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  • Author or Editor: Diane Weigle x
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Columns (4 × 15 cm) of a pine bark medium amended with the equivalent of 4.2 kg per cubic meter of dolomitic limestone and either 0, 2.4, 4.7, 7.1 or 9.5 mg of urea-formaldehyde (38% N) per cubic centimeter of medium were leached daily with 16 ml of deionized water (pH 5.5). Leachate total N, NO3 --N and NH4 +-N concentrations were determined on day 1, 3, 5, 7, 14, 28, 49, 91, 133, 203, 273 and 343. Leachate total N ranged from 600 ppm on day 1 for the 9.5 mg treatment to 4 ppm on day 273 for the 2.4 mg treatment. Leachate NH4 +-N concentrations ranged from 38 ppm c4 day 3 for the 9.5 mg treatment to less than 1 ppm on day 7 for the 2.4 mg treatment and were less than total N concentrations at each sampling time. Leachate NO3 --N was not detectable during the experimental period. Eleven, 16, 20 and 25% of the applied N leached from the columns amended with 2.4, 4.7, 7.1 or 9.5 mg of urea-formaldehyde per cubic centimeter of pine bark, respectively, during the 371 day experiment.

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Columns (4 × 15 cm) of incubated (25C, 7% volumetric moisture) milled cypress [Taxodium distichum (L.) L. Rich] wood chips received 180 mg of each ionic form of N applied to the surface from dry NH4NO3, KNO3, or (NH4)2SO4 and were leached daily with 16 ml deionized water (pH 5.5). After 10 days, >85% of applied N leached from the columns in all treatments. After 25 days, all N leached from the NH4NO3 and KNO3 treatments, and 93% leached from the (NH4)2SO4 treatment. In subsequent experiments, columns received 360 mg N from NH4NO3 and were leached daily with either 16, 32, 48, or 64 ml of deionized water for 50 days. The rate of N leaching increased with increasing water application rate, although total N leached per column was similar for all water rates after 25 days. Columns that received 45, 90, 180, or 360 mg N/column were leached daily with 16 ml of deionized water. Nitrogen concentrations in the leachate ranged from 3406 ppm NO 3 -N and 2965 ppm NH 4 + -N at day 5 for the 360-mg rate to 3 and 5 ppm, respectively, at day 35 for the 45-mg rate. In all experiments with NH4NO3, more NO 3 -N leached than NH 4 + -N and more NO 3 -N leached than applied, indicating vitrification occurred. NH 4 + -N and NO 3 broadcast over cypress wood chips in the landscape would leach quickly into the soil.

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Dwarf burford holly (Ilex cornuta `Burfordii Nana') fertilized with N at 22.1 g per container yearly during production in the nursery generated more new shoot weight but less root weight after transplanting to a landscape than those receiving N at 14.8 g per container yearly. Slicing the root ball at planting, compared to not slicing, resulted in comparable regenerated root weight but reduced new shoot number, new shoot dry weight, and new shoot:regenerated root dry-weight ratio when irrigation was not applied daily after transplanting. Although irrigation frequency did not impact total weight of regenerated roots into landscape soil, more roots grew from the bottom half of the root ball when plants were irrigated periodically after planting than when plants received daily irrigation. Plants irrigated other than daily produced fewer shoots and less shoot weight than those receiving irrigation daily after transplanting. When plants were without irrigation for 4 or 6 days in the first week after transplanting, those planted without the nursery container on the root ball were more stressed (more negative xylem potential) than those planted with the container still on the root ball. However, 2 weeks later, plants without the nursery container were less stressed due to root growth into landscape soil.

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