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Root-zone amendments for highway right-of-way tree plantings: a demonstration project


The Texas Department of Transportation (TxDOT) and the Texas Transportation Institute’s (TTI) Environmental Management Program work with TxDOT Districts to develop roadside management practices that mitigate the highway right-of-way environment and promote healthier, more rapid plant establishment. This research study compared the effects of different root-zone soil amendments on tree establishment and growth within the highway right-of-way environment. The demonstration project site was selected at the intersection of Interstate Highway (IH) 27 at Business IH 27 in Plainview, Texas. The funding for the project was from TxDOT’s Construction Landscape Program with a design budget of $185,000. Project installation was in the spring of 1996. Results show that the majority of the trees receiving the treatment consisting of mycorrhizal inoculation, acrylamide copolymer, dry soluble yucca plant extract, soluble sea kelp extract, and humic acid had a positive response compared to the control groups and other treatment types. However, the treatment types are species specific in their overall effectiveness. Further research addressing the issues of a larger sampling of trees, more effective identification methods, and a concerted maintenance program for the demonstration site should be examined prior to making any recommendations for field application.

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