Nitrogen Stress Measurement of Rape Based on Charged Coupled Device Imaging Sensor

摘要

Site-specific variable nitrogen application is one of the major precision crop production management operations. To obtain sufficient crop nitrogen stress information is essential for achieving effective site-specific nitrogen applications. This paper presents the development of a multi-spectral nitrogen deficiency sensor, which uses three channels (green, red, near-infrared) of crop images to determine nitrogen level of the rape. This sensor assess the nitrogen stress by means of the estimated SPAD value of the rape based on rape canopy reflectance sensed using three channels (green, red, near-infrared) of the multispectral camera. The core of this investigation is the calibration methods between the multi-spectral references and the nitrogen levels in crops measured using a SPAD 502 chlorophyll meter. Based on the results obtained from this study (The correlation was 0.89.), it can be concluded that a multi-spectral CCD camera can provide sufficient information to perform reasonable SPAD values estimation on-the-go during field operations.