Q: I recently got into a conversation with someone who claimed soils are a renewable resource because the nutrients in them can be replaced with fertilizers. But I’ve heard that soil takes a really long time to form, so that to me makes it non-renewable. What’s your opinion? A: The idea that soil is renewable… More
We write a lot about the benefits that trees and soils have on water quality. But what, exactly, do they improve? Back in 2011, landscape Nathalie Shanstrom tackled this topic, explaining in easy-to-understand terms what we mean by when we refer to water quality improvements. While seriously impaired runoff is not a concern on most sites,… More
A recent issue of the Ontario Association of Landscape Architects (OALA) magazine, Ground, contained a great discussion between nine professionals on the topic of soil. James Urban, FASLA, ISA, wrote to the magazine to add a few more comments to the piece – taking issue with the contention that what we plant in shouldn’t be… More
Last year, Jim Urban wrote a post for this blog entitled Against Mulch. The principle reasons he cited for his position were: 1) Mulch floats and can clog drains and releases “lots of phosphorus” as it breaks down, and 2) work by Gilman et al. that suggest that mulch does not reduce evapo-transpiration. We discussed… More
We love trees. We also love woodies. For those of you who have been reading this blog for a while, you will know that we promote large volumes of non-compacted, biologically active loam as essential for street tree health and longevity. There are other plants which require soil volume and need attention as well. Vines,… More
How do the stormwater benefits of Silva Cell suspended pavement tree/soil systems compare to the stormwater benefits of traditional bioretention systems? Since the mechanisms by which the tree and soil provide the stormwater benefits in these systems are the same as those in traditional bioretention, we expected the benefits to be comparable as well. The… More
There is a lot of misinformation in the landscape architecture community about whether or not trees roots will grow in gravels, structural stone soils, and clear stone. Our experience indicates that roots will adventitiously grow in any medium given the right set of circumstances. Quantifying and predicting what set of circumstances produce that growth response… More
For the last two weeks in December I’m be re-posting some of my favorite blog posts from this year. Today’s shares some of the most exciting news we got in 2013, when the Washington State Department of Ecology recognized the Silva Cell as being functionally equivalent to a rain garden. Scroll all the way to the… More
Many factors affect tree health. Are they all equally important or are some more important than others? According to Kim Coder, soil compaction is by far the biggest constraint on tree growth. In a 2007 paper, he wrote, “Soil compaction is the most prevalent of all soil constraints on shade and street tree growth…Many people… More
Tim O’Hare Associates LLP is a leading independent environmental consultancy based in the United Kingdom specializing in soil science and landscape engineering, including soil science, topsoil, habitat creation, sales pitch agronomy, and more. A few weeks ago I talked to Tim O’Hare himself to learn more about its reuse, recovery, and what it really means… More
A large-canopy tree is a very beautiful thing. On this, most people will agree. But is not only beautiful—it also benefits its community. It provides shade and shelter, protects air quality, and reduces air temperatures, water runoff, and human stress. A street lined with such trees is a desirable place to live and work, and… More
I’ve discussed using trees and soils (green infrastructure) to manage stormwater in two recent webinars. This is a rich and complex topic, so to help break it down into digestible pieces I organize it in to what I call the First Principles of Urban Stormwater Systems. Those first principles are listed in the illustration above…. More
Soil. Stormwater. Sustainable Infrastructure.
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