When we started CRAG back in November, we invited permaculture specialists to help us address the problems of soil contamination after the fire. Emelia “Patience” Sooy is a local permaculture designer who has prepared this “Sunflower Project” as away to further repair and restore the soil around our home sites. This beautiful plan involves planting sunflowers in the burn zones, as they will take up the remaining toxins in the soil… just read all the way through to find out what to do with those flowers after they bloom!
Healing our Soils after the Fire
The Sunflower Project
After your home site has been scraped clean what next? It is likely that the soil in your yard is still contaminated with heavy metals, and hydrocarbons. These items come from burning plastic, metal, and other household items. ( lawn furniture, cars, bicycles ect.) So what do you do now? How do you repair your soils so that you can feel confidant letting your children play in the yard and grow food that is healthy to eat? I have done a fair amount of research on the topic. This is what I have found and feel will be effective in repairing our soils.
Soil Repair Tools
Bioremediation is a treatment that uses naturally occurring organisms to break down hazardous substances into less toxic or non toxic substances.
Phytoremediation is a natural sustainable way to clean contaminated soil, using plants.
Mycoremediation is a use of fungi to break down and remove toxins from the environment.
There are many plants that have been used or experimented with varying degrees of success. The plants listed below are not the only ones. There are likely many that could be useful. There are certain plants that thrive in disturbed soil. These plants play an important roll in the ecosystem. Many times they are referred to as pioneer species. Their job is to hold the soil, accumulate nutrients, fix nitrogen, and create a more moderate climate. Many of these plants are common weeds. Consider working with and within nature. Allowing these plants to do their important work along side you. Native plants are equal if not better when it comes to phytoremediation, because they have a better-developed mycrorrizal relationship. That being said this is the plan that would work just about anywhere in our area.
Select a green manure, cover crop. As a base for your other phytoremediators.
There are many seed companies that sell cover crops. It is best if they are organic or non-GMO. Here are some that I like.
Sunflower (Helianthus annuus)
Hyper accumulators that means they uptake metals and hydrocarbons in large amounts. They absorb; lead, arsenic, zinc, chromium, copper, manganese, mercury, nickel, cadmium, chromium, copper, cesium, uranium, strontium, hydrocarbons (PAHs polycyclic aromatic hydrocarbons and TPHs total petroleum hydrocarbons).
- Soraya a nice bright orange sunflower that grows to 6 feet tall with a single stem.
- Ring of Fire a multicolored starburst sunflower that’s around 3 to 4 feet tall.
- Russian Mammoth a beautiful yellow flower that can grow to be 8 feet tall!
- Velvet Queen red and orange with burgundy undertones and grows to an average of 5 feet tall.
Fava Beans (Vicia faba) Nitrogen fixing, building soil fertility also uptakes Aluminum.
Brown Mustard (Brassica nigra L.)uptakes zinc, nickel, chromium, copper, silver, and cesium.
Preparing your site for growing phytoremediators:
Once you have your plants and your seeds ready. Consider whether they can live on the site you are planting them. Is the soil compacted? If so, you may need to do some site prep to make it easier for your plants to grow. Use a digging fork to poke holes throughout the site to help break up and allow for more aerobic soil conditions. You can also drench a newly aerated site with compost tea. Spraying compost tea will inoculate your site with beneficial microorganisms. This will help your plants grow better. Then will break down and bind certain harmful chemicals including hydrocarbons in the soil.
Think about how you will irrigate your site. Will you install irrigation? Use sprinklers, hoses, or watering cans? If soil contamination is a big deal on your site, try to avoid watering methods with a lot of splash and run off. You may choose more low to the ground irrigation like, micro drip irrigation or soaker hose. If money is an issue hoses and sprinklers will work just fine.
Mulch the soil to avoid splash back with straw or wood chips to protect the seeds from birds, and direct sun. This will also help the soil hold more water for a longer time period. Greatly reducing the amount of water needed.
How to dispose of toxic material and plants.
You definitely cannot use questionable plant wastes for compost and soil creation on your site. This could spread pollution around instead of removing it,
if plants have extracted heavy metals and hydrocarbons from the soil. Once they have completed a growing cycle you could be left with plants laden with these contaminants that can technically be considered toxic waste. You need to treat these materials with caution. When you are ready to harvest your plants it is a good idea to get them tested. To see if they are too toxic too dispose of regularly.
Some people may find that their plants are within acceptable levels for municipal landfilling. You never know unless you test. If you cannot afford such testing then it would be wise to treat them as toxic and dispose of then with appropriate precautions.
What to do with plant materials?
If your plants have been tested and have acceptable levels of contamination.
If your plant waste tests toxic. Above municipal landfill guidelines. Then collect it and transport to a hazardous waste site.
- Store and concentrate waste on site
If there is an appropriate place on-site to store plant waste safely. Then consider concentrating them in part of the site. In this case, remember you are creating a sacrifice zone. This is not the worst thing considering that before your whole site may have been a sacrifice zone. If you choose to do this, choose your site carefully. You should choose the location with the appropriate characteristics.
- Dispose of plant wastes at a location that is chosen for its physical stability.
- Do not put waste near water on your site.
- Choose a place that is protected from wind and wildlife. Then clearly mark it.
- Make sure your wastes are covered. For this you should dump waste into a sturdy animal proof bin or container with lid.
- Consider purchasing a liner
When harvesting plant waste take health precautions. Especially, for the first few rounds. Wear gloves bring a change of clothes and consider using a facemask.
Test soil, grow plants, test plants, repeat.
After 14 weeks harvest the plants. Test the plants and the soil, repeat as needed. Some sources recommend 3 years for low to medium contamination. Some say up to 30 years depending on the type of contamination (nuclear fallout ect….)
You could put container beds on part of your site and grow food crops there. While phytoremediating the other portion. Once you have sufficiently remediated that portion you can move the container beds and remediate that place.
If you are hoping to rewild a site, you can plant native grasses plants and trees. Let nature take care of the rest. Native grasses have robust root systems that sequester atmospheric carbon into the soil. The root systems also bond soil contaminants. They provide habitat for beneficial microbes. Trees moderate the environment, create mulch, sequester carbon, store a lot of remaining contaminants, and provide shelter for wildlife. Work with and within nature put up birdhouses and birdbaths. This will attract native birds. The birds will bring seeds from the nearby wild-land seed bank while also delivering nutrients.
Phytoremediation to food production
After you have removed waste plants from the site. Sheet mulch the site. Sheet mulch is a form of soil building sometimes referred to as lasagna gardening.
- Slash existing vegetation.
- Laydown cardboard on top overlapping a bit. It is important that the cardboard is free of glossy paint, which can be high in lead.
- Put down several inches of the freshest manure you can get.
- Lay down several inches of straw.
- Another layer of manure.
- Than another layer of straw.
- Then a layer of finished compost.
- Then mulch with straw again.
You can plant directly into this layer. It is important to wet each layer before adding the next (as damp as a rung out sponge.) This mimics nature of a climax forest floor. Creating a sponge that will hold considerable water. The cardboard is also ideal habitat for mycelium. At this point you could roll up some oyster mushroom spawn in a piece cardboard and stick it deep in the sheet mulch. Oyster mushrooms have been shown to take up hydrocarbons and break the molecular chain, rendering them harmless. Some studies have suggested that the fruit of the mushroom is even safe to eat. Although I wouldn’t recommend it.
Working together with each other and nature, we can make our home green again. We can heal our soil and our community. We can slow, spread, sink, store, and share the water that falls on our land. We can plan for resilience, through care of the earth, care of the people, and return the surplus.
If you would like a consultation on phytoremediation, or need permaculture design, contact; Emelía Sooy at www.patient-planet.com or email me at firstname.lastname@example.org