Posted: 30/08/2012 at 20:18
After doing a bit of digging (no pun intended), it is probably ok to plant on the space if it is just coal/dust. But as said before, if there is any sign of coal ash, probably not a good idea. Although US environmental studies shows that small amounts of ash are beneficial to crops with little uptake of contaminants. But this depends on the crop planted, leafy plants, such as lettuce and spinach, show high concentrations of contaminants within their structure, whilst more fleshy plants like peas, beans and FRUITS tend to show small uptake but with high concentrations on the fruits surface that can be easily washed off.
Quite interesting reading about this, and may be a possible research proposal as there is not much research on the implications of small scale contamination and the uptake of contaminants by the biosphere. Most research is done on the large scale contamination caused from power plants etc.