Question: How are we going to get rid of our thistles in our area? Quadrant Research: North West corner, lots of thistles, broken branches, a lot of flax bushes on the other side of the fence, one big tree, three worms at the start of the project and grass grubs. Soil Type: crumbly on top and moist down the bottom. We Found in our quadrant: Three worms, a grass grub, and lots of thistles, broken branches. FAIR TEST For our fair test we put a cable drum on the thistles as well as boiling water, weed mat and grass clippings to see if it will kill the thistle. Process: First we put all the materials on one thistle each and waited 6 days then we took the materials off. Results: The cable drum killed the thistle. We also found 5 worms and 2 grass grubs underneath it.Limehills Scientists: Josh, Kacee, Matson, Dylan, Sally and Billy
Hypothesis: We think that if we put wood on the thistles it will kill them by blocking out the sun.
The hot water burnt it the moment it touched the thistle but at the bottom of the thistles it was green.Expert Feedback from Sue Barker of DOC
What interesting ideas to get rid of the thistles. From what I understand you put each of the changes (cable drum, hot water, clippings and weed mat) on a different thistle and after 6 days lifted them to see the results?
Can you also say what the results of the clippings and weed mat were? I think your ideas are great – I just need a bit more explanation to understand your scientific methods.
It seems from your results that light is essential for plants to survive.
Feedback from Chris Green, Technical Support Officer, Biodiversity (Invertebrates and Biosecurity) at DOC.
A very good experiment and I agree with Sue's feedback.
It is really a good idea to record the quantities of your materials, how much boiling water, how big was your container of grass clippings and how big was you weed mat? Was the amount of grass clippings enough to completely cover the thistle so that all the light was excluded? Sue might be right that light is essential for a thistle to grow but does it need space as well. Do you think that the weight of the cable drum was different from the other materials and that this may have had an influence? Were the results of the weed mat and grass clippings different from that of the cable drum? If it was just light that the thistles were depending on then the one under the weed mat shouldn't have looked very healthy after the experiment. What did it look like?
Did you record any worms or grass grubs under the grass clippings or weed mat after 6 days? At the start of the study how big an area did you search in order to find the three worms and the grass grub? Did you search and find them under just one thistle or under lots of thistles, if so how many? It would be really good to know so you can compare the 5 worms and 2 grass grubs found under one thistle at the end with what would have been under one thistle at the start. This means you would be comparing the results from similar sized areas which is always a good idea.
Also, you need to answer the question you set yourselves - how are you going to get rid of the thistles? If only the cable drum killed the thistle then do you need lots of cable drums? Or could you use fewer drums but move them how often?
Good work but a few more details will make all the difference.