I stumbled upon this new device called Teralytic. Which can measure salination, NPK values and all sorts of things.
Unfortunately it's sold out and I think when it'll be available again rather expensive. So I as a hobbymaker thought maybe I can build something like this myself? So I was wondering how do they measure these things rigth in the soil itself? The only thing that might be helpful is this but It doesn't say wheter they used prepared soil samples or just a nomral earth right from their garden or somewhere. Does anyone maybe have an Idea how they could've done it? What techniques have they used?