Non-Destructive Handheld Sensors for Sustainable Fertilizer Management of Justicia Brandegeana.

Excessive application of fertilizer is common practice in nursery production. Oftentimes, visual analysis is used to determine plant nutrient levels, which in many cases can lead to inaccurate estimates. Nitrogen is an essential component of chlorophyll in plant leaves and a major component of all amino acids. Nitrogen (N) is directly correlated with leaf area/weight and overall plant size. Deficiencies lead to loss of productivity and overall value of a plant. FLORIKOTE TOP-DRESS fertilizer 12N-6P-8K (Florikan Top Dress 12-6-8 60 Series) is a polymer coated, slow-release fertilizer that claims to supply available nutrients for 2-3 months after application. This study focused on the application of FLORIKOTE to Justicia brandegeana (shrimp plant), measuring nutrient uptake by Soil Plant Analysis Development (SPAD), Normalized Difference Vegetation Index (NDVI), soil leachate (nitrates & total phosphorus), and total carbon/nitrogen. Justicia brandegeana was selected due to its economic importance as an ornamental in South Florida and throughout hardiness zones 8-10 of the United States. Various fertilizer treatments (0, 20, 30, 40, and 50 g) were applied to simulate symptoms of plants with deficient or excessive nitrogen amounts. Normalized Difference Vegetation Index (NDVI) and Soil Plant Analysis Development (SPAD) readings were taken biweekly for 4 months after adding initial fertilizer treatments. 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. The information gathered will be used to inform nursery producers on an optimal fertilization regime that can be followed for this ornamental plant which is in high demand throughout South Florida.