Laser induced chlorophyll fluorescence sensing as a tool for site specific nitrogen fertilization

Current nitrogen fertilizer recommendations rely on chemical analyses of plant and soil, overlooking the in-field spatial variability of nitrogen availability. These recommendations assume uniform growing conditions across fields, yet soil mineral nitrogen and plant uptake can differ significantly, impacting crop nitrogen needs for optimal yields. Thus, nitrogen management should focus on smaller, homogeneous areas rather than treating entire fields as a single unit. This work explores a technique for monitoring plant nutritional status through remote measurements of chlorophyll fluorescence, which occurs when chlorophylls are excited by laser irradiation and release energy as fluorescence. Experiments were conducted under controlled and field conditions using both tractor-mounted and hand-held sensors to assess the reliability of these measurements for determining chlorophyll and nitrogen content, as well as biomass in wheat and maize. The study found that the F690/F730 ratio inversely correlated with chlorophyll content, allowing for the detection of nitrogen uptake and biomass across varying fertilization levels. Scanning fluorescence sensors enable simultaneous screening of multiple plants, facilitating real-time monitoring of nitrogen status and biomass. This information can be integrated with fertilization algorithms to optimize nitrogen application, enhancing crop yield and quality while minimizing environmental impact