·m −2 K at 14 d after planting and were then allowed to establish for 6 weeks before treatments began. There were three fertilizer treatments: quick-release fertilizer (QRF) 16N–1.7P–6.6K (Lesco, Cleveland, OH) (ammonium sulfate, concentrated
Subhrajit K. Saha, Laurie E. Trenholm and J. Bryan Unruh
Tongyin Li, Guihong Bi, Richard L. Harkess and Eugene K. Blythe
nutrients during winter, when uptake of P, Cu, and Mn increased, whereas K and Mg uptake decreased in Rhododendron ‘Cannon’s Double’ and ‘P.J.M.’ ( Scagel et al., 2008a ). Leaf concentrations of N, K, Ca, Mg, Mn, sulfur (S), aluminum (Al), and B in bell
James T. Brosnan and Gregory K. Breeden
penoxsulam were impregnated on a granular fertilizer at 0.025% (total herbicide load = 0.05%). The analysis of the fertilizer used for impregnation was 21% N : 0% P 2 O 5 : 3% K 2 O, with N included in the form of polymer-coated urea. Fertilizer particle
Alba A. Clivati McIntyre, David M. Francis, Timothy K. Hartz and Christopher Gunter
; in the greenhouse environment, there was a direct relationship between higher K nutrition and lower incidence of color disorders ( Ozbun et al., 1967 ; Picha, 1987 ; Picha and Hall, 1981 ; Van Lune and Van Goor, 1977 ). The incidence of color
Timothy K. Broschat
Spathiphyllum Schott. 'Mauna Loa Supreme' grown for 6 months in a fine sand soil or a 5 pine bark: 4 sedge peat: 1 sand medium (by volume) were fertilized with 7.6g N, 1.4g P, and 4.5g K/3.5-liter container by 4 different methods. The same raw fertilizer prills (21N-3P-12K) were applied weekly as a liquid, monthly as soluble granules, bimonthly as a lightly resin-coated fertilizer (Osmocote), or every 6 months as a heavily resin-coated fertilizer. All leachates were collected and were measured and analyzed weekly for N O3, PO4, and K. Spathiphyllum grew best in the sand soil with either of the controlled release formula- tions, but fertilization method had no effect on growth in the potting medium. Nitrate and K leaching losses from the potting medium were lowest from the controlled release fertilizers and highest from the soluble granules. Liquid fertilization resulted in the highest amounts of PO4 lost to leaching and controlled release fertilizers the least. In the fine sand soil, NO3 leaching was equivalent from all methods. Soluble granules had the highest levels of leached K and PO4 and the lightly-coated fertilizer lost the least due to leaching.
Guochen K. Png, Katherine S. Downes and Beng H. Tan
Lechenaultia macrantha K. Krause (Goodeniaceae), commonly known as the Wreath Lechenaultia, is endemic to central, southwestern Australia ( Morrison, 1992 ). Owing to its intriguing “wreath-like” form, L. macrantha is one of the main wildflower
Timothy K. Broschat
Ixoras (Ixora L.) growing in calcareous sandy soils are highly susceptible to a reddish leaf spot disorder. Symptoms appear on the oldest leaves of a shoot and consist of irregular diffuse brownish-red blotches on slightly chlorotic leaves. Symptoms of K deficiency, P deficiency, and both K and P deficiency were induced in container-grown Ixora `Nora Grant' by withholding the appropriate element from the fertilization regime. Potassium-deficient ixoras showed sharply delimited necrotic spotting on the oldest leaves, were stunted in overall size, and retained fewer leaves per shoot than control plants. Phosphorus-deficient plants showed no spotting, but had uniformly brownish-red older leaves and olive-green younger foliage. Plants deficient in both elements displayed symptoms similar to those observed on landscape plants. Symptomatic experimental and landscape ixoras all had low foliar concentrations of both K and P.
Timothy K. Broschat
Five-gram (0.18 oz) samples of two controlled-release fertilizers (CRFs), Osmocote 15N–3.9P–10K (8–9 month) (OSM) and Nutricote 18N–2.6P–6.7K (type 180) (NUTR), were sealed into polypropylene mesh packets that were placed on the surface of a 5 pine bark: 4 sedge peat: 1 sand (by volume) potting substrate (PS), buried 10 cm (3.9 inches) deep below the surface of PS, buried 10 cm below the surface of saturated silica sand (SS), or in a container of deionized water only. Containers with PS received 120 mL (4.1 floz) of deionized water three times per week, but the containers with SS or water only had no drainage and were sealed to prevent evaporation. Samples were removed after 2, 5, or 7 months of incubation at 23 °C (73.4 °F) and fertilizer prills were crushed, extracted with water, and analyzed for ammonium-nitrogen (NH4-N), nitrate-nitrogen (NO3-N), phosphorus (P), and potassium (K). Release rates of NO3-N were slightly faster than those of NH4-N and both N ions were released from both products much more rapidly than P or K. After 7 months, OSM prills retained only 8% of their NO3-N, 11% of their NH4-N, 25% of their K, and 46% of their P when averaged across all treatments. Nutricote prills retained 21% of their NO3-N, 28% of their NH4-N, 51% of their K, and 65% of their P. Release of all nutrients from both fertilizers was slowest when applied to the surface of PS, while both products released most rapidly in water only. Release rates in water only exceeded those in SS, presumably due to lower rates of mass flow in SS.
Emily K. Dixon, Bernadine C. Strik and David R. Bryla
2012, TRUE 402 (4N–0P–2K; True Organic Products, Inc., Spreckels, CA) was applied in four equal applications at a rate of 56 kg·ha −1 N ( Harkins et al., 2013 ). Converted Organics 421 (4N–2P–1K; Converted Organics of California LLC, Gonzales, CA) was
Timothy K. Broschat
Downy jasmines [Jasminum multiflorum (Burm. f.) Andr.] and areca palms [Dypsis lutescens (H. Wendl.) Beentje & J. Dransf.] were grown in containers filled with a fine sand soil (SS) or with a pine bark-based potting substrate (PS). Each of these substrates was amended with 0%, 10%, or 20% clinoptilolitic zeolite (CZ) by volume. Plants were fertilized monthly with a water-nonsoluble 20N-4.3P-16.6K granular fertilizer. Downy jasmines were larger and had darker color in CZ-amended PS and were larger in CZ-amended SS than in nonamended SS or PS. Areca palms, which tend to be limited by K in SS had better color and larger size when the SS was amended with CZ. In PS, where K is seldom limiting, areca palms did not respond to CZ amendment of the PS. Both ammonium (NH4)-N and potassium (K) were retained against leaching by CZ, but some of the NH4-N adsorbed to CZ was subject to nitrification, either before or after its release into the soil solution. Some phosphate (PO4)-P was also retained by CZ.