This might be useful as a model for any Snell students with a Science Fair Project.
LOG BOOK:
Background Observations:
During the summer Melanie began to notice bubbles forming on the soil surface when she begins watering - for about 15 seconds. She did wonder at first if someone had tipped some cleaning-up water into the garden. Then she discovered it was coming from the new school garden hose.
She also noticed that the plants in the gardens where she usually began watering where not thriving as she and the EcoWarriors had hoped. For example, the corn plants did not get very big and the zucchini plants were quite stunted too. Also some seedlings that germinated stopped growing altogether.
Ideas:
26th March
Melanie suggests to the Snell EcoWarriors that we could carry out an experiment to find out if the water is affecting the plants. They agree and begin to brainstorm how they could do this.
E.W. Ideas: Test the water. Research what is in the hose. Compare the growth of plants - some watered with hose water and some with water from tap.
Began to think about how many plants we would need - the more the better, as some plants just don't grow well for other reasons.
Hypothesis Idea:
Something in the hose water is limiting the growth of the garden plants.
Research Ideas:
What are hoses made from? What could form bubbles? Is it just aeration bubbles? Could it be a chemical from lining that dissolves in water? How could we test the water - do it ourselves or use experts? What causes the kind of stunting in plants we saw?
Category:
If this was a Science Fair Project, it could possibly fit either in the Material World category (we are interested in water or chemicals in the water) or the Living World category (testing resulting plant growth). If it was in the Living World category, it wouldn't require ethics approval, as it doesn't involve animals).
Hypothesis:
That the plants watered with the bubbly hose water will not grow as big as the plants watered with ordinary tap water.
Planning the Practical Work:
7 May
Melanie buys a bunch of lettuce seedlings to use for the experiment.
E.W.s agree that testing a large number of plants is going to give the most convincing result. We decide to use 15 plants for watering with the hose water and 15 plants that we will water with the tap water (these are the control group).
The variable that we will change is the water type. All other variables must be kept the same. We brainstorm some variables to keep the same:
Sunlight, amount of water, pot, soil, type of plant, shelter, insects and other creatures that might affect them, fertiliser, how we water them.
We also decided we would need to cover the seedlings from rain, so that we could control the watering.
Practical Work Notes (Method):
7 May (Set up of Experiment)
We potted up 30 buttercrunch lettuce seedlings of the same size, into pots of approximately the same size. (One pot for each seedling). We used the same potting mix.
We put together the greenhouse to protect them from rain.
We ran out of time, so Melanie finished the set-up and randomly assigned seedlings to two groups, then watered one group with tap water and one group with hose water, both from a watering can. Then she labelled all the hose group pots with a stick, and re-mixed the pots inside the greenhouse. (They were re-mixed just in case one side of the greenhouse had different conditions like more sunshine.)
21 May (Watering)
-> Carefully separated control pots (tap water) and experiment pots (hose water) so they could be watered differently.
->Third-filled watering can with bubbly hose water.
->Watered the experiment pots with this water as evenly as possible (note: decided too difficult to measure water exactly, though this would have been better).
-> Rinsed out watering can. Third-filled watering can with tap water.
-> Watered the control pots with this water as evenly as possible.
-> Re-mixed pots, and returned them to greenhouse.
4 June (Watering)
-> Repeated watering as 21 May.
-> Snell team eco-warriors couldn't notice any differences in plant growth between the two groups yet. But we won't know for sure until we measure at the end of the experiment.
-> We are planning on measuring weight (mass) of each lettuce plant to compare groups. We also discussed other ideas like measuring height or number of leaves and also whether we should weigh roots as well as leaves.
(Further watering, as above, was carried out).
2 July (Measuring Results)
-> We measured the mass (weight) of every lettuce plant using kitchen scales. We decided to cut the roots off first because it was difficult to wash all the soil out and that might influence our results. We cut the roots off at the same point on all lettuce plants to make it a fair test. We were also careful to weigh all plants in the same way - in same position, with all leaves inside. (Keeping variables the same in both groups).
Here are the two groups of lettuces - they look similar.
Results: Here are our results, recorded in a table and also as a graph. The measurements showed no clear difference between the size of the lettuces grown in tap water and those grown in bubbly water from the hose.
Evaluation/Improvements: There were some very poorly growing lettuces (light weight) in both groups, due to over-crowding. An improvement, if it were to be repeated, would be to space them apart more so they all had equal exposure to light.
Conclusion: We conclude that: whatever is making the hose water bubbly, it doesn't seem to affect the growth of lettuce plants.
Our hypothesis: "That the plants watered with the bubbly hose water will not grow as big as the plants watered with ordinary tap water."
was found to be incorrect.
Discussion: Even though our hypothesis was proved wrong, it was still a successful experiment and had an interesting result. We can also conclude that it is quite safe to water the garden plants with this water, as they should grow fine. It also means that for the plants that failed to thrive over the summer (corn and zucchini), there was likely some other cause for this.
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