I tested my garden soil (NPK for guidance in applying fertilizers) but now I'm questioning my results.

I collected the soil as per the instructions and left it to dry in a bucket. Once dry, I left it for several months in a garage, exposed to open air.

Would this change the amount of phosphorus or nitrogen detected by a soil test? These two components came back as depleted.

  • If you followed some technical instructions, then that's how it is. Care to share the origin and content of the instructions ? Feb 27, 2023 at 1:48
  • The instructions did not specify if a sample needed to be processed within a certain window
    – nuggethead
    Feb 27, 2023 at 2:46

1 Answer 1


Unlikely, unless you had just applied a volatile form of nitrogen fertilizer (inclusive of tilling in legumes, evidently)

Phosphorous is essentially non-volatile, so drying in a bucket sould not remove any (it's lost by leaching, erosion, and plant uptake)

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