month duration of their study. Gilman Effects of Fertilizer Type and Rate on the et al. (2000) also did not observe Quality and Nutrient Content of Four Species of differences among treatments in the growth of southern magnolia (Magnolia Trees Growing in Sandy South Florida Soils grandiflora) during the first year after planting, but treatment differences were 1 significant after 3 and 4 years. On the Timothy K. Broschat other hand, fertilized live oak (Quercus virginiana) were larger than unfertilized ADDITIONAL INDEX WORDS. Quercus virginiana, Swietenia mahagoni, Bucida trees during their first year (Gilman buceras, Calophyllum brasiliense, live oak, west indian mahogany, black olive, et al., 2000). beautyleaf, principal component analysis Most fertilizer studies on trees have concentrated on N require- SUMMARY. Broadleaf ornamental trees are known to vary widely in their responses to ments, yet in Florida landscapes N fertilization, depending on the species and soil and other environmental factors. Thus, it is important to study the responses of a wide range of tree species to deficiency symptoms are seldom ob- fertilization, especially on nutrient-poor soils. Four species of temperate to tropical served. Magnesium deficiency is fairly trees, live oak (Quercus virginiana), west indian mahogany (Swietenia mahagoni), common on Florida trees (Dickey, black olive (Bucida buceras ‘Shady Lady’), and beautyleaf (Calophyllum brasiliense), 1977), but it is not known if routine planted into a sandy native soil in south Florida were fertilized with a 24N–0P–9.3K application of magnesium (Mg) or turf fertilizer or an 8N–0P–10K–4Mg plus micronutrients palm fertilizer at rates of micronutrient-containing fertilizers 10 or 20 g of nitrogen per tree four times per year. Tree height, width, caliper, and would result in superior growth or nutrient deficiency rating scores for nitrogen, potassium, and magnesium were visual quality. Gilman et al. (2000) determined at 1 year after planting (establishment period) and at 3 years after found no response to applied phos- planting (maintenance phase). Data from these measured variables were subjected phorus (P) or potassium (K) in live to principal component analysis to obtain a single measure of overall quality, namely, the scores for each tree on the first principal component. West Indian oak, but this species rarely exhibits mahogany showed no response to fertilization during or following establishment. deficiencies of any nutrient element in Either fertilizer type or rate improved live oak, black olive, and beautyleaf quality the landscape. over that of unfertilized controls during both establishment and maintenance Because responses to fertilization phases, but the high rate of the palm fertilizer was superior to either rate of the turf appear to vary greatly among species fertilizer for beautyleaf both during establishment and afterward. Leaf nutrient and in different soils and environ- concentrations generally were poorly correlated with overall tree quality, but ments, it is important to study the manganese concentrations differed significantly among treatments for all four growth responses of individual spe- species. Based on these results, fertilization of West Indian mahogany is not cies, especially on nutrient-poor soils. recommended, but live oak, black olive, and beautyleaf will benefit from fertilizer The purpose of this study was to applied at the time of planting and after establishment. determine how four trees commonly grown in south Florida respond to he response to fertilization of and much of that has used chinese two commercially available types of newly planted trees, as well as hibiscus (Hibiscus rosa-sinensis), a spe- fertilizer, a typical turf fertilizer that Testablished trees, appears to cies that may be atypical for tropical contains no Mg or water-soluble vary greatly depending on time since and subtropical trees because of micronutrients and a palm fertilizer transplanting, species, soil type, cli- its high nitrogen (N) requirements that contains large amounts of K, Mg, mate, method of application, and type (Broschat and Moore, 2010; Gilman, and soluble micronutrients, and to of fertilizer (Struve, 2002). Fertilizer 1987, 1988). determine if fertilizer rate is important, recommendations for deciduous trees Fertilizer requirements for trees both during and after establishment. growing in loam or clay soils in tem- during the first year after transplant- perate climates would not be expected ing may be different from that of Materials and methods to be appropriate for evergreen species established trees. Gilman and Yeager Trees grown in 10-L polypropyl- growing in sandy soils in subtropical (1990) did not notice significant dif- ene containers were transplanted into climates such as that of peninsular ferences in growth between fertilized a Margate fine sand soil (siliceous, Florida. Relatively little research has and unfertilized laurel oak (Quercus hyperthermic Mollic Psammaquent, been published on fertilizer require- laurifolia) during the short 17- pH 5.2) in Davie, FL, on 5 June ments of trees in sandy soils of Florida Fort Lauderdale Research and Education Center, Units University of Florida, 3205 College Avenue, Davie, To convert U.S. to SI, To convert SI to U.S., FL 33314 multiply by U.S. unit SI unit multiply by This research was supported by the Florida Agricul- 0.3048 ft m 3.2808 tural Experiment Station and by the USDA National 2 2 Institute of Food and Agriculture Hatch project FLT- 0.0929 ft m 10.7639 FTL-004945. 3.7854 gal L 0.2642 2.54 inch(es) cm 0.3937 I thank Susan Thor and Andy Fu for their assistance in 2 Á –2 this study. 4.8824 lb/1,000 ft g m 0.2048 10 meq/100 g mmolÁkg–1 0.1 1 Corresponding author. E-mail: tkbr@ufl.edu. 28.3495 oz g 0.0353 doi: 10.21273/HORTTECH03864-17 1 ppm mgÁg–1 1 • December 2017 27(6) 813 RESEARCH REPORTS 2012. Soil samples (n = 6) taken at the the black olive trees so all trees of this component typically contains high time of planting showed a mean or- species, including controls, received positive correlations for most or all ganic matter content of 5.0%, cation 40 g of triple superphosphate (0N– of the original variables with the first exchange capacity of 7.5 meq/100 g, 18.8P–0K) fertilizer [0–43–0 (Helena principal component, making it a use- available phosphorus P (P1) of 9.0 Chemical, Ft. Pierce, FL)] every 3 ful index of overall quality. These ppm, K averaged 16.3 ppm, Mg 35.8 months. In Jan. 2014 this amount scores for each tree on the first prin- ppm, and calcium (Ca) 2308 ppm. A was increased to 160 g/tree spread cipal component were further sub- randomized complete block design over a 4-m2 area surrounding each jected to analysis of variance (PROC was used with trees spaced 3 m apart tree. This P fertilization was done to GLM) with mean separation by the in linear blocks separated from other prevent the effects of P deficiency Waller–Duncan k-ratio method (P = blocks by a distance of 5 m in all from confounding tree responses to 0.05) to determine treatment effects. directions. There were eight replicate the fertilizer treatments, none of At the end of the experiment (12 blocks containing one plant of each which contained any P. Dec. 2015), leaf samples consisting of species for each treatment. Species All trees received 2cmof the youngest fully expanded leaves on used were live oak, west indian ma- water from overhead irrigation each shoot were collected from each hogany, black olive, and beautyleaf, three times per week during the tree for nutrient analysis. Leaf samples four of the most common large tree first 6 months and twice per week were dried, ground, and digested species planted in south Florida. thereafter. An area of 1m2 around using a modified Kjeldahl procedure Fertilizers were applied at the all trees was kept weed-free with (Hach et al., 1987), and they were time of transplanting and every 3 glyphosate. Minimal pruning was analyzed for N using an autoanalyzer months thereafter for 3 years. Treat- periodically done to establish (Seal Analytical, Mequon, WI), P by ments included 1) no fertilizer strong central leaders and good the ascorbic acid method (Kuo, (CONTROL), 2) a 24N–0P–9.3K branch structure. All trees were 1996), and K, Mg, Fe, and Mn by turf fertilizer [24–0–11 (Lesco, measured at the time of transplant- atomic absorption spectroscopy Cleveland, OH)] applied at a rate of ing and every year thereafter for (Perkin-Elmer, Waltham, MA). Leaf 41.7 g/tree, 3) the same turf fertilizer total height, width in two opposite nutrient concentration data for each applied at 83.4 g/tree, 3) a 8N–0P– directions (parallel and perpendic- element were analyzed using analysis 10K–4Mg plus micronutrients palm ular to rows), and stem caliper at of variance with mean separations by fertilizer [8–0–12 (Nurserymen’s 30 cm above the ground. The two the Waller–Duncan k-ratio method Sure Gro, Vero Beach, FL)] applied width measurements were averaged as used for plant quality data. Pearson at 125 g/tree, and 4) the same palm to obtain a single value. Growth correlation coefficients were calculated fertilizer applied at 250 g/tree. The was calculated as the height at the for all tree quality and leaf nutrient turf and palm fertilizer application end of 1 year (establishment pe- concentration variables using PROC rates provided equivalent amounts of riod) minus initial height. Growth CORR. N equal to 10 and 20 g/tree of N per during the maintenance phase was application for the low and high rates, calculated as the final height after 3 Results and discussion respectively. Fifty percent of the N in years minus the height at the end of A summary of the principal com- the turf fertilizer was in controlled- the establishment phase.