Arboriculture & Urban Forestry 33(2): March 2007 117 Table 2. Red maple (Acer rubrum) P values of a priori contrasts for cross-sectional trunk area growth for 3 years after transplanting, shoot extension (mean of five shoots per replication) for 2 years after transplanting, and leaf nitrogen content (pooled sample of five leaves per replication) the third year after transplanting. Trunkz growth 2000 Contrasts Trunk growth 2001 Trunk growth 2002 Shooty extension 2000 P>F Irrigated, fertilized at planting vs. not fertilized at planting (FSPI vs. FSI) 0.158 0.757 0.013 0.093 Not irrigated, fertilized at planting vs. not fertilized at planting (FSP vs. FS) 0.339 0.598 0.959 0.562 Irrigated, spring fertilization vs. fall fertilization (FSI vs. FFI) Irrigated, fertilized vs. not fertilized (FSPI, FSI, FFI vs. NFI) 0.147 0.799 0.014 0.257 0.431 0.617 0.624 0.592 Fertilized, irrigated vs. not irrigated (FSPI, FSI, FFI vs. FSP, FS, FF, FSp) 0.604 0.081 0.123 0.966 Not fertilized, irrigated vs. not irrigated (NFI vs. NF) Not irrigated, spring fertilization vs. 1 Not irrigated, fall fertilization vs. 1 ⁄2 ⁄2 spring + 1 spring + 1 ⁄2 ⁄2 fall (FS vs. FSp) fall (FF vs. FSp) Fall fertilization vs. spring fertilization (FSI, FFI vs. FS, FF) 0.362 0.418 0.495 0.717 0.312 0.986 0.396 0.190 0.758 0.348 0.690 0.267 0.606 0.371 0.139 0.515 zContrasts are for rate of change from multivariate repeated measures analysis of variance (n 6). yn 6 with five subsamples per replication. xNitrogen content is percent of dry weight (n 4). spread is 1.5 to 2 times tree height) would have a root system ground surface area between 10.4 and 18.6 m2 (112 to 201 ft2). Thus, when fertilization is based on ground surface area of the root system, a tree that has not been transplanted would receive roughly 20 to 40 times as much fertilizer as the same tree after transplanting. One possible reason for the lack of tree response to fertilization in the current study is that the recommended rates simply do not provide a sufficient quan- tity of fertilizer in this scenario to produce a measurable response. There is little evidence in the literature of high N rates damaging transplanted trees. Bare root liners receiving as much as 32.8 g N/m2 (6.7 lb N/1000 ft2) did not appear damaged by these high rates; although one of the three spe- cies studied did show reduced growth in the first year, this effect disappeared in the second year (Wright and Hale 1983). There is evidence that in some situations, optimum N application rates for growth of established shade trees may be anywhere from 29.3 g N/m2 (6 lb N/1000 ft2) to 58.6 g N/m2 (12 lb N/1000 ft2) (see Struve’s discussion [2002] of research by Neely, Himelick, and Crowley [Neely et al. 1965, 1970]). Gilman et al. (2000) found increases in tree height for con- tainer-grown magnolias fertilized in the landscape at a rate of 40 g N/m2 (8.3 lb N/1000 ft2) over those fertilized at only 20 g N/m2 (4.2 lb N/1000 ft2). All of these rates are considerably higher than current recommendations. Nonetheless, there are Table 3. Littleleaf linden (Tilia cordata) P values of a priori contrasts for cross-sectional trunk area growth for 3 years after transplanting, mean shoot extension (mean of five shoots per replication) for 2 years after transplanting, and leaf nitrogen content (pooled sample of five leaves per replication) the third year after transplanting. Trunkz growth 2000 Contrasts Trunk growth 2001 Trunk growth 2002 Shooty extension 2000 P>F Irrigated, fertilized at planting vs. not fertilized at planting (FSPI vs. FSI) 0.308 0.288 0.569 0.558 Not irrigated, fertilized at planting vs. not fertilized at planting (FSP vs. FS) 0.757 0.432 0.288 0.222 Irrigated, spring fertilization vs. fall fertilization (FSI vs. FFI) Irrigated, fertilized vs. not fertilized (FSPI, FSI, FFI vs. NFI) 0.763 0.892 0.514 0.621 0.588 0.793 0.362 0.716 Fertilized, irrigated vs. not irrigated (FSPI, FSI, FFI vs. FSP, FS, FF, FSp) 0.333 0.084 0.276 0.240 Not fertilized, irrigated vs. not irrigated (NFI vs. NF) Not irrigated, spring fertilization vs. 1 Not irrigated, fall fertilization vs. 1 ⁄2 ⁄2 spring + 1 spring + 1 ⁄2 ⁄2 fall (FS vs. FSp) fall (FF vs. FSp) Fall fertilization vs. spring fertilization (FSI, FFI vs. FS, FF) 0.840 0.394 0.607 0.019 0.248 0.812 0.937 0.306 0.336 0.036 0.470 0.701 0.725 0.212 0.360 0.916 zContrasts are for rate of change from multivariate repeated measures analysis of variance (n 6). yn 6 with five subsamples per replication. xNitrogen content is percent of dry weight (n 4). ©2007 International Society of Arboriculture 0.184 0.533 0.558 0.343 0.160 0.914 0.787 0.547 0.840 0.880 0.603 0.499 0.433 0.251 0.102 0.027 0.021 0.574 Shoot extension 2001 Leafx nitrogen 2002 0.438 0.392 0.654 0.370 0.179 0.065 0.521 0.339 0.602 0.373 0.209 0.117 0.190 0.193 0.612 0.700 0.626 0.606 Shoot extension 2001 Leafx nitrogen 2002
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