PORTABLE, NEAR-INFRARED SPECTROPHOTOMETER FOR RAPID SOIL ANALYSIS

A portable, near-infrared spectrophotometer was designed, fabricated, and performance tested Significant features included a circular variab le filter monochromator, a fiber optic coupling for sensing of remote samples, and a software algorithm which corrected the instrument readi ngs to a zero baseline. The instrument had a sensing range of 1650 nm to 2650 nm, an optical bandwidth of under 55 nm, and could acquire a s pectrum every 200 ms. The intended use of this device was for rapid es timation of soil organic matter as a control input for variable rate h erbicide application.