Calibration Ramps for Reflectance-Based Nitrogen Management in Cotton

The  ramped calibration strip technology applies increasing levels of N in a strip across 320 ft. with  20 ft. steps of 10 lbs of N per acre increments.  The levels applied ranged from 0 at the start of the strip to the maximum of 160 lbs of N, this fertilizer is applied in a very early crop growth stage.  Twenty ramps were set up in farmers fields and and crop reflectance observations were recorded with hand-held sensor by walking down the strip, every alternate week starting at the first square stage.