Application of Optical Sensor Technology for Sustainable Fertilizer Management of Euphorbia Pulcherrima.

The over-use of fertilizer in the ornamental plant industry can potentially cause negative effects on human and environmental health. Euphorbia pulcherrima (poinsettia) rank second in sales for potted plants in the United States, with Florida accounting for 25%. BAM-FX is a liquid fertilizer with a specialized micronutrient delivery system that can be used alone or in conjunction with a standard NPK fertilizer. Non-destructive handheld devices Soil Plant Analytical Development (SPAD) and Normalized Difference Vegetation Index (NDVI) are optical sensors that measure the chlorophyll spectral response to light. The readings from these devices can be correlated to plant nitrogen content, and thus are good indicators for plant growth status. Growers can use this information to assess exactly how much fertilizer is necessary for optimal plant growth – without the necessity of over-application. The use of these sensors can be financially beneficial to the grower as they can assist in identifying appropriate fertilizer regimes. Various amounts of NPK fertilizer and BAM-FX were added to seven treatment groups of poinsettias. Treatments included 5.5g NPK, 2.8g NPK, 4.1g NPK, 2.8g NPK + 8mL BAM, 2.8g NPK + 16 mL BAM, 4.1g NPK +8 mL BAM, 4.1g NPK + 16 mL BAM. Optical sensor readings were taken and leachate was collected over the course of 55 days. Leaf CN was analyzed through dry combustion LECO Truspec Carbon and Nitrogen Analyzer (LECO Corporation, St. Joseph, MI) while nitrates and total phosphorus were determined from soil leachate using SEAL AQ2 Automated Discrete Analyzer. Results from this study will be used to inform poinsettia producers of best management practices for fertilizer application.