background information
Soil is mainly composed of five different components which are, minerals, gas, water, microorganisms and organic matter. Minerals consists of primary minerals and secondary minerals. Primary minerals in soil are the sand and silt, while the secondary mineral is clay.The gas occupies some of the space in the soil volume. Oxygen helps the root and microbe respiration, which supports plant growth. Carbon dioxide and nitrogen are important for below ground plant functions, like nitrogen-fixing bacteria. Water in the soil make up 2% to 50% of the soil because they transport the nutrients for the plants and soil organisms, as well as facilitating biological and chemical decomposition. The microorganisms make up less than 1% of the soil. The organic matter consists of dead plants and animals, which provide elements and water for plant growth. At the depth of 15 cm to 30 cm beneath ground level, the soil contains a layer known as sandy loam, which is normally made out of sand and varying amount of silt and clay. When the soil is mixed with water to determine the different components, the clay is at the top, followed by the silt and the sand is at the bottom.
purposeTo determine the different components of soil at the depths of 10 cm, 20 cm and 30 cm, in the water reservoir area. |
HypothesisThe deeper the depth of the soil, the more sand, silt and clay will be presented. The soil at a depth of 10 cm below ground level is considered as the surface, whereas the depth of the soil at 20 cm to 30 cm below ground level are considered to be a dense-compacted layer called the sandy loam, which are made out of sand and a varying amount of silt and clay. |
Variables
Independent Variable: depth of soil (10 cm, 20 cm, and 30 cm)
Dependent Variable: components of soil
Controlled Variable: mass of soil and location
Independent Variable: depth of soil (10 cm, 20 cm, and 30 cm)
Dependent Variable: components of soil
Controlled Variable: mass of soil and location
Materials
- PVC pipe - 50 mm x 400 mm and 55 mm x 400 mm
- 30 cm Ruler
- Six dirt sample collecting tubes
- Seven 50 ml graduated cylinders
- Marker
- Masking tape
- Gloves
- Safety glasses
- Lab coats
- Stirring rod
- Weighing balance
- Six size 10 stoppers
- Tweezers
- Hammer
- Diluted water
- Six plastic weighing boats
Method
Collection of soil sample:
- Collect the dirt sample from two different locations, one near the canal and another near the water outlet at the Nongbon reservoir.
- Get the PVC 55 mm x 400 mm and using a permanent marker and a ruler, label 10 cm, 20 cm and 30 cm onto the pipe.
- Choose an area near the canal and hammer the PVC 55 mm x 400 mm pipe into the soil at a depth of 10 cm.
- Pull the PVC 55 mm x 400 mm pipe out, and use the PVC 50 mm x 400 mm to push out the soil collected, and put the soil sample into the soil sample collecting tube.
- Use the masking tape and permanent marker to label each of the soil sample collecting tubes.
- With the same location, do steps three to four with the 20 cm and 30 cm of depth.
- After doing these for the location near the canal, go to the location near the water outlet at the Nongbon reservoir.
- Using the same PVC 55 mm x 400 mm, which has the labels, do steps three to six for the location near the canal and collect it for the same depths of 10 cm, 20 cm and 30 cm.
- First wear safety glasses, a lab coat and gloves to protect yourself during the experiment.
- Using the weighing balance, measure out 17 grams of the soil collected from location one (near the canal) with a depth of 10cm, and put it in a 50 ml graduated cylinder.
- The get another 50 ml graduated cylinder and measure out 50 ml of diluted water and pour it into the graduated cylinder with the soil sample.
- Stir it with a stirring rod to break down the soil.
- Close it with a stopper and start shaking it for 5 minutes.
- Remove the stopper and let the solution sit for a day until the different ratios of the components of the soil start to separate.
- Do steps two to six with all the 20cm and 30 cm depths of the soil sample for location one (near the canal), as well as the other depth soil samples (10cm, 20cm, 30cm) collected from location two (near the water outlet).
- After one day, observe and record the ratio of the components presented in the solution.
DAta table
Line graph #1 |
Line graph #2 |
Conclusion
The hypothesis was rejected because based on the observations, at a depth of 10 cm, there is more clay, silt and sand, while at a depth of 30 cm, there is less components of clay sand and silt. In location 1, at a depth of 10 cm, the water percentage was 41.9%, the clay was 37.43%, the silt was 7.26% and the sand and gravel was 13.41%. At depth of 30 cm, there was 61.21% of water, 19.67% of clay, 5.46% of silt and 13.66% of sand and gravel. This depicts that there is a higher percentage of components present at a small depth of 10 cm, but at a deeper depth of 30 cm, there is a smaller percentage of the components present. There is also a large water percentage as the depth of the soil gets deeper. This could be because the organisms or plant growth need the nutrients from the water. The location of where the soil sample was from does not make a big difference. In location 2, at a depth of 10 cm, the water was 41.81%, the clay was 37.74, the silt was 7.13% and the sand and gravel was 13.32%. This delineates that there was not much of a difference with location 1 and 2 as the results were very similar. This might be because the locations were not very far from each other, and being next to the canal or the water outlet did not make a difference to the type of soil. The soil was still close to the presence of water, therefore the soils are not very different.
Evaluation
Strengths:
One of the strengths of the experiment was collecting the soil samples based on the different depths. Using the PVC 55 mm x 400 mm pipe with the labels made the process a lot faster because it was easy to identify the depth of the soil and knowing when to stop collecting the soil.
Weaknesses:
One limitation in this experiment is that separation between different components in the soil do not have clear differences. The sand and silt share similar colour, therefore, make it difficult to distinguish the different layers accurately. As a result, the ratio calculated may not be totally accurate and precise.
Improvements:
As there are several limitations to the experiment, improvements can be made. We can further differentiate the soil components through exposure to heat in order to decrease the humidity of the soil which will allow them to separate better in water. The container can also be improved further, the container could be bigger and wider to enable effective stirring therefore further improve the disassociation of water.
One of the strengths of the experiment was collecting the soil samples based on the different depths. Using the PVC 55 mm x 400 mm pipe with the labels made the process a lot faster because it was easy to identify the depth of the soil and knowing when to stop collecting the soil.
Weaknesses:
One limitation in this experiment is that separation between different components in the soil do not have clear differences. The sand and silt share similar colour, therefore, make it difficult to distinguish the different layers accurately. As a result, the ratio calculated may not be totally accurate and precise.
Improvements:
As there are several limitations to the experiment, improvements can be made. We can further differentiate the soil components through exposure to heat in order to decrease the humidity of the soil which will allow them to separate better in water. The container can also be improved further, the container could be bigger and wider to enable effective stirring therefore further improve the disassociation of water.