May’s issue of Arboricultural Consultant, the magazine of the American Society of Consulting Arborists (ASCA) has side-by-side articles by James Urban, FASLA, and Nina Bassuk, Ph.D. discussing different methods for providing trees with soil underneath paving. Jim’s article is on “Comparing Silva Cells and Structural Soil,” and Nina’s is on “The Why’s and How’s of Using CU-Structural Soil to Grow Trees in Pavement.”
The articles each have their own structure and address different points, but you’ll find information in both on some of the most commonly concerns that will help clarify the differences between the two products. Questions about pH, comparisons of net soil volume, water harvesting and availability, rainwater applications, sustainability, cost, maintenance, and lessons learned are all covered.
We’re hoping that the magazine will run a subsequent article by a third party researcher who can unpack the differences between the two even further. In the meantime, you can download Jim and Nina’s articles here.