MJ Preiner, NC Koshnick, JS White, JP Strachan – US Patent 20,160,146,728, 2016
The nitrate-nitrogen concentration in soil is estimated based on the nitrate-nitrogen 200 nm absorption peak. In one embodiment, a device measures the attenuation spectrum of a soil-extractant mixture over a wavelength range that includes wavelengths in the vicinity of the 200 nm absorption peak (the spectral operating range) and then determines the nitrate-nitrogen concentration based on the attenuation spectrum
… The optical fibers are standard silica fibers. The detector is a Stellarnet EPP2000C spectrometer,
with a wavelength range of 190-850 nm.
