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Monday, March 28, 2011

More on Soil


An Associated Press article about urban soils ran in over 100 news outlets a couple of days ago with many headlines using the word "tainted".  Most of the articles made the case that the benefits of community gardening and urban agriculture outweighed the risks associated with "tainted" soils. Gardeners were encouraged to have their soil tested.
The articles can be found in:
NPR
Huffington Post
Battle Creek Enquirer

The director of the Cornell Waste Management Institute was quoted saying that a pilot study of 44 gardens found less than 10% of the gardens had high levels of Lead. This seems to contradict the finding of the Brooklyn College Environmental Science Analytical Center that 51% of the urban soil samples tested at the lab exceeded  the New York State Dept. of Environmental Conservation's Soil Cleanup Objectives  restricted use levels. But what this does is point out the lack of consistent standards for what are acceptable levels of heavy metals. 


Sunday, March 27, 2011

It's the Soil...

Usually in these pages I write about water - rainwater harvesting - because access to water is so important to sustainable community gardens. The tsunami in Japan showed the sheer power of water to destroy, the need for water to avoid a nuclear disaster and how this resource can be made unusable by radiation.
                                Rainwater Harvesting System at the River Garden in the Bronx

Soil is equally important in a community garden. A fragile resource that can be lost through erosion, contaminated by heavy metals and chemicals and depleted of nutrients, oxygen and beneficial soil organisms if the soil is not cared for properly.

Most community gardens are in urban areas and on land that may have been contaminated by a prior use. There has always been a concern about potentially toxic chemicals or heavy metals that might still be present in the soil and end up being absorbed by community gardeners through the skin, by inhalation or through eating the vegetables grown in this soil. I am not aware of any poisonings or sicknesses caused this way. Community gardeners have always been advised to have their soil tested to know if special precautions need to be taken.

            Witch Hazel flowering in early March at the Jacquline Denise Davis Garden in the Bronx

The heavy metals of concern are Arsenic, Cadmium, Chromium,Nickel and Lead. An excellent heavy metals fact sheet published by the Environmental Sciences Analytical Center @Brooklyn College gives some interesting facts about the soils they have tested. The median levels of the five heavy metals results found in urban soils primarily taken from NYC gardens are anywhere from 2X the levels of Nickel to 20X the levels of Lead as found in rural soils in NY State. That sounds bad but even with these numbers there are best management practices for gardeners to follow to avoid any problems. Also, soil tests are based on mixed samples taken at different depths and from random spots in the garden. A soil test that shows high levels of Lead for example could have been taken from a spot that is contaminated by lead based paint chips from an adjacent building or from remnants of the building formerly occupying the site of the garden.

"Native" soil in a Bronx community garden

In my experience, most community gardeners grow in soil that has been brought in by a truckload and confined in a raised bed and are not planting edible plants in the existing soil. In addition, plants will be less likely to uptake lead in soils that includes 5 to 10% organic matter (compost). Slightly acidic soils with a pH of 6.5 to 7  and soils with the proper amount of phosphorus will bind the lead particles in the soil and make it  less available to plants. Gardeners who realize the importance of healthy soil spend time building up the nutrients and soil organisms. This is another example of sustainable gardening and yet another reason to preserve gardens. 

Soils that have been improved over years of stewardship are not easily replaced. A community garden destroyed or moved to a different location is not the same community garden. The centuries old villages destroyed by the tsunami will be difficult to rebuild in a short time and land contaminated by radiation from the still unfolding and worsening crisis at the nuclear power plants in Fukushima, Japan may not be usable for years, even decades. Soil, water  and community gardens are resources to be preserved and protected and not abused because of carelessness or for profit.

      A recently completed RWH system at the Belmont Little Farmers community garden in the Bronx 

Tuesday, March 15, 2011

Spring Energizing Events

This is the season for preseason community gardening conferences. A time for those new to community gardening to learn the skills they need to garden, organize, compost or distinguish between a pest and a beneficial insect. A time for experienced folks to share their knowledge, learn something new and be energized for the gardening season ahead. I think I've experienced all of these things.

I've had the pleasure of making rainwater harvesting presentations at a community gardening symposium on March 3rd with over 100 in attendance at the Frelinghuysen Arboretum in Morris County, New Jersey. The county and other counties and small towns have community gardens in areas that I would call suburban.  Community gardening is happening in these areas as much as in the urban centers of New Jersey like Newark, Trenton and Camden. The attendees were very interested in rainwater harvesting and many were making plans to capture rainwater in their gardens.

On Saturday, March 12th, we set up the GrowNYC rainwater harvesting display at Making Brooklyn Bloom, the annual gardening festival sponsored by Brooklyn GreenBridge, the outreach program of the Brooklyn Botanic Garden. I was almost hoarse after speaking practically non-stop for about 5 hours to folks who had rainwater harvesting systems in their backyards, front yards and community gardens. Others came by for advice on how to build new systems in their own yards or for others as a business. All kinds of people were talking sustainability, storm water management and green technologies. It made this early season event quite energizing.

Still to come is the GreenThumb GrowTogether an day long event attended by over 1000 community gardeners who attend workshops and gather information during the networking session. I will be leading 2 workshops, one on rainwater harvesting and one a hands on workshop where we will be making the recycled plastic planter bags that I have been using for vertical gardening.

I hope to have photos and video of the vertical gardening workshop. The rainwater harvesting workshop at the Frelinghuysen Arboretum was videotaped and will be available in some form soon which I will pass along when it is available. Happy Spring events!