Abstract
After many weeks of growing grass in our class windowsill, we were finally able to test erosion on a smaller scale. We filled two more 2 liter bottles (in addition to our grass), with soil and different elements we felt could mock the grass. We chose marbles and left the other empty with just organic soil. Once all three of the bottles were set, we placed water in the back of where we cut the bottles to see which would 1. produce the most runoff, and 2. have the cleanest runoff. As I assumed in my hypothesis, the grass completely filtered out the water, and had the cleanest runoff. This is because of how long we let the roots grow. It made it obvious that grass is necessary to the filtration of runoff water.
Problem
How does grass effect the movement of water in an ecosystem?
Hypothesis
If we test grass, pebbles, and leaf litter to see which creates cleaner and less runoff, then the grass will filter the water better.
Parts of the Experiment
Control group- Bottle with just soil in it
Experimental group- Bottles with grass and marbles
Independent variable- Amount of water collected in the beaker and the density of it
Dependent variable- Amount of water used
Materials
3 liter bottles, cut in half, potting soil, grass seed, water, pebbles, gravel or leaf litter.
Method
Sowing the seeds
1. Place soil in an empty 2L bottle that has been cut in half (see picture above). Spread grass seed evenly throughout the soil.
2. Water grass seed every 3-4 days and allow it to sit near a source of sunlight or under a plant grow lamp.
Testing the effects
1. When the grass has grown 2-4 inches in height, you are ready to test the effects.
2. 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.
3. Line the three bottles up on top of an elevated surface. Place an empty beaker underneath the mouth of each bottle.
4. Prepare 4 graduated cylinders with 100 mL of water in each.
5. 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.
6. Record the time, amount, and color of the water discharge in the table below. Then, answer the questions.
Data
Bottle | Water Collected | Time for water to stop | Observations
With grass | 100 mL | 75 seconds | Clearest water, medium soil density
With marbles | 30mL | 34 seconds | Clear with a medium amount of soil, medium density
Only soil | 150 mL | 42 seconds | Brown, very dirty, muddy soil, heavy density
After many weeks of growing grass in our class windowsill, we were finally able to test erosion on a smaller scale. We filled two more 2 liter bottles (in addition to our grass), with soil and different elements we felt could mock the grass. We chose marbles and left the other empty with just organic soil. Once all three of the bottles were set, we placed water in the back of where we cut the bottles to see which would 1. produce the most runoff, and 2. have the cleanest runoff. As I assumed in my hypothesis, the grass completely filtered out the water, and had the cleanest runoff. This is because of how long we let the roots grow. It made it obvious that grass is necessary to the filtration of runoff water.
Problem
How does grass effect the movement of water in an ecosystem?
Hypothesis
If we test grass, pebbles, and leaf litter to see which creates cleaner and less runoff, then the grass will filter the water better.
Parts of the Experiment
Control group- Bottle with just soil in it
Experimental group- Bottles with grass and marbles
Independent variable- Amount of water collected in the beaker and the density of it
Dependent variable- Amount of water used
Materials
3 liter bottles, cut in half, potting soil, grass seed, water, pebbles, gravel or leaf litter.
Method
Sowing the seeds
1. Place soil in an empty 2L bottle that has been cut in half (see picture above). Spread grass seed evenly throughout the soil.
2. Water grass seed every 3-4 days and allow it to sit near a source of sunlight or under a plant grow lamp.
Testing the effects
1. When the grass has grown 2-4 inches in height, you are ready to test the effects.
2. 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.
3. Line the three bottles up on top of an elevated surface. Place an empty beaker underneath the mouth of each bottle.
4. Prepare 4 graduated cylinders with 100 mL of water in each.
5. 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.
6. Record the time, amount, and color of the water discharge in the table below. Then, answer the questions.
Data
Bottle | Water Collected | Time for water to stop | Observations
With grass | 100 mL | 75 seconds | Clearest water, medium soil density
With marbles | 30mL | 34 seconds | Clear with a medium amount of soil, medium density
Only soil | 150 mL | 42 seconds | Brown, very dirty, muddy soil, heavy density
Specific Questions
1. Describe the difference in the water collected from each of the 3 bottles.
The bottle that had only soil, turned out to be very muddy. This is because there was nothing to filter or stop the water. The bottle with the marbles was fairly dirty, the marbles helped a little bit for all the water that flowed on the surface, but not in the soil. The bottle with the grass filtered the water completely, and the only soil that went into the beaker was from the surface runoff. The roots and the grass helped filter out the water from getting muddy.
2. Using your data to support your answer, after deforestation, what would be most effective: planting grass seed, leaving rotting material behind, or leaving bare soil? Support your answer.
The most effective planting method after deforestation would be to plant grass seed. The grass seed would be able to slow down the runoff the best, just like our grass bottle in the lab did. This would also prepare the soil again for more trees to be planted.
3. Which setting would allow the greatest chance of water filtration (for cleaning pollutants, etc)? Explain your answer.
A setting with deeply rooted grass, all of the roots slow down the water and allow for the water to get through and no soil to follow. Thus resulting in clean water.
4. Describe how this lab could be done on a larger scale to test the effects over a longer period of time. Give a complete description.
This lab could be done on a larger scale in three different areas that had similar features. They would have to be on the bank of a river. In one area you could plant grass seeds, one area you could put leaf litter, and then leave the third area alone. Allow the grass to grow, and then test how much runoff gets into the river in each of the blocked off areas after rainfall or imitated rainfall.
Conclusion
My hypothesis for this lab was correct. It seems like common sense for it to be necessary for an environment to be cleared sustainably and to always have some type of plants roots in the ground (trees, grass, etc.) to help clear runoff. Even in such a small scale patch of grass, the water was so clean and filtered. The results of the soil that had no covering on it was gross, the water was so dirty and muddy. My citation article is very recent and shows the first ever photographs of where deforestation is occurring on a world map. This is extremely shocking because its gross to think of how when all the vegetation is cleared from all these parts of the world, how dirty the runoff is going to be. This is why different tree cutting methods are so important.