvent
-Suspension: particles transported in water
2. What industries would find it important to know the structure of soil?
-Septic tank business, the agriculture industry, and the construction industry would find soil structure to be especially important.
3. Using what you know about North Carolina now, would large scale use of septic tanks work well?
-Large scale use of septic tanks would not bode well for us because our soil (clay) does not hold water well.
Hypothesis: The sand will have the greatest permeability because sand has the highest porosity. The distance between each particle will allow water to flow more easily. The independent variable is the type of soil. The dependent variables are the flow time and the amount of water recovered (and therefore, the permeability). The controlled variables include the amount of water poured through and the amount of soil in each cup. The control groups are the cups with pebbles instead of soil samples. The experimental groups are the cups with the soil samples.
Problem: Which type of soil will have the greatest permeability?
Materials:
-Spray Bottle
-3 Plastic Cups
-Rulers
-Wax Marker
-"Soil Texture by Feel" Flow Chart
-Bag of Sand/Clay/Silt
-Tap Water
-Plastic Cylinder
-Plastic Vial
-Plastic Cup
-Cheesecloth
-Rubber Band
-60cc plastic medicine cup
-humus
-scissors
-balance
-Timer
-Twist Ties
Procedure:
(each group)
1. Fill the spray bottle and use the "Soil Texture by Feel" flow chart to determine the type of soil of the soil sample.
2. Suspend the wet column with the soil sample in it about one inch above a graduated cylinder.
3. Put 50mL of water into a cup. Designate one member as the timekeeper and one as the recorder. When everyone is ready, pour the water onto the soil. The timer should time how long it takes until the first drop of water comes out of the bottom of the column and into the graduated cylinder. Set up a data table to record this information. Watch the column until there is not more water standing above the soil sample and no more dripping through the column. Record this time as well.
4. Determine the permeability and record.
5. Determine the amount of water recovered in the cup and record.
6. Compare results to other groups' soil samples to determine the most permeable substance.
Observations and Data:
Group 5
Soil Type: Sandy Loam
Flow Time: 65 seconds
Water Recovered: 40 mL (out of 50mL)
Permeability(mL/second): 0.625 mL/s
Analysis and Conclusions:
Lab Questions:
1. 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?
-Those soils that were granular has a lesser consistency (like sand). Those that were smooth had a higher consistency.
3. How might the consistence of soil affect the growth of plants? Think about wet and dry conditions.
-If soil is very thick (has plate or blocky peds), it will hold water better. However, its thickness might not allow the roots to grow fully. If it is thin (has rounded peds), it will not hold water very well and it may not hold down the plant.
4. Observe the other groups results for the water holding capacity. Was the capacity the same for all the soil sampled?
-The capacity was not the same for each sample. The samples with clay held all of its water while the sandy loam held the least.
5. What characteristic of soil is most important in determining water holding capacity?
-The porosity of soil is the most important characteristic in determining water holding capacity.
6. Imagine a sloping field of very sandy soil and a sloping field of soil with a 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?
-The sloping field of high clay content would be more likely to flood because the soil would be more impermeable and therefore, absorb less of the water.
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 one with sand more often because its porosity would be greater, allowing the water to pass past the roots easily.
8. Use the information you have collected about the local soil samples and suggest how this would affect agriculture and building in the area.
-Our local soil, clay, puts a strain on both the agricultural and some building industries. Clay is quite impermeable which makes it a tough soil to grow crops in. Builders need to make sure the ground they build on will not be easily flooded due to clay's impermeability.
General Conclusions/Analysis:
The lab results did not completely support the hypothesis. According to the data, the sandy loam had the greatest permeability. This is probably due to the fact that the particles that made up the sandy loam were larger and more irregular with created a greater porosity. However, the data also alluded to the possibility of an error. One sample of sand had a permeability three times bigger than the other. This may have been due to errors in keeping the time or inaccurately picking the time when the water had stopped flowing into the cup. This lab helps determine which soils may or may not be best for certain situations. If the sample has a low permeability, it probably is not good for agriculture because the water will not reach the roots and it may cause flooding because it does not absorb much water. Knowing which type of soil is better to use can prevent incidents from happening before they occur (ruining crops, causing flooding).
Lab Questions:
1. 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?
-Those soils that were granular has a lesser consistency (like sand). Those that were smooth had a higher consistency.
3. How might the consistence of soil affect the growth of plants? Think about wet and dry conditions.
-If soil is very thick (has plate or blocky peds), it will hold water better. However, its thickness might not allow the roots to grow fully. If it is thin (has rounded peds), it will not hold water very well and it may not hold down the plant.
4. Observe the other groups results for the water holding capacity. Was the capacity the same for all the soil sampled?
-The capacity was not the same for each sample. The samples with clay held all of its water while the sandy loam held the least.
5. What characteristic of soil is most important in determining water holding capacity?
-The porosity of soil is the most important characteristic in determining water holding capacity.
6. Imagine a sloping field of very sandy soil and a sloping field of soil with a 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?
-The sloping field of high clay content would be more likely to flood because the soil would be more impermeable and therefore, absorb less of the water.
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 one with sand more often because its porosity would be greater, allowing the water to pass past the roots easily.
8. Use the information you have collected about the local soil samples and suggest how this would affect agriculture and building in the area.
-Our local soil, clay, puts a strain on both the agricultural and some building industries. Clay is quite impermeable which makes it a tough soil to grow crops in. Builders need to make sure the ground they build on will not be easily flooded due to clay's impermeability.
General Conclusions/Analysis:
The lab results did not completely support the hypothesis. According to the data, the sandy loam had the greatest permeability. This is probably due to the fact that the particles that made up the sandy loam were larger and more irregular with created a greater porosity. However, the data also alluded to the possibility of an error. One sample of sand had a permeability three times bigger than the other. This may have been due to errors in keeping the time or inaccurately picking the time when the water had stopped flowing into the cup. This lab helps determine which soils may or may not be best for certain situations. If the sample has a low permeability, it probably is not good for agriculture because the water will not reach the roots and it may cause flooding because it does not absorb much water. Knowing which type of soil is better to use can prevent incidents from happening before they occur (ruining crops, causing flooding).