When we were first researching and designing the Silva Cell, Tom Smiley, PhD set up a research plot* at the independent Bartlett Tree Laboratory in Charlotte, NC. We were confident about the design principles used in the construction of the Silva Cell, but also wanted to measure exactly how it held up against competitive products like structural soil, gravel, stalite, and regular or compacted soil. Tom, a tree expert, is always testing new technologies to see how they hold up to scrutiny.
The research plots were set up so that that 12 trees planted grown in a suspended pavement system (which is identical in performance to the Silva Cell), 12 trees were planted in a stalite/soil mix, 12 trees were planted in compacted soil, 12 trees in pure stalite, and 12 trees in a gravel/soil mix. All trees had access to 189 ft3 of growing medium.
The research is ongoing — we plan to monitor the plots for at least 10 years, if not more — but the preliminary results show that the Silva Cell growing conditions very quickly foster healthier, stronger tree growth when compared to leading competitors. Take a look at the pictures.
At 14 months
At 2.4 years
At 3.5 years
At 4+ years
At 5.5 years
E. Thomas Smiley’s report from 2006 on this study states that “The trees in the noncompacted/suspended pavement treatment were larger, faster growing, had better color, and more root growth than most of the other treatments… The differences in tree growth among treatments was dramatic; trees growing in the noncompacted soil suspended pavement treatment are visually healthier in appearance and provide more shade more quickly than any of theother treatments.”
* Bartlett Tree Lab study is not a Deep Root study. Bartlett is an independent lab that chooses their own test parameters, conditions, and technologies. Deep Root did not influence, pay for, or at any point become involved in the planning or design of that study. We also have no sway over the results, which we expect Tom Smiley to continue to publish about over the coming years.