Where I live in Denver there is a wonderful project, the GrowHaus, in the Elyria-Swansea neighborhood. Before I even took a trip out there I was told it looked like a bombed out city. There are a number of industries and train tracks that run through the area with people living wherever there is space enough for a house. In the past the area has had its share of problems with pollution. It is listed as a Superfund site because the soil is contaminated namely with arsenic and lead. There are other contaminants I am sure. What to do with such a site? How can you honestly encourage people to grow their own food when it would become contaminated?
Let me say this from the onset: I have not seen the EPA report on the levels of contamination or anything else. What follows are just my ideas in hopes to get something moving forward, maybe an idea, and begin the process of allowing people access to clean food from their own garden.
How to deal with persistent poisons like lead and arsenic? After all arsenic is a poison found in rodent kill kits. I’m not exactly sure the exact years, sometime during the Victorian era, people used arsenic in small quantities to harden nails or improve their looks and become resistant to it should anyone try to poison them which had deadly consequences in the end as arsenic accumulated in the body.
In bioremediation plants and other natural sources are used to deal with environmental pollutants. Lucky for us nature has a bacteria and an enzyme that breaks down, reduces arsenic to arsenate. I am no chemist or fully understand the process that allows this to occur. But it seems this bacteria uses arsenite as a food source. Arsenite and Arsenate are two versions with an electron shift. That’s as far as my chemistry goes. I’m sure there’s plenty of scholarly papers on the subject someone could find online.
Onward. Since we have these two toxic substances in the soil we have some ways of dealing with it: take the soil away and bury it or leave it in place. If you leave it in place there are plants along with soil organisms that can be used to help pull the toxins from the soil or deal with them in place.
In studying composting methods and soil building methods I suggest the following two things:
1) A combination of sheet mulching, worm towers and using straw bales to build up healthy soil levels to be able to grow food.
2) Create raise beds that are about four feet tall (or five) filled with clean healthy soil and worms with organic matter.
Both methods work well to get a garden started but the raised bed does little to address the toxins. People would also have to be completely committed to composting and creating new soil which is added every year. The toxins can become diluted to a point but they are not gone. People would have to go against what they know about gardening and not stir up the soil by plowing or digging. Instead, it would be a process of building up, adding to the top new soil in the form of finished compost.
That is where I would also add worm towers. A PVC pipe with holes drilled in the bottom part of it which is buried in the ground. Compost materials would be added through the top closing it off with a cloth stretched over the opening. This encourages the materials to break down which encourages worms to come into the area to eat and deposit their poop. They will also go in and out of the pipe depositing their poop outside the pipe. Worm poop is a rich fertilizer which can help build up soil nutrients. This will encourage a host of other organisms to move in that can work with the contaminants to help make them not as harmful. Mushrooms have also been used to help clean up sites because they release various enzymes which break things down and recombine substances to make them bio-available for new plants.
Again, this is where I am a little lost in the chemistry. Arsenic is technically something that can’t be broken down. It is a metalloid, being the same family of metal like substances.
By combining methods of bioremediation, sheet mulching, adding new organic matter like compost, clean leaves or straw will help dilute the lead and arsenic in the soil. It is by dilution and as the soil becomes more active with organisms of all kinds that the toxins can become less of a problem. It would take quite a bit of work and time to accomplish this, but it is possible. Bioremediation makes use of microorganisms which can reduce, eliminate, contain, or transform to a more benign state contaminants present in the soil.
By applying the methods of sheet mulching, composting, worm towers, and adding a good layer of organic material of leaves or straw can help those microorganisms to do their job much better. Feeding them will build a healthier soil and every year the process continues and the better the harvest becomes.
Just so people are clear, I am not claiming that all the poisons will just disappear or be gone in a year and everything comes up roses. This is a process which takes time and it may be that the first year will be a year of planting and discarding plants while adding more compost and organic materials the whole time. This process has been used and can certainly work for the Elyria-Swansea area too. I would love to be there to help this process of bioremediation along, and then maybe someone can teach me the chemistry behind this process.
Build some soil. Grow some food.