Abstract:
This lab allowed us to test erosion on grass, leaf litter, and loose soil. Each of these were placed in two litter bottles with one side cut off. 500 mL of water was pored to the rear of the bottle while it will at an angle. This simulated water moving down a hill where erosion is most likely to happen. As expected, the bottle with grass lost the least amount of water, followed by the leaf litter, and finally the loose soil.
Problem:
How does having just grass, leaf litter, or nothing effect the amount of damage caused by erosion?
Hypothesis:
The grass will have a lower amount of soil erosion than leaf litter and loose soil.
Materials:
Methods:
Sowing the seeds
Data: (Pictures not to scale; different sized beakers were used)
This lab allowed us to test erosion on grass, leaf litter, and loose soil. Each of these were placed in two litter bottles with one side cut off. 500 mL of water was pored to the rear of the bottle while it will at an angle. This simulated water moving down a hill where erosion is most likely to happen. As expected, the bottle with grass lost the least amount of water, followed by the leaf litter, and finally the loose soil.
Problem:
How does having just grass, leaf litter, or nothing effect the amount of damage caused by erosion?
Hypothesis:
The grass will have a lower amount of soil erosion than leaf litter and loose soil.
Materials:
- 3 two litter bottles
- potting soil
- grass seeds
- Beakers
- Large Graduated Cylinder
- Water
- Pebbles, gravel or leaf litter
Methods:
Sowing the seeds
- Place soil in an empty 2L bottle that has been cut in half (see picture above). Spread grass seed evenly throughout the soil
- Water grass seed every 3-4 days and allow it to sit near a source of sunlight or under a plant grow lamp.
- When the grass has grown 2-4 inches in height, you are ready to test the effects.
- Fill two more empty 2L bottles with soil. Cover one with a top cover of your choice (gravel, pebbles, or leaf litter) and leave the other one alone as a control.
- Line the three bottles up on top of an elevated surface. Place an empty beaker underneath the mouth of each bottle.
- Prepare 4 graduated cylinders with 100 mL of water in each.
- Have a student start a timer and say “GO.” When the timer says go, all 3 graduated cylinders should be poured onto the soil bottles.
- Record the time, amount, and color of the water discharge in the table below. Then, answer the questions.
Data: (Pictures not to scale; different sized beakers were used)
Bottle:
Grass Ground Cover Soil |
Water Collected (mL): (% Return)
255 51% 325 65% 420 84% |
Water Stop Time (mm:ss):
3:37 2:40 3:00 |
Qualitative Data:
Light Brownk; little suspension Medium Brown; Medium suspension Dark Brown; Heavy suspension |
Lab Specific Conclusions:
General Conclusion:
This lab has allowed us to understand how erosion works. It now makes sense that soil held together by some rooted plant is the best way to prevent erosion. This experiment proved my hypothesis to be true. National Geographic says that "Erosion transports the fragments" of rocks and other minerals that make up soil. This aids in the degradation of an ecosystem. The biodiversity of ecosystems is essentially wiped out because of erosion. Deforestation is the main cause for erosion. It reduces the amount of rooted plants significantly leaving the soil bare and unsupported. When water flows over or through the soil, little by little the richness and amount of soil is reduced, because it is being carried away. However, there were some errors while executing this lab. The exact amount of soil placed in each bottle was unaccounted for. The grass was planted with half organic, half regular potting soil. One soil could have had a higher water holding capacity. This means that the water released by the grass bottle maybe skewed. The other two bottles held regular potting soil.
Citations:
"Erosion and Weathering." National Geographic. N.p., n.d. Web. 16 Nov. 2013.
<http://science.nationalgeographic.com/science/earth/the-dynamic-earth/weathering-erosion-article/>.
- The water collected from the grass bottle was very transparent. You could clearly see through the water. There was sediment present both floating at the top and the more dense material at the bottom. The next bottle, ground cover, was more opaque. The amount of small particles found in the water was apparent because of this. As present in the grass water, sediment was present at both water level and at the bottom. The final bottle tested was the loose soil. The water that drained from the bottle brought with it a lot of soil. To test visibility of the water, I placed my finger in and it could only be seen from about 1 cm away from the beaker. Had I moved my finger any further it would not have been visible.
- Planting grass seed would be the most logical and environmentally friendly task to do after deforestation. The roots of the grass hold the soil together better than leaf litter or leaving it bare. As seen in the data above only 51% of the 500 mL of water poured on the grass was returned. This is better than the 65% and 84% water returns produced by the ground cover and bare soil respectfully. This means better porosity in the soil and less permeability. The soil return of the grass was also significantly less than that of the other two.
- A grass setting would allow for better water filtration because the hydrologic cycle is added by vegetation. The plants use the water to help make food and go through the process of transpiration (evaporation from plants). This leaves behind all the pollutants found in water. Grass will also prevent those pollutants from getting into the drinking water, at least to a point that isn't noticeable or threatening.
- This lab could be done on a larger scale by using the side of a hill. The hill could be segmented into three equal parts, one with grass, gravel/leaf litter, and just bare soil. A sprinkler could be run twice a week on Monday and Thursday from the top of the hill to simulate rain. This time gap will allow the soil to recover. When rain is present during the month of testing factor that into the weekly schedule. After a month, an assessment could be made to determine which segment has held up better.
General Conclusion:
This lab has allowed us to understand how erosion works. It now makes sense that soil held together by some rooted plant is the best way to prevent erosion. This experiment proved my hypothesis to be true. National Geographic says that "Erosion transports the fragments" of rocks and other minerals that make up soil. This aids in the degradation of an ecosystem. The biodiversity of ecosystems is essentially wiped out because of erosion. Deforestation is the main cause for erosion. It reduces the amount of rooted plants significantly leaving the soil bare and unsupported. When water flows over or through the soil, little by little the richness and amount of soil is reduced, because it is being carried away. However, there were some errors while executing this lab. The exact amount of soil placed in each bottle was unaccounted for. The grass was planted with half organic, half regular potting soil. One soil could have had a higher water holding capacity. This means that the water released by the grass bottle maybe skewed. The other two bottles held regular potting soil.
Citations:
"Erosion and Weathering." National Geographic. N.p., n.d. Web. 16 Nov. 2013.
<http://science.nationalgeographic.com/science/earth/the-dynamic-earth/weathering-erosion-article/>.