One of the biggest complications of urban agriculture is growing food in soils that previously had types of hazardous substance or contaminants on the property. Growing just near buildings has also led to serious concerns, due to the elevated levels of lead in the soils close to buildings where lead based paint has been used. Many urban agriculture communities especially in southern California have faced growing in soils that may have contaminants and this is because of limited areas to start urban farms in dense urban areas.
It is important to understand what is in your soil and how this can lead to ongoing exposure to people who are involved with the soil. One way to better understand what contaminants you have in your soil is by doing a soil test. Soil tests may be expensive and federal funding is available to certain properties by getting involved with brownfield grants.
The greatest risk for exposure to contaminants is by breathing in the dust or getting soil in your mouth. Another exposure pathway is edible plants that can accumulate and also take up contaminants from the soil. Root vegetables have the highest potential to store and accumulate contaminants
Using recycled containers is a solution to growing food in urban areas, and this method is used to help limit the amount of leached soil contaminants into the food crop. My leading question is, does growing in recycled containers such as tin cans or recycled car tires also have the potential to leach contaminants into the soil and eventually the crop?
Growing vegetables in old tires can contribute to three environmental risks, disease, chemical and fire. Although when we first think of car tires, you think rubber but in fact these rubber tires contain a lot of petrochemical plastics.
One article by Jerry Coleby-Williams states that car tyre rubber has toxins that leach into soils over many years. Tires contain chemicals such as aluminum, cadmium, chromium,copper, iron,magnesium,sulfur and high levels of zinc. Over time these toxic substances found in tires will contaminate the soil. The leaching rate can be affected by multiple factors such as areas with higher rainfall and soils with high acidity, as this would make the leaching rate faster. Leaching is one way growing vegetables in old tires contribute to disease, especially among kids who do not have a full grown immune system.
Fire is one of the three major environmental risks tires pose in urban agriculture, and it may not seem that possible but if you do unfortunately have a fire on your farm, tires can pose serious risks. EPA does not consider tire scraps as hazardous waste but in the occurrence of a fire the tires will cause a reaction where hazardous compounds can end up in soils or waters nearby. According to the U.S Environmental Protection Agency for every million tires consumed by fire, there is about 55,000 gallons of runoff oil that pollutes our ecosystem.
Urban agriculture faces many challenges when growing in such urban dense cities, and as mentioned one of the biggest problems is soil contaminants. There are many factors that can contribute to soil contaminants in an urban farm. You can personally reduce them by thinking about what products you are bringing on to your farm. Growing containers is one major way to limit the amount of contaminants that are being added to your soil. If you did get a soil contaminants test and decided not to plant directly into the ground, it is extremely important that you do not make the mistake of plant vegetables into containers that will eventually leach contaminants.
References:
Refusing Potentially Contaminated Landscapes. (2011). Retrieved November 11, 2020, from https://www.epa.gov/sites/production/files/2014-03/documents/urban_gardening_fina_fact_sheet.pdf
Tire Fires | Scrap Tires. (n.d.). Retrieved November 10, 2020, from https://archive.epa.gov/epawaste/conserve/materials/tires/web/html/fires.html
Bradley, —, & Written ByDr. Lucy BradleyUrban Horticulture Professor and Extension SpecialistCall Dr. Lucy E-mail Dr. Lucy Horticultural Science NC State Extension. (2019, February 22). There Are Better Options Than Using Tires in the Garden. Retrieved November 10, 2020, from https://gardening.ces.ncsu.edu/2019/02/there-are-better-options-than-using-tires-in-the-garden/
Urban agriculture: The potential and challenges … – Agronomy. (n.d.). Retrieved November 13, 2020, from https://www.agronomy.org/news/science-news/urban-agriculture-potential-and-challenges-producing-food-cities
Let's Talk Urban Ag 
I like that you mentioned growing plants in containers to avoid growing on contaminated soil. Growing on contaminated soil can bring many challenges such as toxic material that can leach into the medium like car tires. A great new alternative to growing on plastic containers or toxic material, are grow bags. In plastic pots, roots tend to encircle around the pot in search of nutrients and water which can lead to root rot. However, with grow bags, when roots come in contact with the edge of the fabric they get exposed to air and drier soil, thus resulting in becoming air pruned. This prevents the circling of roots and leads to a healthier plant. They also come in a variety of colors and sizes.
Check out this link on other benefits to grow bags!
https://www.bootstrapfarmer.com/blogs/grow-bags/grow-bags-vs-pots-advantages-of-grow-bags
Here is a great video on how to start a grow bag garden!
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I found the fire risk of using tires in urban agriculture to be very interesting and something I likely would not have considered. It seems that sometimes in our efforts to reduce waste and repurpose items to keep them out of landfills we can often create new hazards. Using old railroad ties is a popular method for making raised bed planters, but depending on the age of the railroad ties they can potentially leach creosote or chromated copper arsenate. Both of theses chemicals have the potential to contaminate ground water as well as being toxic to plants, insects and wildlife.
https://www.railstotrails.org/build-trails/trail-building-toolbox/acquisition/environmental-contaminants/#:~:text=If%20the%20railroad%20ties%20are,immediately%20as%20municipal%20solid%20waste.
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After searching the web for alternative ways to grow crops not in soil, I came across this really cool company called Growtainers. Growtainers is a highly engineered modular and mobile vertical production that uses shipment containers to create a controlled environment for a wide variety of crops. These shipping containers are provide optimum controlled vertical environments that can be used for horticulture, floriculture, and agriculture purposes. In order to build the best controlled environment they can, Growtainers works with world class botanists and plant physiologists to determine the best environment for your specific product. Something really cool about these containers is that they are designed and built uniquely for your product as well as having their Growrack system be built to your specifications. Growtainers has seen significantly higher yields in shorter time than all conventional production methods and allow you to fully control the environment inside to be suit your crop needs. These containers are mobile and can be placed virtually anywhere wether it is in building, rooftop or your factory. Growtainers allow you to sustainably and economically grow almost anything you please while avoiding the need of fertile soil. As Sierra pointed out, one of the biggest complication of urban agriculture is dealing with soils that have previously been contaminated or have had hazardous substances leached in the soil. Growtainers is a perfect alternative to one of the biggest problems we face in urban ag. Overall, I think what Growtainers is doing is very innovative and a really cool way of avoiding planting into contaminated soils.
“Growtainer – The Portable Production Facility of the Future: The Production Facility of the Future.” Growtainer The Portable Production Facility of the Future, http://www.growtainers.com/.
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