Airdate: Nov 28, 2007
Scientist: Nina Bassuk
Urban Tree Planting: Soil 101
Soil quality is the greatest challenge for cityscape tree planters.
Urban Soil - It's the Pitsambience: diggingTransforming a construction area into a park means getting the ground prepped for its newest tenants: the trees. And planting trees successfully in an asphalt jungle means overcoming one big problem: the soil. I'm Jim Metzner, and this is the Pulse of the Planet. Bassuk: The soil is tremendously important for tree growth in the urban environment. It provides the nutrients, the water, and the space for the tree's roots to grow. And so, typically the biggest problem we find in urban areas is soil compaction, or just lack of soil, a lot of debris and not much real soil there.Nina Bassuk is Director of the Urban Horticulture Institute at Cornell University. She says that adjusting the soil conditions will help trees beat the stress of living in the city, even in a pit.Bassuk:: Well this is you know the worst-case scenario for trees. It's called a tree pit, where there's a hole in pavement, just a few feet square, that enables a tree to get in the ground.Bassuk says trees in that situation typically last anywhere from seven to 15 years. She and her colleagues at Cornell hope to quadruple the tree's life expectancy with specially designed soil. Bassuk: the mix is called structural soil, and it's basically a simple mix of gravel, and gel, and soil. And the reason it works well is that you can compact it yet the roots can just kind of find their way through the large pores, or the large voids caused by the gravel. So it works well from both the point of view of holding up the sidewalk and allowing tree roots to grow through it.To hear about our new Pulse of the Planet Cd, please visit our website at pulseplanet.com Pulse of the Planet is presented with support provided by the National Science Foundation. I'm Jim Metzner.