Detection of nitrogen and phosphorus nutrient status in winter wheat using spectral radiance

Abstract Nitrogen (N) and phosphorus (P) are major limiting nutrient elements for crop production and continued interest lies in improving their use efficiency. Spectral radiance measurements were evaluated to identify optimum wavelengths for dual detection of N and P status in winter wheat (Triticum aestivum L.). A factorial treatment arrangement of N and P (0, 56, 112, and 168 kg N ha‐1 and 0, 14.5, and 29 kg P ha‐1) was used to further study N and P uptake and associated spectral properties at Perkins and Tipton, Oklahoma. A wide range of spectral radiance measurements (345–1, 145 nm) were obtained from each plot using a PSD 1000 Ocean Optics fiber optic spectrometer. At each reading date, 78 bands and 44 combination indices were generated to test for correlation with forage biomass and N and P uptake. Additional spectral radiance readings were collected using an integrated sensor which has photodiode detectors and interference filters for red and NIR. For this study, simple numerator/denominator indic...