My son is working on a school project, He wants to measure microbiological interaction with soil and plant.

In his protocol, he has to measure the amperage of the soil. I would like to help him with some automation and Arduino.

But I can't find a module that does this work for him.

Have you got some resources or maybe a small and easy PCB to achieve this?

Firsts measurements tend to reveal that microbiological product small ampere, near the micro/nano ampere.

Edit : I think I don't explain correctly what we are trying to achieve : The plant rejects sugar through its roots, then the bacteria eat the sugars and these bacteria release electrons in the medium, and it is this phenomenon that we want to measure. It is the bacteria that produce the electrons because a whole test protocol has been put in place to ensure the phenomenon. So we want to monitor this electron production and then make some and correlations analyze to see if it's benefit to the plant or not.

  • 3
    What exactly do you mean with "amperage"? If you want to measure current, then please explain where exactly that current is flowing. Or do you want to measure conductivity of the soil? – chrisl Mar 5 at 14:40
  • you need to get something like eevblog.com/projects/ucurrent, which can amplify nanoamps into something a normal DMM can read. – dandavis Mar 5 at 20:15
  • I've seen this product, ucurrent from my search, but I would like to know if with a arduino and internal OP Amp we can achieve something like this. As it is shown here, but with microampere order circuitdigest.com/microcontroller-projects/arduino-ammeter – Leze Mar 8 at 19:46
  • I adding more information about the experience – Leze Mar 8 at 19:56
  • The simplest way to measure a current is to measure the voltage across a shunt. If the current is to small and/or the output impedance of the soil-as-current-source too high, you may need an amplifying state. Can you get a sensible voltage reading with a DMM across a high-value resistor? – Edgar Bonet Mar 9 at 10:25

I think he wants to measure the resistance of the soil. I saw many projects (I was a science fair judge) that did it with an ohm meter or variation thereof. They would have several samples of soil and add nutrients to it, generally with water. Salt was the best conductor. Similar tests were performed using Ph as the measurement. An Ohm meter passes a current through the DUT (Device Under Test) and measures the voltage drop to determine resistance, maybe that is where amperage came from. I am guessing this is maybe about a seventh grade project. More information always helps.

  • i'm thinking it's more along the line of a potato clock, which can also use a potted plant. – dandavis Mar 5 at 20:13
  • Try this link: upsbatterycenter.com/blog/make-potato-battery I googled "potato battery experiment". See if this is closer to what you want? – Gil Mar 7 at 22:15
  • He doesn't want to measure the resistance of the soil, in his project some microbiological bacteria will consume material in soil and then produce a current. He had already get proof of this by taking measures with an ammeter and observe the production of microampere from this bacteria. – Leze Mar 8 at 19:44
  • It's not like the potato, as potato battery produces electricity with oxydoreduce from the electrode. Here are bacteria that produce electrons by consuming sugar that plant's roots reject. – Leze Mar 10 at 8:36
  • Current is a flow of electrical charge carriers, usually electrons or electron-deficient atoms. The common symbol for current is the uppercase letter I. For the electrical charge to flow there needs to be a potential difference, The common symbol is V. This leaves resistance which restricts the flow or the letter R. These are defined in Ohm's law. This link has a good explanation. leonics.com/support/article2_2j/articles2_2j_en.php – Gil Mar 11 at 16:43

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