Although the pH sensor doesn't necessarily tell you the lime requirements, it does identify field areas needing lime. We use it to show the highs and lows on a map. Then we take manual soil tests and use those as a calibration for the map, which helps us to perform variable-rate applications.

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None of them are designed for the kind of impact that occurs when you insert an electrode into a core of soil. However, for pH they work fairly well. For nitrate, potassium and some other ions, the reliability of recently developed on-the-go measurements remains in question.

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