Are there nitrate/nitrite sensors for soil?

Hi GOSH Community,
I am an absolute layman in Biology and Biochemistry, but was looking for some “real-time” nitrate/nitrite sensors some colleagues of me and I could use in soil (!) via microcontroller. It seems to be a hot topic in agriculture for quiet some time now, but the devices I’ve found are either enormous and/or really expensive. Are there any buying options or Open Hardware attempts for something like that so far?

Thanksalot for any answers!


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Hi Paul,

I’ve been involved with an OSHW nitrate measuring system for soil. The web page is in German, but the github repro is English as well (at least most of it):

CitizenSensor is NOT a real time system. We have evaluated the possibility to build one, but found that it is very hard to do, at least if you want results comparable with official measurement methods. These involve taking several samples, mixing them, mechanically break them down, sieving, filtering, and preparing an aqueous solution.

We have come up with a simplified DIY solution for this procedure:

Not sure if this helps you, but I’m happy to answer more questions about our project if there is interest.

Best regards,


Hi all
Sometime ago we played with Hach NitraVer5 and a colorimeter adapted from the one of IO Rodeo. We did it with soil too followig Hach manual making an aqueous solution and filtering. This kit is not so friendly because uses Cadmium reduction method… but there is an enzimatic reaction and also just another open colorimeter @jpearce

I really like it! Did you build the probe/electrode or is a commercial one?

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We use a commercial nitrate electrode.
The CitizenSensor project includes a Raspberry Pi HAT doing the measurements and a step-by-step wizard on the Raspberry Pi for preparing the aqueous solution. It uses an integrated load cell for weighing the solution and a small magnetic stirrer to enable this.

Our project partner Fraunhofer EMFT started developing their own electrode, but it was in an too early stage to be used in the CitizenSensor project.

Best regards,

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Hello Paul,
Which type of sensors have you look at? Did you investigate electrochemical sensors? They are rather compact.

Nice to see all those great documentations! thx @drayde
We also looked into this some time ago, minimal docu on hackteria wiki

Mostly also looked at those colorimetric tests, and convert nitrate to nitrite first, using zinc. but it wasnt so easy on the first tests, and discontinued.

A comment on that colorimetric paper, it’s “all” open source, but if you read the details, the enzymatic reagents are NOT; and seemingly quite patented and commercial. I have been commenting on this as a bit of a open-washing, when only the hardware is open in a whole measurement system, but not the system itself.

I read german, so really nice to see that description. Does this method also need the nitrite conversion first?
I would also like to learn more about the electrode sensor itself. Do i see it right, that we are expecting a prize of ca 1000 $ for a sinlge one?
How could we reprocuce your setup ourselves? i’d love to do some testing myself, here in Indonesia.

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Hello @dusjagr
I just found a review paper with various type of electrochemical sensors for nitrate: Electrochemical sensors for nitrogen species: A review - ScienceDirect
Some electrodes doesn’t look too complicate to produce.
Best regards,

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Hi @dusjagr , I don’t know too much about the electro-chemical mechanism involved, but I can get you in touch with the expert in our team if you are interested. The step from aqueous solution to the actual measurement is described here: Usage_Preparation

The commercial electrode we are using is a PASCO CI-6735, price is around 300 Euro.

The GitHub repository includes all the sources you need to build a device yourself. The electronics includes a BGA which is hard to solder, so a PCBA service should be considered. Maybe we can help here, DM me if you are interested.

Best regards,

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With a little robotics - you could automate this open source nitrate tester we developed a few years ago -

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