Hi everybody
Can anybody advise please, I wish to measure nitrogen,potassium and phostrogen ideally in a leaf sample although soil would suffice. Do the above elements vary conductivity at different frequencies, I have seen a conductivity probe using stainless steel prongs that output npk data via serial and wondered what their working principle was and if I could make similar when sampling the brix of a leaf. As always thank you for any input, best regards

 

Can anybody advise please, I wish to measure nitrogen,potassium and phostrogen ideally in a leaf sample although soil would suffice. Do the above elements vary conductivity at different frequencies, I have seen a conductivity probe using stainless steel prongs that output npk data via serial and wondered what their working principle was and if I could make similar when sampling the brix of a leaf. As always thank you for any input, best regards

You can obtain very accurate results by measuring sample excitation at frequencies in range 480 THz - 750 THz.
ADDED:
Multi-element quantitative analysis of soils by laser induced breakdown spectroscopy (LIBS) coupled with univariate and multivariate regression methods

 

You can obtain very accurate results by measuring sample excitation at frequencies in range 480 THz - 750 THz.

Visible light. What a concept!

 

Perhaps he we referring to colorimetry and spectroscopy, both of which typically reference the wavelength, not the frequency. Most soli fertility analysis methods use spectroscopy to quantitate ppm levels of NPK.

https://agsci.psu.edu/aasl/soil-testing/methods