Group 4 Science ProjectGroup 4 Science ProjectPhysics in the School Field:Physics in the School Field:

Soil TestsSoil TestsTeddy ThamrinTeddy ThamrinSpencer OngSpencer Ong

IntroductionIntroduction

• We chose the field because we heard that several We chose the field because we heard that several people using it have gotten injured after slipping.people using it have gotten injured after slipping.

• We also learned that the school was unhappy with the We also learned that the school was unhappy with the field’s conditions and was planning to rebuild it.field’s conditions and was planning to rebuild it.

• So we carried out several experiments to So we carried out several experiments to scientifically determine the suitability of our current scientifically determine the suitability of our current field.field.

• From the results of the experiment, we can then From the results of the experiment, we can then determine whether the field is indeed unsuitable and determine whether the field is indeed unsuitable and suggest ways to improve its safety and usability.suggest ways to improve its safety and usability.

PurposePurpose

• To find out the coefficient of static friction, To find out the coefficient of static friction, water absorption rate and compactibility of the water absorption rate and compactibility of the soil from different parts of the field, from the soil from different parts of the field, from the grassy areas to the completely bare clay grassy areas to the completely bare clay patches.patches.

• To determine the soil composition of the field To determine the soil composition of the field and suggest what kind of soil should be used and suggest what kind of soil should be used in the future.in the future.

HypothesisHypothesis

The characteristics of a good field are:The characteristics of a good field are:• high grip,high grip,• good drainage, good drainage, • low compactibilitylow compactibility• suitable for the growth of grasssuitable for the growth of grass

We predict that the field has none of these We predict that the field has none of these

characteristics. characteristics.

Part A: Soil Friction TestsPart A: Soil Friction Tests

• Many parts of the field, especially those that are Many parts of the field, especially those that are heavily used, are completely bare.heavily used, are completely bare.

• We wanted to see how much this affects the friction We wanted to see how much this affects the friction of the field and whether it was a safety concern.of the field and whether it was a safety concern.

• We also compared different parts of the field under We also compared different parts of the field under wet and dry conditions to determine how much the wet and dry conditions to determine how much the friction of the field is affected by rain.friction of the field is affected by rain.

Part A: MethodPart A: Method• Equipment – Shoe, Newton metre, 1kg Equipment – Shoe, Newton metre, 1kg

weightweight• First, we used a school shoe and put it onto First, we used a school shoe and put it onto

various parts of the field such as clay various parts of the field such as clay patches or grassy areas.patches or grassy areas.

• Using a Newton metre we measured the Using a Newton metre we measured the required force to start moving the shoe. We required force to start moving the shoe. We carefully increased the force on the shoe carefully increased the force on the shoe and recorded the final force when the shoe and recorded the final force when the shoe started moving.started moving.

• We put a 1kg mass in the centre of the shoe We put a 1kg mass in the centre of the shoe to make sure the pulling of the Newton to make sure the pulling of the Newton metre does not cause a lifting force which metre does not cause a lifting force which would cause less surface area to touch the would cause less surface area to touch the ground and give smaller results. ground and give smaller results.

• After that, we hosed the areas we tested After that, we hosed the areas we tested earlier with water to test the friction of the earlier with water to test the friction of the soil when it was wet.soil when it was wet.

From the results, the coefficient of static friction is calculated using this formula:

µ = f / N

Soil Friction Test ResultsSoil Friction Test Results

Soil TypeSoil Type

Force needed to move the shoe, F (N)Force needed to move the shoe, F (N) Coefficient of static Coefficient of static Friction, Friction, µµ

11 22 33 AverageAverage

Very grassyVery grassy 9.89.8 14.014.0 11.611.6 11.8 11.8 ± 1.7± 1.7 0.851 0.851 ± 0.123± 0.123

Patchy grassPatchy grass 10.210.2 9.69.6 9.19.1 9.6 9.6 ± 0.5± 0.5 0.692 0.692 ± 0.036± 0.036

ClayClay 6.06.0 6.76.7 5.25.2 6.0 6.0 ± 0.6± 0.6 0.433 0.433 ± 0.043± 0.043

Sandy ClaySandy Clay 7.27.2 5.85.8 6.26.2 6.4 6.4 ± 0.6± 0.6 0.462 0.462 ± 0.043± 0.043

Wet GrassyWet Grassy 8.08.0 8.08.0 7.07.0 7.7 7.7 ± 0.5± 0.5 0.555 0.555 ± 0.036± 0.036

Wet PatchyWet Patchy 7.07.0 7.27.2 7.87.8 7.3 7.3 ± 0.3± 0.3 0.526 0.526 ± 0.022± 0.022

Wet ClayWet Clay 6.26.2 5.85.8 6.06.0 6.0 6.0 ± 0.2± 0.2 0.433 0.433 ± 0.014± 0.014

Wet Sandy Wet Sandy ClayClay

4.24.2 4.44.4 6.06.0 4.9 4.9 ± 0.8± 0.8 0.353 0.353 ± 0.058± 0.058

Weight of Shoe + 1kg load, W = 13.867 ±± 0.0001N

Part A: Conclusion and EvaluationPart A: Conclusion and Evaluation• From our research, we found that an average 0.50* Coefficient From our research, we found that an average 0.50* Coefficient

of Static Friction is the minimum safety standard for a sports of Static Friction is the minimum safety standard for a sports surface. surface.

• The clay and sandy clay patches did not meet these standards The clay and sandy clay patches did not meet these standards especially when wet which decreases the coefficient of especially when wet which decreases the coefficient of friction.friction.

• The grassy patches on the other hand, had significantly higher The grassy patches on the other hand, had significantly higher grips and were above the safety standard even when wet.grips and were above the safety standard even when wet.

• The school should pick soil that is better for grass growth, so The school should pick soil that is better for grass growth, so if they rebuild the field, they should use less clay and try to if they rebuild the field, they should use less clay and try to use grass that can grow better in the field. They could also use use grass that can grow better in the field. They could also use a topsoil that has better traction and is better for grass growtha topsoil that has better traction and is better for grass growth

• To improve, we could have used sport shoes in our experiment To improve, we could have used sport shoes in our experiment to check if they would pass the standards that our school shoes to check if they would pass the standards that our school shoes did not. did not.

*Coeffiction of Static Friction Standards from: http://www.hazardcontrol.com/sliptrip.html; Credentials: http://www.hazardcontrol.com/gnelson.html

Part B: Water Absorption TestsPart B: Water Absorption Tests

• From part A, we found that water had quite a From part A, we found that water had quite a profound effect on the friction of the field, especially profound effect on the friction of the field, especially on the grassy parts. So, we decided to carry out tests on the grassy parts. So, we decided to carry out tests on how well the soil absorbs water.on how well the soil absorbs water.

• Water absorption is important because after it rains, Water absorption is important because after it rains, puddles of water are usually left on the field which, if puddles of water are usually left on the field which, if not drained, will leave the field slippery and not drained, will leave the field slippery and dangerous for a long period of time.dangerous for a long period of time.

• Also, if the field is flooded for too long the roots of Also, if the field is flooded for too long the roots of the grass will die* because they can’t respirate the grass will die* because they can’t respirate underwater, causing a reduction in grassy patches and underwater, causing a reduction in grassy patches and an increase in slippery clay patches.an increase in slippery clay patches.

*http://www.allaboutlawns.com/lawn-maintenance-care/watering/surviving-a-flood.php

Part B: MethodPart B: Method• Equipment – Measuring cylinder, Equipment – Measuring cylinder,

stopwatch, metre rulestopwatch, metre rule

• First, we filled the measuring First, we filled the measuring cylinder with water.cylinder with water.

• Then, we quickly overturned the Then, we quickly overturned the cylinder over the clay soil and cylinder over the clay soil and pressed it into the soilpressed it into the soil

• After that, we started the timer and After that, we started the timer and measured the volume of water.measured the volume of water.

• After an hour, we measured the After an hour, we measured the volume again and stopped the timer.volume again and stopped the timer.

• We repeated the experiment for We repeated the experiment for sandy clay, patchy grass and heavy sandy clay, patchy grass and heavy grass areas.grass areas.

Soil Water Absorption TestsSoil Water Absorption TestsSoilSoil

TypeType

Starting Starting Volume Volume

(ml)(ml)

End End Volume Volume

(ml)(ml)

Difference Difference (ml)(ml)

Time Time (hours)(hours)

Drainage Drainage raterate

(ml/hour)(ml/hour)

Drainage rate Drainage rate (cm/hour)(cm/hour)

ClayClay 330 330 ± 5± 5 290 290 ± 5± 5 40 40 ± 10± 10 1:011:01 39.34 39.34 ± ± 25%25%

1.39 1.39 ± 0.4± 0.4

Sandy Sandy ClayClay

550 550 ± 5± 5 450 450 ± 5± 5 100 100 ± 10± 10 1:001:00 100.00 100.00 ± ± 10%10%

3.54 3.54 ±± 0.4 0.4

Full Full GrassGrass

360 360 ± 5± 5 250 250 ± 5± 5 110 110 ± 10± 10 0:300:30 220.00 220.00 ± ± 9%9%

7.78 7.78 ±± 0.8 0.8

Patchy Patchy GrassGrass

300 300 ± 5± 5 230 230 ± 5± 5 70 70 ± 10± 10 1:001:00 70.00 70.00 ± ± 14%14%

2.48 2.48 ±± 0.4 0.4

Tube diameter = 6cm ± 0.1cm± 0.1cm

Part B: Conclusion and EvaluationPart B: Conclusion and Evaluation• From our results, we found that bare clay soil has very poor while areas with lots From our results, we found that bare clay soil has very poor while areas with lots

of grass or sand tend to have slightly higher drainage rates.of grass or sand tend to have slightly higher drainage rates.

• However, from our research good sports fields usually have a drainage rate of 12-However, from our research good sports fields usually have a drainage rate of 12-25 cm/hour. All our soil samples were substantially lower than this, even within 25 cm/hour. All our soil samples were substantially lower than this, even within error.error.

• A solution to this would be to use more sand when rebuilding the field or to add a A solution to this would be to use more sand when rebuilding the field or to add a soil conditioner to the field like ceramic grains to improve drainage. A gradient soil conditioner to the field like ceramic grains to improve drainage. A gradient could also be added to the field so that excess water would not stagnate but flow could also be added to the field so that excess water would not stagnate but flow off quickly to the sides.off quickly to the sides.

• The results could have been improved by drilling a hole into the ground to test the The results could have been improved by drilling a hole into the ground to test the drainage more accurately. However, we didn’t have the proper equipment and drainage more accurately. However, we didn’t have the proper equipment and didn’t want to damage the field. didn’t want to damage the field.

• During the monsoon seasons, such as in October that had 383mm of rain for the During the monsoon seasons, such as in October that had 383mm of rain for the whole month, the field will be water-logged for around 30 minutes every day whole month, the field will be water-logged for around 30 minutes every day since most of the field is clayish. since most of the field is clayish.

Part C: Soil Compaction TestsPart C: Soil Compaction Tests

• Another important factor that can affect the field is soil Another important factor that can affect the field is soil compactibility. If the soil is not compactible enough, it will compactibility. If the soil is not compactible enough, it will easily be displaced and the field would end up very lumpy.easily be displaced and the field would end up very lumpy.

• On the other hand, if the soil is overly compacted, the roots of On the other hand, if the soil is overly compacted, the roots of the grass cannot respirate properly as there will be little air in the grass cannot respirate properly as there will be little air in the ground. Highly compacted soil also makes it difficult for the ground. Highly compacted soil also makes it difficult for new grass to grow as it is hard to penetrate.new grass to grow as it is hard to penetrate.

• Other than that, highly compacted soil has worse drainage Other than that, highly compacted soil has worse drainage since there is less space between soil particles for water to since there is less space between soil particles for water to flow through. Compacted soil is also quite hard and can cause flow through. Compacted soil is also quite hard and can cause worse injuries compared to uncompacted soil.worse injuries compared to uncompacted soil.

Part C: MethodPart C: Method• Equipment – 1 litre Plastic measuring Equipment – 1 litre Plastic measuring

cup, 2kg cylindrical weight, digital cup, 2kg cylindrical weight, digital weighing scalesweighing scales

• First, we collected 4 soil samples from 4 First, we collected 4 soil samples from 4 different parts of the field: dry clay, different parts of the field: dry clay, sandy clay, clay from patchy grassy sandy clay, clay from patchy grassy areas and clay from grassy areas.areas and clay from grassy areas.

• We then removed all foreign objects, We then removed all foreign objects, grass and roots from the samples.grass and roots from the samples.

• We shuffled and shook the sample to We shuffled and shook the sample to loosen the soil and record the initial loosen the soil and record the initial volume and mass of the soil.volume and mass of the soil.

• Next, we compacted the soil sample Next, we compacted the soil sample using a cylindrical weight for around 5 using a cylindrical weight for around 5 minutes. The new volume of the soil minutes. The new volume of the soil was then recorded.was then recorded.

• We calculated the density of the sample We calculated the density of the sample before and after compaction and found before and after compaction and found the percentage difference.the percentage difference.

• We repeated this for the other 3 samples.We repeated this for the other 3 samples.

Soil Compaction TestsSoil Compaction Tests

Soil TypeSoil Type Volume (cmVolume (cm33)) Soil Soil Mass Mass (g)(g)

Density (g/cmDensity (g/cm33)) CompactionCompaction

(%)(%)StartStart EndEnd StartStart EndEnd

Dry ClayDry Clay 210 210 ± 5± 5 130 130 ± 5± 5 232 232 ± ± 0.010.01

1.10 1.10 ± ± 2%2%

1.78 1.78 ± 4%± 4% 61.82 61.82 ± 3.71± 3.71

Sandy ClaySandy Clay 400 400 ± 5± 5 330 330 ± 5± 5 480 480 ± ± 0.010.01

1.2 1.2 ± 1%± 1% 1.45 1.45 ± 2%± 2% 20.83 20.83 ± 0.62± 0.62

Damp Damp Grassy SoilGrassy Soil

490 490 ± 5± 5 360 360 ± 5± 5 483 483 ± ± 0.010.01

0.99 0.99 ± ± 1%1%

1.34 1.34 ± 1%± 1% 35.35 35.35 ± 0.71± 0.71

Wet Grassy Wet Grassy SoilSoil

410 410 ± 5± 5 260 260 ± 5± 5 488 488 ± ± 0.010.01

1.12 1.12 ± ± 1%1%

1.88 1.88 ± 2%± 2% 67.86 67.86 ± 2.04± 2.04

Part C: Conclusion and EvaluationPart C: Conclusion and Evaluation

• From our results, we can see that clay soil is very compactable, From our results, we can see that clay soil is very compactable, especially when it has a high moisture content. However, with the especially when it has a high moisture content. However, with the presence of sand it was less compactable.presence of sand it was less compactable.

• From our research, good field soil has a bulk density of 1.4–1.6 From our research, good field soil has a bulk density of 1.4–1.6 g/g/cmcm33. Only the sandy clay was within this range. We also found . Only the sandy clay was within this range. We also found from a golf course site that even a 10% reduction in air space can from a golf course site that even a 10% reduction in air space can impact grass growth.impact grass growth.

• We can already see this problem in the field as the highly used parts We can already see this problem in the field as the highly used parts of the field, which have been compacted to a high degree by the of the field, which have been compacted to a high degree by the students, are noticeably bare while the fringes of the field still have students, are noticeably bare while the fringes of the field still have adequate grass coverage.adequate grass coverage.

• To improve the field more sand could be used or someone could be To improve the field more sand could be used or someone could be employed to aerate the soil frequently although it is costly.employed to aerate the soil frequently although it is costly.

• The experiment could be improved by using professional soil testing The experiment could be improved by using professional soil testing equipment like a penetrometer.equipment like a penetrometer.

Part D: Soil Texture AnalysisPart D: Soil Texture Analysis

• In this final test, we tried to determine the soil In this final test, we tried to determine the soil texture of the field, which is determined by the texture of the field, which is determined by the ratio of the different aggregates in the soil: ratio of the different aggregates in the soil: clay, silt and sand.clay, silt and sand.

• From the results, we can then determine which From the results, we can then determine which aggregates should be increased and decreased aggregates should be increased and decreased and roughly by how much when repairing the and roughly by how much when repairing the field.field.

Part D: MethodPart D: MethodEquipment – Beaker, detergent, jar, soil Equipment – Beaker, detergent, jar, soil

samplesample1) Pour soil into a beaker until it fills up 1) Pour soil into a beaker until it fills up

one-third of the beaker.one-third of the beaker.2) Pour in water till two third of the beaker 2) Pour in water till two third of the beaker

is filled. Add in a bit of detergent to is filled. Add in a bit of detergent to help break up the soil.help break up the soil.

3) Pour the mixture into a jar, close the jar 3) Pour the mixture into a jar, close the jar and shake vigorously for 30 seconds. and shake vigorously for 30 seconds. After this, quickly pour it back into the After this, quickly pour it back into the beaker.beaker.

4) Leave the soil in the beaker to settle for 4) Leave the soil in the beaker to settle for a week.a week.

5) Measure the height of each individual 5) Measure the height of each individual aggregate layer and determine the aggregate layer and determine the percentage of each aggregates.percentage of each aggregates.

6) Determine the soil texture type by 6) Determine the soil texture type by comparing it to a soil texture triangle.comparing it to a soil texture triangle.

Soil Texture Analysis ResultsSoil Texture Analysis Results

AggregateAggregate Percentage (%)Percentage (%)

ClayClay 3131

SiltSilt 4949

SandSand 2020

Part D: Conclusion and AnalysisPart D: Conclusion and Analysis

• By using the soil texture triangle below we determined that the soil in our field is By using the soil texture triangle below we determined that the soil in our field is called silty clay loam.called silty clay loam.

• However, the soil sample that was taken came from the surface of the field and However, the soil sample that was taken came from the surface of the field and might not be a perfect representation of the actual soil composition of the field.might not be a perfect representation of the actual soil composition of the field.

• Furthermore, the method used for determining the soil composition is quite crude. Furthermore, the method used for determining the soil composition is quite crude. To more accurately determine the soil composition, a sample should be sent to a lab To more accurately determine the soil composition, a sample should be sent to a lab where they have the proper equipment like centrifuges. where they have the proper equipment like centrifuges.

• From our research we found that most sports fields including From our research we found that most sports fields including

football fields and baseball pitches use a soil football fields and baseball pitches use a soil

composition of 60-80% sand with the remaining composition of 60-80% sand with the remaining

silt and clay in 2:1 ratio. From the triangle, thatsilt and clay in 2:1 ratio. From the triangle, that

soil would be sandy loam.soil would be sandy loam.

Diagram from: http://web.ukonline.co.uk/fred.moor/soil/formed/f0107.htm

Environmental ImpactEnvironmental Impact

• None of our experiments really impacted the None of our experiments really impacted the environment.environment.

• All of our soil samples were taken from low-All of our soil samples were taken from low-traffic areas such as near the sides and some of traffic areas such as near the sides and some of the soil samples were returned after the the soil samples were returned after the experiment.experiment.

• The water retention cylinders were also placed The water retention cylinders were also placed in low-traffic areas as it required some time to in low-traffic areas as it required some time to have results.have results.

Overall Conclusion and EvaluationOverall Conclusion and Evaluation

• The field has been built using the wrong soil composition. The field has been built using the wrong soil composition. This resulted in high compactibility and bad drainage which is This resulted in high compactibility and bad drainage which is not suitable for grass growth. It also has low grip which is not suitable for grass growth. It also has low grip which is dangerous for students running on the field, especially without dangerous for students running on the field, especially without the right shoes. All of these results agreed with our hypothesis.the right shoes. All of these results agreed with our hypothesis.

• If the school rebuilds the field, they should use soil with a If the school rebuilds the field, they should use soil with a lower clay content and more sand which wouldn’t have these lower clay content and more sand which wouldn’t have these inherent problems. They could also use a topsoil although this inherent problems. They could also use a topsoil although this wouldn’t solve the drainage issue and only improve the grip.wouldn’t solve the drainage issue and only improve the grip.

• The experiment could also be improved by using more The experiment could also be improved by using more sophisticated equipment and methods such as drilling and sophisticated equipment and methods such as drilling and centrifuging which would have yielded more accurate results. centrifuging which would have yielded more accurate results. If we had more time, we could have also carried out the same If we had more time, we could have also carried out the same experiments on other fields.experiments on other fields.

BibliographyBibliography

Fred Moor, 1998, Soil Texture Triangle Diagram, http://web.ukonline.co.uk/fred.moor/soil/formed/f0107.htm [26th April 2007]

Nelson & Associates, 2007, “Slip and Trip Type Falls”, http://www.hazardcontrol.com/sliptrip.html;

Credentials: http://www.hazardcontrol.com/gnelson.html [26th April 2007]

Alex Russel, 2007, “Surviving a Flood”, http://www.allaboutlawns.com/lawn-maintenance-care/watering/surviving-a-flood.php [26th April 2007]

Malaysian Environment Agency, “Regional Weather in Malaysia” Malaysian Environment Agency, “Regional Weather in Malaysia” http://app.nea.gov.sg/cms/htdocs/article.asp?pid=1106http://app.nea.gov.sg/cms/htdocs/article.asp?pid=1106

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