<p>I'm doing a project in junior year chemistry where I get to choose what I investigate as long as it covers course content. I'm interested in exploring how quantitative (ig. incremental) change in an independent variable of soil would change some dependent variable -- particularly through experimentation.</p>
<p>I was thinking of seeing how changes in soil pH affect soil fertility, with specifically focusing on phosphate content to measure soil fertility for simplicity + it's the easiest (i think) to do an experiment over. However I'm not sure if there's correlation between these two variables (which wouldn't look good).</p>
<p>Any recommendations for independent/dependent variables with correlation + a useful for real-world application of soil chemistry to look into, where a high school level experiment could produce useful observations, would be super appreciated. That's if you think my original phosphate x pH idea wouldn't make sense.</p>

CC BY-SA 4.0
2020-12-16T20:15:12.297Z
I understood : fixed variable and adjusted variable... I didn't understand the dependent/independent terminology. Do you mean that you would want to use a soil with the same Phosphate content, and vary the pH and see how fast cress grows? it's difficult to make a difference between phosphate and other soil minerals if they are all necessarily there.
bandybabboon
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2020-12-16T21:41:01.147Z
If you vary phosphate , you are varying fertility , not just pH.
blacksmith37
CC BY-SA 4.0
2020-12-17T06:42:46.640Z
A few thoughts that might clear up: first off, you're talking high school chemistry, yes?  Junior could theoretically be university.  And you're talking about first year intro chem, not like AP or anything else more advanced?  Just helps to get an idea of what a teacher may want.
JeopardyTempest
CC BY-SA 4.0
2020-12-17T06:47:54.887Z
Now I'd think usually in a high school science experiment, you're not expected to KNOW there's a connection between two variables, but to see if there is one.  So I don't think it'd particularly look bad if you found no correlation between two variables, high school experiments should find that quite often (that's science... it may not be the most interesting result, but it still says something... then you try to explain why there's no connection).
JeopardyTempest
CC BY-SA 4.0
2020-12-17T07:23:17.813Z
Certainly if you go in with 2 variables and a fair conjecture of why you'd think they may be related (so you're not just picking 2 absolutely wild variables for no good reason), that's reasonable work to me... and I've definitely judged science fair projects that weren't so rigorous, just choosing a wider group of random variables, looking for connection without much rationale, and still seemed decent too. Certainly eye-opening connections are more exciting, and often win fairs, but science is science, and I'd hope the teacher grades a null result just as high if it's presented\reasoned well.
JeopardyTempest
CC BY-SA 4.0
2020-12-17T07:49:58.773Z
https://www.soils.org/news/science-news/soil-phosphorus-availability-and-lime-more-just-ph does offer some hope. I can see where a teacher might consider it impossible to make pH the independent variable, as either actively altering it, or choosing soil\rock with different pH, must require a different chemical composition of the soil... which may directly mean P levels are different (so hard to keep control\weigh dependence? [it'd come down to which rock and\or acid\base you chase rather than a more universal correlation?]) But someone more versed in soil science\geology may be better input.
JeopardyTempest
CC BY-SA 4.0
2020-12-17T07:51:28.837Z
[Chat](https://chat.stackexchange.com/?tab=site&host=earthscience.stackexchange.com) may be a place you can get more discussion and refine your project idea and this question before anyone would have a great answer
JeopardyTempest
CC BY-SA 4.0
2020-12-17T10:27:23.647Z
thanks for all the help! just to clarify: i'm in junior year chemistry in high school. technically my course is IB SL chemistry but i'm not sure if that's a commonly known course everywhere -- it's basically the same difficulty as AP chemistry.
Joshua
CC BY-SA 4.0
2020-12-17T10:28:29.623Z
i'm thinking of not going with soil anymore and instead looking at how changes in water pH affect water hardness. i found a good experiment procedure to follow to measure phosphate concentration in soil, but it used sulfuric acid. i'm basically not allowed to use any concentrated and dangerous acids in my experimentation, and it seemed like to measure nutrients in soil that would be a necessity (if i didn't want to go with a super complex alternative or buy a test kit)
Joshua
<soil><soil-science>
Looking for variables to compare against pH of soil
Joshua
# Looking for variables to compare against pH of soil

(Asked by: username_0 on 2020-12-16)

I'm doing a project in junior year chemistry where I get to choose what I investigate as long as it covers course content. I'm interested in exploring how quantitative (ig. incremental) change in an independent variable of soil would change some dependent variable -- particularly through experimentation.

I was thinking of seeing how changes in soil pH affect soil fertility, with specifically focusing on phosphate content to measure soil fertility for simplicity + it's the easiest (i think) to do an experiment over. However I'm not sure if there's correlation between these two variables (which wouldn't look good).

Any recommendations for independent/dependent variables with correlation + a useful for real-world application of soil chemistry to look into, where a high school level experiment could produce useful observations, would be super appreciated. That's if you think my original phosphate x pH idea wouldn't make sense.

**Tags:** soil, soil-science

> **Comments:**
> **username_1**: I understood : fixed variable and adjusted variable... I didn't understand the dependent/independent terminology. Do you mean that you would want to use a soil with the same Phosphate content, and vary the pH and see how fast cress grows? it's difficult to make a difference between phosphate and other soil minerals if they are all necessarily there.  
> **username_2**: If you vary phosphate , you are varying fertility , not just pH.  
> **username_3**: A few thoughts that might clear up: first off, you're talking high school chemistry, yes?  Junior could theoretically be university.  And you're talking about first year intro chem, not like AP or anything else more advanced?  Just helps to get an idea of what a teacher may want.  
> **username_3**: Now I'd think usually in a high school science experiment, you're not expected to KNOW there's a connection between two variables, but to see if there is one.  So I don't think it'd particularly look bad if you found no correlation between two variables, high school experiments should find that quite often (that's science... it may not be the most interesting result, but it still says something... then you try to explain why there's no connection).  
> **username_3**: Certainly if you go in with 2 variables and a fair conjecture of why you'd think they may be related (so you're not just picking 2 absolutely wild variables for no good reason), that's reasonable work to me... and I've definitely judged science fair projects that weren't so rigorous, just choosing a wider group of random variables, looking for connection without much rationale, and still seemed decent too. Certainly eye-opening connections are more exciting, and often win fairs, but science is science, and I'd hope the teacher grades a null result just as high if it's presented\reasoned well.  
> **username_3**: https://www.soils.org/news/science-news/soil-phosphorus-availability-and-lime-more-just-ph does offer some hope. I can see where a teacher might consider it impossible to make pH the independent variable, as either actively altering it, or choosing soil\rock with different pH, must require a different chemical composition of the soil... which may directly mean P levels are different (so hard to keep control\weigh dependence? [it'd come down to which rock and\or acid\base you chase rather than a more universal correlation?]) But someone more versed in soil science\geology may be better input.  
> **username_3**: [Chat](https://chat.stackexchange.com/?tab=site&host=earthscience.stackexchange.com) may be a place you can get more discussion and refine your project idea and this question before anyone would have a great answer  
> **username_0**: thanks for all the help! just to clarify: i'm in junior year chemistry in high school. technically my course is IB SL chemistry but i'm not sure if that's a commonly known course everywhere -- it's basically the same difficulty as AP chemistry.  
> **username_0**: i'm thinking of not going with soil anymore and instead looking at how changes in water pH affect water hardness. i found a good experiment procedure to follow to measure phosphate concentration in soil, but it used sulfuric acid. i'm basically not allowed to use any concentrated and dangerous acids in my experimentation, and it seemed like to measure nutrients in soil that would be a necessity (if i didn't want to go with a super complex alternative or buy a test kit)  

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## 0 answers

