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Erin Agro and Youbin Zheng

nitrate nitrogen (NO 3 – -N), less than 0.50 mg·kg −1 ammonia nitrogen (NH 3 -N), 7.77 mg·kg −1 P, and 168.68 mg·kg −1 K (analyzed using a saturated paste extraction method by SGS Agri-Food Laboratories, Guelph, Ontario, Canada). Polyon ® 16N–2.6P–10K

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Julie P. Newman, Joseph P. Albano, Donald J. Merhaut and Eugene K. Blythe

Release characteristics of four different polymer-coated fertilizers (Multicote, Nutricote, Osmocote, and Polyon) were studied over a 47-week period in a simulated outdoor, containerized plant production system. The 2.4-L containers, filled with high-fertility, neutral-pH substrate, were placed on benches outdoors to simulate the environmental conditions often used for sun-tolerant, woody perennials grown in the southwestern United States. Container leachates were collected weekly and monitored for electrical conductivity, pH, and concentrations of NH4 +N, NO3 N, total P, and total K. Concentrations of most nutrients in leachates were relatively high, but fluctuated frequently during the first third of the study period, and then gradually decreased and stabilized during the last 27 weeks. Osmocote often resulted in greater NH4 + and total inorganic N concentrations in leachates than other fertilizers during weeks 1 through 5, whereas Multicote produced higher NH4 + in leachates than most of the other fertilizer types during weeks 9 through 12. Overall, total P concentrations were greater with Multicote during a third of the experimental period, especially when compared with Osmocote and Polyon. Differences were also observed among treatments for leachate concentrations of K, with Polyon and Multicote fertilizers producing greater K concentrations in leachates compared with Osmocote during several weeks throughout the experimental period. Leachate concentrations of NO3 N and P from all fertilizer types were usually high, especially from week 5 through week 30.

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Eugene K. Blythe, Donald J. Merhaut, Julie P. Newman and Joseph P. Albano

Leachate from containerized substrate containing one of four different controlled-release fertilizers (Osmocote, Nutricote, Polyon, or Multicote) were monitored for concentrations of Ca, Mg, Fe, Mn, Zn, Cu, and Mo during a 47-week period. Environmental and cultural practices simulated an unheated greenhouse production program typically used for low-nutrient-requiring crops such as azalea and camellia. Leachate concentrations of all nutrients were relatively high during the first 10 to 20 weeks of the study, and then gradually decreased during the remaining portion of the experiment. Few differences were observed among fertilizer types. Of the elements monitored, only Fe and Mn leachate concentrations were above critical levels specified in the Clean Water Act by the U.S. EPA.

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Joseph P. Albano, Donald J. Merhaut, Eugene K. Blythe and Julie P. Newman

Nutrient release characteristics of four different controlled-release fertilizers (Osmocote, Nutricote, Polyon, and Multicote) were monitored during an 11-month period in a simulated outdoor nursery production facility. Although no plants were used in the experiment, fertilization rates, irrigation regimes, and cultural practices simulated those typically used to produce fast-growing, high-nutrient-requiring containerized woody ornamentals. Fertilizer prill release characteristics were monitored through analyses of leachates, which were collected weekly. Concentrations of Mg, Mn, Zn, Cu, and Mo were relatively high during the first 5 to 10 weeks of the experiment, then declined and usually stabilized during the remainder of the study. However, Mn and Zn displayed erratic increases in concentrations several times throughout the study. Calcium concentrations did not increase until the fifth week, rapidly peaked to about 300 mg·L–1, and then decreased and leveled off to ≈80 to 100 mg·L–1 during the remainder of the study. Several significant differences were observed between treatments. The Osmocote treatment had significantly greater Ca and Mg concentrations in the leachate than the other fertilizer types during the last 6 weeks of the study, whereas the Nutricote treatment often had significantly greater Fe concentrations than leachates from other treatments, especially during the last 26 to 35 weeks of the study, and significantly greater Zn concentrations than the other CRFs during the last 21 weeks of the study. Based upon U.S. Environmental Protection Agency guidelines, concentrations of Fe were often more than the allowable limit of 0.3 mg·L–1 with all fertilizer types, but especially with Nutricote. Concentrations of Mn and Cu also exceeded federal guidelines, particularly during the first several weeks of the study.

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Donald J. Merhaut, Eugene K. Blythe, Julie P. Newman and Joseph P. Albano

Release characteristics of four types of controlled-release fertilizers (Osmocote, Nutricote, Polyon, and Multicote) were studied during a 47-week simulated plant production cycle. The 2.4-L containers containing a low-fertility, acid-based substrate were placed in an unheated greenhouse and subjected to environmental conditions often used for production of azaleas and camellias. Leachate from containers was collected weekly and monitored for pH, electrical conductivity, and concentrations of NH4 + N, NO3 N, total P and total K. Leachate concentrations of all nutrients were relatively high during the first 10 to 20 weeks of the study, and then gradually decreased during the remaining portion of the experiment. Differences were observed among fertilizer types, with Multicote often resulting in higher concentrations of N, P, and K in leachates compared to the leachates from the other fertilizer types during the first half of the study. Concentrations of NO3 and P from all fertilizer types were often above permissible levels as cited in the federal Clean Water Act.

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S. Christopher Marble, Jeff L. Sibley, Charles H. Gilliam and H. Allen Torbert

-grade fertilizer 13N–5.6P–10.9K (13-13-13) at rates of 4.9 g N/m 2 (Pea1) and 9.8 g N/m 2 (Pea2), Polyon ® (Agrium Advanced Technologies, Sylacauga, AL) (8- to 9-month controlled-release fertilizer) at rates of 4.9 g N/m 2 (Poly1) and 9.8 g N/m 2 (Poly2), and

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Mary Jane Clark and Youbin Zheng

2011, almost 1 year after installation, the current study began by applying the following fertilizer treatments to the modules as outlined in Table 1 : 16N–2.6P–10K POLYON ® Homogenous NPK plus Minors, 5–6 month controlled-release fertilizer (Agrium

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Eugene K. Blythe and Donald J. Merhaut

period using Hobo external data loggers (Onset Computer Corp., Bourne, Mass.). Each container of substrate was evenly top-dressed by hand with 10 g Polyon 17N–2.1P–9.1K + micros (Pursell Technologies, Sylacauga, Ala.), a 365-d controlled

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Mary Jane Clark and Youbin Zheng

, a controlled-release fertilizer without additional P or K such as the 16–6–13 POLYON ® Homogenous NPK plus Minors used in this study, can be applied after a fall installation to establish vegetative coverage, develop plant biomass in the next season

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Gladis M. Zinati, John Dighton and Arend-Jan Both

irrigation, and with and without NERS inoculum. The fertilizer, used in this study, was a controlled-released fertilizer, Polyon ® Plus (Harrell's LLC., Lakeland, FL) 14-16-8 (14N–7P–6.6K) (6.44% nitrate N and 7.56% ammoniacal N) and commonly used by New