Abstracts

CORLEY, W.L. 1984. Re-evaluating the value of amending planting holes with organic material. Am. Nurseryman 1 59(6): 113-116.

For more than two centuries the ideal planting hole for landscape shrubs and trees was considered to be one that had been organically amended to provide optimum rhizosphere conditions, thereby enhancing root development and plant growth. However, a search of literature on the subject reveals that this practice is based on custom and apparent logic rather than research data. Since 1975, the Georgia Agricultural Experiment Station, Experiment, Georgia, has been the site of three major tests to determine the value of organically amended backfill in Cecil clay. Researchers followed customary cultural installation and maintenance practices of fall planting, adding fertilizer to the planting holes regularly, liming acid soils, irrigating, and mulching. Increasing a hole’s size produced more growth than using backfill amendments. Azalea, holly, shore juniper, and white dogwood did not respond significantly to backfill amended with pine bark during three growing seasons. The highest mortality rates in all species occurred in amended holes, whether mulch was present or not.

• © 1985, International Society of Arboriculture. All rights reserved.