# Measure water in soil

#### Cytram

Sep 11, 2012
3
Hey!
I have an electronics project in school where I need to measure the water value in soil where a plant lives.
How can this be done?

#### CocaCola

Apr 7, 2012
3,635
Lots of ways, I know of a dead simple way to do it, but giving you the answer to your homework isn't what we do, we will help guide you though... Since it's a school project I suspect you have some guidance or background, and this isn't just a random project out of the blue... Tell us your ideas on what you think might be a good approach and we will likely be able to steer you towards the better ones... Tell us what tools you would think would do the job... Basically make an attempt and we will help, but most won't just hand you the answer on a silver platter...

Jan 5, 2010
7,682

Bob

#### CDRIVE

##### Hauling 10' pipe on a Trek Shift3
May 8, 2012
4,960
Here's a clue of how to proceed.. When you electrically measure soil moisture your actually measuring resistance. In other words a common Ohmmeter can be used. If I were doing this I'd use a cheap analog or digital panel meter.

#### Cytram

Sep 11, 2012
3
I have a school project, where I'm gonna build a growth house, where we are gonna measure temperature, humidity and measure have much water there is in the soil.

#### CDRIVE

##### Hauling 10' pipe on a Trek Shift3
May 8, 2012
4,960
I have a school project, where I'm gonna build a growth house, where we are gonna measure temperature, humidity and measure have much water there is in the soil.

This is just a repeat of your first post.

#### Cytram

Sep 11, 2012
3
i'm not the best at English.
i i belive i can some how measure the power through soil, some have make it to a capasiter?
In the end i should be connectet to a A/D .

#### (*steve*)

##### ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd
Moderator
Jan 21, 2010
25,510
Here is an authoritative link describing a number of ways to do it.

#### wingnut

Aug 9, 2012
255
Here was a circuit which detected dark and switched on D1 (LED).
D2 was an infrared photoresistor which in the presence of light, switched off the LED.

You could adapt this by removing D2 and in its place have two probes (wires) going into the soil. When the soil is wet, a small current flows between the probes and the LED switches off. When the soil is dry, it does not conduct and the LED comes on, telling you to water your plants.

#### Attachments

• DarkDetector.jpg
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#### CDRIVE

##### Hauling 10' pipe on a Trek Shift3
May 8, 2012
4,960
This is your crusade... "Stop the culling of Cape Town's baboons! "

This why I usually stay clear of this section of the forum. The policy is to not do a student's homework for them, yet it happens far too often. Todays students have a powerful resource that was not available to my generation, it's called Google. As I see it, our job is to nudge the student into resolving the homework on their own. They also have electronic calculators, Spice, on-line calculators and on and on....

We will never break free of society's accepted mediocrity by doing a students homework for them. If his instructor has given this assignment then he must feel that the class is, or should be, at a level of understanding to do the homework.

If the OP posts his own circuit we can correct errors by coaxing him into troubleshooting the error without actually fixing it for him. He will gain far more understanding and confidence than he will by telling him that the value of Rx should be 1K.

It is my opinion that with todays level of Information Technology there should be no excuse for a sub par student. If, with all this available to today's students, they find they still can't keep up with the class, then it's time to consider another course of study.

If I've offended anyone I'm sorry. Sometimes telling the truth hurts.

Chris

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#### wingnut

Aug 9, 2012
255
Chris - I appreciate what you say.

Why I posted the circuit was because the description of the project did not sound like they were going to get marks for devising their own circuit, but for building something which does the job. I would be surprised if they are electronics students or if this is an electronics project per se. This is a school project to build a slightly automated greenhouse.

I felt it was going to be hard enough for them to buy the parts and get it to work as it is. And like you posted, one could stick multimeter probes in the ground- but one cannot leave it there permanently.

I also doubt the aim of their project was to test their googling skills.

I used to teach technology and was glad when parents would buy a robotics kit for their kids project and help the kid assemble it. There were some absolutely fantastic projects done with a lot of input from adults.

I really did not think that giving a student a circuit was excessive help, unless these are electronics students - which I seriously doubt. But I really don't want to offend you or others here either.

#### CocaCola

Apr 7, 2012
3,635
This is your crusade... "Stop the culling of Cape Town's baboons! "

This why I usually stay clear of this section of the forum. The policy is to not do a student's homework for them, yet it happens far too often. Todays students have a powerful resource that was not available to my generation, it's called Google. As I see it, our job is to nudge the student into resolving the homework on their own. They also have electronic calculators, Spice, on-line calculators and on and on....

We will never break free of society's accepted mediocrity by doing a students homework for them. If his instructor has given this assignment then he must feel that the class is, or should be, at a level of understanding to do the homework.

If the OP posts his own circuit we can correct errors by coaxing him into troubleshooting the error without actually fixing it for him. He will gain far more understanding and confidence than he will by telling him that the value of Rx should be 1K.

It is my opinion that with todays level of Information Technology there should be no excuse for a sub par student. If, with all this available to today's students, they find they still can't keep up with the class, then it's time to consider another course of study.

If I've offended anyone I'm sorry. Sometimes telling the truth hurts.

Chris

I fully agree, today's students have it WAY too easy already... A 24/7 repository of information the size the World has never known at your finger tips... If I had half that when in school there would have been zero excuse to not be a perfect straight A student...

And the sad tiny violin song they play all the time that the teacher just tossed this project upon them with no foundation or knowledge of how to solve it is a joke... The truth is they probably took the lazy route for the earlier projects getting the answer handed to them for those projects so that they never learned anything they were supposed to... Now when they have to apply what they were supposed to have learned (but instead were given) they fall flat on their face crying foul...

I'm all for 'helping' and 'guiding' but handing lazy people the answer on a silver platter is just contributing to their laziness that will only compound the more it's fed...

#### CDRIVE

##### Hauling 10' pipe on a Trek Shift3
May 8, 2012
4,960
I also doubt the aim of their project was to test their googling skills.

It's impossible for any of us to know everything. That said, a substantial part of any science is having the ability to do research. With Internet availability a student can be anywhere on this earth and never have to walk to the library. If an old fart like me can do it then I fully expect a young fresh mind to be able to outshine me any day of the week.

The media keeps telling us that this generation is far smarter and technology savvy then any generation before them. Personally, I don't think the media knows their ass from a hole in the ground! After all they chose a coaster major themselves.

Chris

#### CocaCola

Apr 7, 2012
3,635
unless these are electronics students - which I seriously doubt.

Why do you seriously doubt? It's clearly an electronics exercise thus it's hardly a bold leap to assume it's for an 'electronics' or at minimal 'tech' class... Like any school project it's an exercise in education and learning for the student, not a find someone else to do your homework for you exercise... If it's just find a solution go get one of these no knowledge gained, no education learned and no brain work at all, on a silver platter solution...

I also doubt the aim of their project was to test their googling skills.
Google is a BIG part of today's education process... Not too long ago the teachers were quite up front that part of many assignments was to force the student to hit up the library and learn how to use the card catalog and do there own research for the answers, why do you suspect that learning todays research skills are no longer part of the assignment?

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#### CDRIVE

##### Hauling 10' pipe on a Trek Shift3
May 8, 2012
4,960
I fully agree,

CC, life is full of surprises but this isn't one of them.

Chris

#### wingnut

Aug 9, 2012
255
In our country, I can tell you with certainty that they do not teach electronics at school. Electricity and Ohm's law and adding resistors, etc. but no semiconductors - either in technology or science - both of which I teach. This lack is causing dumbing down - and from next year they have even removed capacitors from the science syllabus - and removed electric circuits from Matric - because, I suspect, Gr12 students (and teachers) struggled too much with these.

Doing internet research is important in many subjects, but if students are not taught electronics, they have zero ability to find or recognise an electric circuit which is easy to make and work.

Some specialised trade schools teach electronics - but I would be highly surprised if the OP goes to one of these.

This sounds to me like a typical project where the teacher says "design and make anything" and they get marked for going through the steps of the process (rough drawing, planning your time, neat drawing, making a model, testing etc) and most kids make a volcano - and these students have chosen a bit of electronics - and I feel one should make it easier for the modern student to put together a circuit - it is hard enough as it is - because even I struggle.

#### CocaCola

Apr 7, 2012
3,635
I can state that none of that is in anyway universal across the globe.. There are plenty of secondary education schools, colleges, tech schools, adult education and universities teaching electronics classes in many, many countries... I even had basic electronics back in high school general shop class... I didn't have any advanced classes at the school but there was 1/2 day off campus 'tech' school options that I could have taken my junior and senior years if I would have been interested back then... But it was a different electronics landscape, and I was much more interested in the emerging home PC and programming software at the time... There are many high school programs in my area now that have electronics classes, that include basic analog and even digital electronics based on small micro developer boards like the Ardunio and even the time traveled Basic Stamp...

#### CDRIVE

##### Hauling 10' pipe on a Trek Shift3
May 8, 2012
4,960
Wingnut, you've presented a persuasive argument. Perhaps he'll be honest enough to tell us if this is high school, vocational, or other. Yes, I totally agree that I wouldn't expect semiconductor theory to be taught in high school. Hell, we're so dumbed down in the US that most schools have ceased teaching script! College in the US has become meaningless. I love beer but it shouldn't be considered a credited course of study. We have affirmative action teachers that speak like they're "gangstas in da hood". It makes my ears bleed!

Chris

#### CDRIVE

##### Hauling 10' pipe on a Trek Shift3
May 8, 2012
4,960
There are many high school programs in my area now that have electronics classes, that include basic analog and even digital electronics based on small micro developer boards like the Ardunio and even the time traveled Basic Stamp...

Does this include Chicago? I wouldn't want one of those union bloodsuckers near my grandchildren.

Chris

#### CocaCola

Apr 7, 2012
3,635
Does this include Chicago?

Surprisingly yes, in some of the elite upper class Chicago neighborhoods, the schooling is top notch, but no so for the vast majority of the city... Chicago like any city goes from gutter poor to wealthy in one block and the schools follow the same pattern... And to be realistic if the kids won't and don't want an education the teachers are between a rock and a hard place...

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