Utilization of Spectral Imaging to Detect N and K Sufficiency in Cotton
Apr 25, 2019
Nitrogen and K as well as other plant nutrients influence the spectral properties of individual crop leaves and plant canopies. Technology is currently available that can measure reflectance at spectral resolutions of less than 2 nm. Thus, the identification of specific changes in spectral reflectance relative to plant nutrient concentration may be possible. Field studies with variations in soil K availability and N fertilization were used to study spectral reflectance properties of individual leaves and plant canopies influenced by plant nutrition. Leaf samples at different stages of plant development were used to determine the N and K status and their relationship to spectral images and reflectance measurements. Aerial images were taken at 1067 m. with four digital cameras equipped with narrow band pass filters. Bands used were green at 540nm, red at 695 nm and near infra red at 790nm and 840 nm. Leaf and canopy reflectance were measured with a spectro-radiometer that scanned from 350 nm to 1050 nm with a special resolution of 1.6 nm. Aerial imaging was useful in identifying N and K stress anomalies. Crop health varies with N and K nutritional status, suggesting that aerial imaging would be a useful tool in directing producers to problem areas. Correlations were found between leaf N and K concentrations and spectral reflectance at certain wavelengths and growth stages, suggesting that remote sensing at a high degree of spectral resolution may be able to assist in the identification and mapping of field scale variability in N and K nutritional status.