Five 12- to 14- month slow release fertilizers (Osmocote 17-7-12, Sierra 16-6-10, High-N 24-4-7, Sierrablend 17-7-10, and Nutricote 16-10-10 Type 360) were incorporated into a 3:1 pine bark: peat moss potting medium at one of 4 rates (0.9, 1.2, 1.5, and 1.8 kg N/m3). Plant growth of 3 azale a species, `Coral Bells' (Kurume), `Formosa' (Southern Indica), and `Pink Gumpo' (Satsuki), and monthly medium solution electrical conductivity (EC) were determined. Growth indices 180 days after applying fertilizer were greatest for plants receiving the Sierrablend and Osmocote fertilizers regardless of azalea species. Plant growth indices increased as N rate increased for the 3 azaleas, regardless of the fertilizer product. The highest media solution EC readings occurred during the first 90 days after fertilizer application for all fertilizer treatments and declined thereafter.
Joseph Eakes and John W. Olive
D. Joseph Eakes and John W. Olive
Two 8- to 9- month [Nutricote 20-7-10 (Type 270) and Osmocote 18-6-121 and two 12- to 14- month [Nutricote 20-7-10 (Type 360) and Osmocote 17-7-121 controlled release fertilizers were preplant incorporated into a 3:1 pine bark:peat moss medium during two potting dates (April 12 and June 6, 1991) at the rate of 1.5 kg N/m. Plant growth of two woody ornamentals, 'Green Luster' Japanese holly and 'Fashion' azalea, and monthly medium solution electrical conductivity (EC) were determined. Growth index [GI = (height + width at widest point + width perpendicular to widest point)/3] response to fertilizer treatment was species specific. Nutricote 20-7-10 (type 360) produced the largest GIs for holly, while GIs for azalea were not affected 420 days after initiation (DAI) of the test. Plants potted in April had greater GIs than those potted in June for the two plant species 420 DAI, regardless of fertilizer type. Osmocote 18-6-12 and 17-7-12 controlled release fertilizers had the greatest medium solution ECs from 90 to 180 DAI.
Ken Tilt, Charles H. Gilliam, and John W. Olive
Lagerstroemia × `Natchez' and Quercus virginiana were planted into a sandy loam soil in grow bags and by traditional field planting methods. After 2 years in the field, 1 sample from each of 6 replications was dug from the field in March. Root and top growth were measured. Half the remaining plants were dug and transplanted into 76 liter containers for 3 months. Growth indices were measured at this time. The remaining trees in the field were dug in July and handled similarly. Data from live oak trees showed increased height in trees produced by traditional field planting methods. No differences between planting methods were found in any other growth indices for the two species. Both crapemyrtle and live oak trees transplanted from traditional field plantings in March had greater height than trees transplanted from grow bags. However, no differences were detected for top weight, caliper or root ratings. July transplanted crapemyrtles showed no differences in any of the growth indices. Live oaks transplanted in July from traditional field plantings to containers all died with no additional growth. Grow bag transplanted oaks survived and continued to grow.
Ken Tilt, William D. Goff, David Williams, Ronald L. Shumack, and John W. Olive
Pecan [Carya illinoinensis (Wangenh.) C. Koch `Melrose'] and pear (Pyrus calleryana Decne. `Bradford') trees in the nursery grew more in containers designed to hold water in the lower portion. The water-holding reservoir was obtained either by placing 76-liter containers in a frame holding water to a depth of 6 cm or by using containers with drainage holes 6 cm from the bottom. Continuous waterlogging at the bottom of containers resulted in root pruning and root death in the lower portion of the containers, but roots grew well above the constantly wet zone. Fresh weight of plant tops and trunk diameters were greater after two growing seasons in the containers with water reservoirs compared to those grown in similar containers with no water reservoirs. Total root dry weight was unaffected.
Donna C. Fare, Charles H. Gilliam, Gary J. Keever, and John W. Olive
Two experiments were conducted to evaluate the effects of cyclic irrigation on leachate NO3-N concentration, container leachate volume, total effluent volume, and growth of Ilex crenata Thunb. `Compacta'. In Expt. 1, container leachate volume was reduced 34% when 13 mm of water was applied in three cycles compared to continuous irrigation of 13 mm per unit time. Forty-nine percent less container leachate volume was collected from a continuous application of 8 mm than from that of 13 mm water. In Expt. 2, container leachate volume was reduced 71% when 6 mm was applied in a single application over 30 minutes compared to 13 mm applied continuously for 1 hour. Total effluent was reduced by 14% and 10% in Expts. 1 and 2, respectively, when 13-mm irrigation was applied in three cycles compared to one continuous irrigation. Container leachate NO3-N concentrations from cyclic irrigation were generally less than leachate NO3-N concentrations from continuous irrigation treatments. The percentage of applied N leached as NO3-N ranged from 46% when 13-mm irrigation was applied in three cycles to 63% when 13-mm irrigation was applied in a single cycle. Leachate NO3-N concentration was reduced as irrigation volume was reduced from 13 to 6 mm in Expt. 2. Percentage of applied N leached as NO3-N was 63%, 56%, and 47% when 13-mm irrigation was applied in one, two, and three cycles, respectively, compared to 19%, 16%, and 15% when 6-mm irrigation was applied in one, two, and three cycles, respectively. `Compacta' holly shoot and root growth were minimally affected by cyclic irrigation or irrigation volume.