Gas on Grass
If 1ml, 2ml or 3ml of gasoline is put onto grass, the grass will die, because the gasoline will stop the absorption of water to the grass. Once the gasoline absorbs into the soil, the gasoline will block the ability of the roots to consume water.
When you fill your lawnmower with gasoline, it is likely that you will spill some on your grass. This would be considered a land oil spill because gasoline is refined oil. In a land oil spill, the absorption of water is stoped and the only way for this to be prevented is to stop the oil from getting to the groundwater. If the oil gets into the soil, it blocks the roots and stops the plants from receiving water. The toxic chemicals in oil stop photosynthesis in a plant, a process that a plant needs to live. Brums and trenches are built when major oil spills occur on farmlands to protect the crops.
The control variable in this experiment is the three containers of grass without any gasoline on them. The independent variable is the different amounts of gasoline that are applied to the grass. The dependant variable is how well the grass with the gasoline on it grows.
Step 1: Get six 22.9cm x 16.5cm x 7.0cm tin containers.
Step 2: Add 4 ½ cups of soil per container.
Step 3: Put 1 ¼ cups of grass seed per container on top of the soil.
Step 4: Water the grass with 15ml of water 3 times per day for 2 weeks until grown.
Step 5: After 2 weeks measure the height of the grass in each container.
Step 6: Add 1ml of gasoline to container 1 of grass 2ml of gasoline to container 2 of grass and 3ml of gasoline to container 3 of grass. Containers 4,5, and 6 will have no gasoline.
Step 7: Continue to measure, record the heath and water the grass for ten days to see the effect of the gasoline.
On day 1, the height of the grass for all the containers was 7 cm tall. Two days after the gasoline was applied, containers 1,2 and 3 stayed at 7 cm tall but containers 4,5 and 6 grew 0.1 cm per container. On day 3, the effect of the gasoline started to show in containers 2 and 3 as they decreased in height by 0.1 cm and 0.6 cm. On days 4-10 containers 1,2 and 3 continued to decrease in height by approximately 0.2 cm, 0.3 cm or 0.4 cm each day.
In conclusion, a gasoline leak from a lawnmower would negatively affect the growth of grass as shown in this experiment. The grass with the gasoline in containers 2 and 3 started to look very dark green and shrivelled in the tips on day 3 (decreasing the height of the healthy grass). On day 4, the same thing happened to container 1 with only 1ml of gasoline. The condition of the grass continued to worsen and the whole stalk of the grass eventually shrivelled over the following days. The grass even started to yellow in some spots. This condition was caused by the gasoline because containers 4,5 and 6 (without gasoline) continued to grow healthy through the experiment. The impact to the grass in containers 1, 2 and 3 was therefore caused by the gasoline.
My hypothesis was partially correct. The gasoline did stop the plant from growing and eventually killed the grass. Initially, the gasoline was absorbed by the grass as evidenced by the change in colour to dark green rather than turning yellow like a dehydrated plant. Once the grass absorbed the gasoline it was unable to consume water and stopped growing. In a further application of this experiment, I would try to grow the grass in an outdoor environment because this is the normal setting for grass growth. By doing the experiment outside you would be able to determine if the weather further affects the grass with the gasoline. I was unable to do this because at the time of the experiment the climate I was in the grass would be incapable of any growth outside.
This experiment shows that even a small amount of gasoline can kill your grass. To prevent this from occurring, fill your lawnmower’s gas tank away from your lawn so the health of your grass is not damaged. In the big picture when gasoline is spilled on an ecosystem you are not only killing the plant life but are risking contaminating other surrounding parts of the environment. For example, if gasoline entered the water system it could harm animals and humans as well.
Sources Of Error
A limitation of this experiment is that it had to be done inside due to the weather at the time of the experiment. In a real situation, grass is normally grown in an outdoor environment so you might have slightly different results.
For my research about how oil spills affect grass, I used the website: Land-oil spill prevention by the API and the study: A Note on the Effects of Diesel Oil Spillage on Grass Growth by D. McGrath.
Thank you to my science teacher Mr.Downey for helping to answer my questions and my Dad, Kirby Podavin for helping me use the gasoline.