Looking for some inspiration for the second part of the 2017 Hermitage Schools Plant Science Competition? Remember, you have until the 23rd of June (end of term 2) to submit your reports. The competition instructions suggest allowing at least 6 weeks if you are growing plants. A hint, if you are running out of time, is to write up as much of your report as you can while the plants are still growing. Of course, you won’t be able to write up the results, but you could do at least the introduction and method, and update them later if required.
Here are a few of my favourite experiment to do with soils:
- How does the soil microbiota affect the growth of plants? I would like to see what the effect of sterilising the soil plants are grown in, compared to a sample of normal soil. One way to sterilise the soil would be to heat it in a tray in the oven at over 70°C for about an hour, but would that evaporate or burn important organic compounds in the soil as well?
- What are the effects of plants on soil erosion? Presumably, they reduce erosion, but by how much? This Science Buddies experiment gives a basic outline of what you would do, but there are many ways you could make it more realistic. Does grass really hold creek banks together?
- What factors affect the activity of nitrifying bacteria in soils (either free-living or in a symbiotic relationship with plants)? This idea is from the Biology EEI Ideas page, and factors that are said to affect the bacteria are temperature, the amount of oxygen (e.g. waterlogging), moisture, pH, salinity and light.
- How do soil conditions affect the growth of plants? This could include salinity levels, moisture levels and amounts of individual minerals (e.g. nitrogen, phosphorous, potassium and other macro- or micro-nutrients).
The ideas given in the competition instructions (with my thoughts added) include:
- How do different rates of fertiliser (normal, half, double strength) affect plant growth? Presumably, there is an optimum point where adding more fertiliser has no further benefit to the plant, and then growth declines with higher concentrations of fertiliser.
- How do different types of fertiliser (organic vs inorganic) affect plant growth?
- How does soil pH affect plant growth? Kits to measure soil pH are available from Bunnings for $16.70, and can perform up to 100 tests. How would you vary the soil pH? You could collect soil from different areas and measure their pH, but there would be other factors that would also be different, such as nutrient levels.
- Do plants grow better in hydroponics or in soil? You would have to figure out how to control the amount of nutrients, to ensure that the plants in the hydroponics aren’t getting more nutrients than the ones in the soil.
- Microorganisms that live in soil… How could you make this into an experiment? Does the number of microorganisms correlate to how well plants grow in the soil? Is that because the microorganisms make the plant grow better, or is it just because the microorganisms prefer to live in nutrient rich soil?
- Compost experiments – what to study? You decide!
Hopefully, these ideas get you thinking, but there are plenty of other sites out there with great ideas. Science Buddies has some great ideas, and the experiments are usually fairly simple to conduct. By far, the best source of experiments I have come across are Richard Walding’s pages for senior EEI ideas – Biology, Chemistry and Physics. They are aimed at grade 11 and 12, so may be a little advanced, but his ideas are amazing!
Quite often, the best experiment ideas are ones that you think of yourself. So what do you want to know about your soils?