Abstract
Over-fertilization is a common practice in ornamental nursery production. Oftentimes, visual analysis is used to determine plant nutrient levels, leading to less accurate estimates of fertilizer application. This study focused on exploring the suitability of two non-destructive sensors, Soil Plant Analysis Development (SPAD-502) and GreenSeekerTM, for measuring plant tissue nutrient uptake. Florikan Top-Dress fertilizer 12N-6P-8K was applied to Justicia brandegeana in various increments (0, 10, 20, 30, 40, and 50 g) to simulate plants with deficient to excessive nitrogen rates. Various parameters were recorded including Normalized Difference Vegetation Index (NDVI) and SPAD readings, soil leachate analysis (nitrates and phosphate), and total leaf carbon:nitrogen (C:N). The NDVI and SPAD readings were recorded biweekly for three months after the initial controlled release fertilizer (CRF) treatments. Leaf C:N was analyzed through dry combustion while nitrates and phosphate were determined from soil leachate. Results suggest that the smaller amount (20 g) of CRF is as effective in providing N to J. brandegeana as larger amounts (30, 40, 50 g). Implementation of this fertilizer regimen will result in reduced agricultural nutrient runoff and overall negative environmental impacts. Application of optical sensor technology using SPAD and GreenSeekerTM showed promising results in determining the fertilizer requirements of J. brandegeana. This method could serve as a guideline for nursery producers and landscape personnel as a fast and non-destructive tool for sustainable fertilizer management practices within the ornamental plant industry.
Highlights
Throughout the United States, the nursery ornamental production industry has become an increasingly popular agricultural sector
Normalized Difference Vegetation Index (NDVI) values (0.82 and 0.81) were observed at 8 weeks after treatment (WAT) with 30 and 40 g fertilizer rates; there was no significant difference between these two values (Table 1)
It is possible that this decrease in NDVI is due to the additional N requirement of J. brandegeana by the 10 WAT sampling period, a crucial time for fertilizer management in nursery production (Table 1)
Summary
Throughout the United States, the nursery ornamental production industry has become an increasingly popular agricultural sector. The United States Department of Agriculture’s 15 state program has generated a cumulative monetary worth greater than four billion dollars since 2006. California and Florida account for 49% of the 15 state total value, and Florida ranks second in the total wholesale of floriculture crops at 24% of the nationwide supply, making this an economically important industry for the state [1]. Large scale nursery production involves the use of containers to grow plants with the necessary medium, usually a light weight potting mix. Producers are responsible for providing appropriate nutrients for each plant with fertilizer application depending on the targeted species and age [2]. When establishing a fertigation regime, three macro nutrients are necessary for proper plant growth; nitrogen, phosphorus, and potassium (N, P, and K, respectively) [3]. A plant that lacks the required supplement of available N (NO3 − , NH4 + ) will demonstrate various symptoms that denote feebleness
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
