Submitted to: Agricultural and Biosystems Engineering
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/27/2007
Publication Date: 6/27/2007
Citation: Kim, Y., Reid, J.F., Han, S. 2007. On-the-go nitrogen sensing and fertilizer control for site-specific crop management. International Journal of Agricultural and Biosystems Engineering. 7(1):18-26.
Interpretive Summary: A multi-spectral imaging sensor (MSIS) system associated with a variable rate application system was evaluated for supplemental nitrogen (N) application to corn crops based on real-time N estimates derived from the MSIS reflectance responses of crop canopies. Supplemental N treatments were applied to cope with the spatial field variation based on SPAD chlorophyll meter estimates predicted from MSIS sensor response. Supplemental N treatment on the basis of real-time sensing improved the crop N status and thus could achieve the profitability of the yield production. In a view of production efficiency, the yield increase was best achieved in the plot with small amount of initial N treatments followed by the supplemental variable rate application. It was also found that any N application more than 101 kg/ha had minimal impact on yield. Profitability of the system remains to be further studied.
Technical Abstract: In-field site-specific nitrogen (N) management increases crop yield, reduces N application to minimize the risk of nitrate contamination of ground water, and thus reduces farming cost. Real-time N sensing and fertilization is required for efficient N management. An ‘on-the-go’ site-specific N management system was developed and evaluated for the supplemental N application to corn (Zea mays L.). This real-time N sensing and fertilization system monitored and assessed N fertilization needs using a vision-based spectral sensor and controlled the appropriate variable N rate according to N deficiency level estimated from spectral signature of crop canopies. Sensor inputs included ambient illumination, camera parameters, and image histogram of three spectral regions (red, green, and near-infrared). The real-time sensor-based supplemental N treatment improved crop N status and increased yield over most plots. The largest yield increase was achieved in plots with low initial N treatment combined with supplemental variable-rate application. Yield data for plots where N was applied the latest in the season resulted in a reduced impact on supplemental N. For plots with no supplemental N application, yield increased gradually with initial N treatment, but any N application more than 101 kg/ha had minimal impact on yield.