Abstract
To develop a controlled-release fertilizer (CRF) suitable for nutrient absorption characteristics of Phalaenopsis, four kinds of new controlled-release fertilizer (NCRF 1–4) with different dissolution rates were developed and studied to determine the concentration and amount suitable for growth of Phalaenopsis. To make NCRF, new acryl-based polymers were developed and used as fertilizer coating solutions. In addition, a fluidized bed coater for coating fertilizer was developed and used in this study. To test the growth of Phalaenopsis, 10-month-old Phalaenopsis seedlings were planted in plastic pots (diameter 10 cm) filled with 100% Sphagnum moss and cultivated for approximately 100 days from May 29, 2015, to September 11, 2015. NCRF 1, NCRF 2, and Osmocote, an imported fertilizer, consistently exhibited release patterns of fertilizer nutrients in a directly proportional form; however, NCRF 3 and NCRF 4 displayed a sigmoid-like tendency of fertilizer nutrient release with a slower initial dissolution rate. Furthermore, leaf length, leaf width, fresh weigh, and root weight of Phalaenopsis were the highest when growing in 1.5 g/pot of NCRF 3 fertilizer, and the pH and electrical conductivity (EC) of the soil were stable at this concentration of NCRF 3. Based on our results, we suggest that 1.5 g/pot of NCRF 3 fertilizer is the ideal concentration and fertilizer for growing Phalaenopsis.
Highlights
Controlled-release fertilizer (CRF) is a fertilizer manufactured with an insoluble coat covering the surface of watersoluble fertilizer pellets [1]
The dissolution rate test was conducted in sphagnum moss, which is similar to the growth environment of Phalaenopsis in which CRF will be used as a fertilizer
NCRF 1 and NCRF 2 had faster release rates, and NCRF 3 and NCRF 4 exhibited slower release rates compared to Osmocote
Summary
Controlled-release fertilizer (CRF) is a fertilizer manufactured with an insoluble coat covering the surface of watersoluble fertilizer pellets [1] It has the benefit of reducing fertilizer-induced pollution because fertilizer nutrients are gradually eluted through a semipermeable film as needed by crops [2]. The use of CRF has sharply increased because the release speed of fertilizer nutrients can be adjusted to approximately 3–12 months by controlling the material and thickness of the coating. Two kilograms of granular complex fertilizer with a particle size of 2–4 mm was placed in the fluidized bed coater, and the granular compound fertilizer was floated to the air at a flow rate of approximately 200 m3/h and flow air temperature of 60 °C. The raw materials used for manufacturing NCRF were conventional fertilizer 18(TN)-17(P2O5)-15(K2O) ? TE, and only 2–4 mm size was
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