Question: What makes that “fresh earth” smell in spring? What is that? Answer: In a word, geosmin. Geosmin is an organic compound released by a group of soil microorganisms called actinomycetes. Actinomycetes are filamentous “prokaryotes.” In other words, they are microscopic organisms whose cells have no “nucleus” enclosing their DNA. Organisms that do have cell nuclei—like plants,… More
“The soil here is terrible.” This is something we hear a lot during design discussions. People often assume that soils in heavily developed environments can’t possibly be biologically sound for plant life. In some cases, this is true. But in others it isn’t, and the only way to know for sure is to do a… More
One of our specialties at The Kestrel Design Group is designing urban tree systems (especially designing urban tree systems to maximize stormwater benefits). One question we are regularly asked on urban tree projects is whether or not soil organic matter will become too low or depleted when trees are surrounded by pavement and leaves are no… More
In October, I wrote about some of our concerns with Philadelphia’s highly-lauded green infrastructure plan, now codified in their Green Streets Design Manual. This plan has received more praise and recognition than any other citywide green infrastructure policy that I’m aware of (here are a few examples). I’m thrilled to see a major green infrastructure… More
Last month we hosted our first webinar of 2014, a conversation between James Urban, FASLA, and Doug Merkler, Resource Soil Scientist for Southern Nevada with the USDA, on the basics of designing for desert and arid soils. If you missed the live event, a recording is now available on our YouTube channel. I have to personally share how… 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
Soil. Stormwater. Sustainable Infrastructure.
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