Document Type



Crop Physiology Laboratory

Publication Date

Spring 5-2003


Spectroradiometers can be used to identify plant stress by measuring crop reflectance. Spectroradiometers can measure nitrogen and water stress, and subsequent adjustments in applications can improve crop yield and reduce over-application. Two portable spectroradiometers and their accompanying software were compared for accuracy and ease of use while conducting experiments to determine water and nitrogen stress in crested wheat grass and soybean plants. The first unit was a higher priced ($40,000) visible/NIR triple diodespectroradiometer (ASD FieldSpec Pro JR) with a range of 350-2500 nm. It uses ASD’sFieldSpec Pro RS3 software. The second was a low-priced ($3600) visible/NIR fixed diode spectroradiometer (Apogee/StellarNet SPEC-PAR/NIR) with a range of 350-950 nm. It comes with StellarNet’s SpectraWiz software. The study focused on the software provided by the two manufacturers because the most noticeable differences were software-based. Comparisons were made to determine if the advantages of the ASD spectroradiometer and its software justified their substantially higher cost. The StellarNet SpectraWiz software was much more user-friendly and conveniently designed than the ASD software, which appeared outdated and time consuming to operate. However, results indicate that the ASD hardware is easier to use and simpler to configure than the Apogee/StellarNet model and that the FieldSpec Pro’s increased range was advantageous for water stress analysis. However, both spectroradiometers showed similar consistency within the 350-900 nm range.