Recently I attended the 3rd Annual Urban Soils Symposium. Scientists are looking at urban soils as a distinct field of study that has nomenclature and characteristics different from soil science in general. I have written blog posts about soils in urban gardens outlining the awareness urban gardeners must have about the soil in their gardens. The presenters at the symposium and the questions and comments from attendees were often targeted to the urban soil issues of heavy metal contamination and what could be done. The blog post linked above gives detail about precautions to be taken. As with many issues when you get 2 or more experts discussing a topic you will have at least as many opinions as discussants. In this case the opinions ranged from - there is nothing you can do to outlining precautions that have been recommended by many scientists. The point is that there is more research to be done and that we don't have all of the answers.
Soil, water, seeds and sunlight are the essential ingredients for growing anything. Growing plants in urban areas maybe have a more difficult time with all of these factors but gardeners have always grown lush gardens in urban areas. The point for me is that we can't look at any of these factors in a vacuum. It doesn't help to look at these factors as a chicken or egg question - what comes first? It doesn't really matter what comes first if you see them all as interrelated and interdependent on each other. We can plant a seed in the soil, water the seed and let the sunshine do the job of providing the light and heat the seed requires to grow. The problems arise when one of the factors is out of balance. Too much rain, not enough rain, too much or not enough sunshine or non-viable seed are easily understandable problems usually with simple fix.
The issues with soils are much more complex and often not easily remedied. Commercial agriculture's quick fix is to just add 3 nutrients Nitrogen, Phosphorus and Potassium (NPK) to soil to grow crops. This ignores the fact that healthy soil is a living thing. Besides NPK, soils contain many micronutrients, sand, gravel, loam and living organisms both micro-organisms and larger insects. Unfortunately soils also contain poisons such as pesticides and herbicides that usually throw off the natural life in the soil. Urban soils have human made materials that make these soils unique. The important thing to remember is that we have to pay attention to our soils and be caretakers of the soil.
Community Gardeners might just consider Soil as another member of the garden community. The Soil doesn't have a voice although we tend to pay attention to the Soil only when there is a problem. A better way is to cultivate a relationship with the Soil. Give the soil compost to help it replenish its nutrients. Plant things that encourage insects, pollinators and mycelium growth to encourage the health of the soil. It is a Native American custom to give gifts back to the earth as thanks whenever something is taken from it. We should all be adopting this practice. We have to stop treating our soil like dirt.