Benefits of Small-Prill Controlled-Release Fertilizer in Container Production
Microprill fertilizer granules (<1.0 mm width) were incorporated into soilless media at a 2 lb/yd3 (1.2 k/m3) rate and compared with an operational standard of 6 lb/yd3 (3.6 k/m3) incorporation of a standard-size prill (>2.4 mm/0.09 in width). Micro prill counts per cell averaged 5.0, 7.8 and 9.4 times higher than standard-sized prill counts for 2, 10 and 15 cu in (207A, 415D and 515A) Stuewe styroblock containers (Stuewe & Sons, Inc 2014), respectively. Coefficients of variation of micro prills per cell were 3 times lower across container sizes compared with standard-sized prills per cell. These results demonstrate the potential for micro prills to improve crop uniformity through decreased fertilizer variability. A separate study evaluated the effectiveness of iron sulfate prills in inhibiting moss and liverwort establishment on a bark and peat-based medium. Standard-sized prills of 90- and 180-day release patterns were top dressed at rates of 25 lb and 50 lb per 1,000 ft2 (122 and 244 kg per 1,000 m2) along with an untreated control. After 12 weeks, the 50 lb (244 kg) rate of 180-day release had the lowest moss coverage at 24% compared to 57% coverage for the untreated control. A second trial compared 75 lb per 1,000 ft2 (366 kg per 1,000 m2) top-dressing of three iron sulfate controlled release fertilizer products (standard size prills of 90- and 180-day release patterns and a mini-sized prill of 90-day release pattern) and an untreated control. After 12 weeks, the combined moss and liverwort coverage was 78% for the untreated control, while the mini-size prill treatment was significantly lowest at 7% coverage. These trials demonstrate that controlled-release iron sulfate can prevent moss and liverwort establishment when applied at an adequate rate using a mini-sized product that allows for even product distribution.
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Author(s): Nabil Khadduri
Publication: National Nursery Proceedings - 2013
Event:
Western Forestry and Conservation Nursery Association Meeting
2013 - Olympia, Washington
