The plenary sessions of the Biocycle Global 2011 conference in San Diego this week focussed on healthy soils, communities and planet. This topic has been a key objective of the Biocycle organization for 50 years. The two keynote speakers explained how soil is key to most of our ecosystem functions including water purification, food production, and the global carbon and nitrogen cycles. Without healthy soil, we don’t have life. Without addition of organic matter to our soil, we don’t have healthy soil. Composting and recycling organic matter is an important way of recycling organic matter and improving the health of our soil.
Symphony of the Soil is a fascinating web based documentary on the importance of our soil. I recommend it.
A debate unfolded during the plenary sessions – should biosolids be recycled into the soil? One viewpoint is that biosolids (solid residual from wastewater treatment) may contain unknown and untested chemicals that may negatively impact our health, and should be kept out of our soil ecosystems. The main reason for this is that we do not regulate what we through in our toilet, nor do we know the contents of some of our industrial wastewater. The other viewpoint is that biosolids compost contains carbon and plant nutrients, increases water holding capacity and productivity of soil, and has produced incredible ecosystem improvements in mine sites. The net benefit outweighs any risk.
We need to keep this dialogue going – we need to understand and be comfortable with risks, and keep them in perspective. In 2009, the Canadian Council of Ministers of the Environment published a report called “Emerging Substances of Concern in Biosolids” outlining substances that are not currently tested for, and the potential implications of some of these compounds. This report concluded that there may be substances of concern in biosolids, and that the general public needs to understand this. It also cites reports showing that a composting process reduces the concentration of some of these substances.
My own community produces a soil produced from raw biosolids. The website promoting this soil suggests that it has been tested and has been is completely safe for vegetable production. It meets the guidelines for the products that are required to be tested, but we know that there are many other compounds that we deposit into our toilets that are not tested for. I have some unease about recommending this product for vegetable production, although some communities have done this successfully for years. I do not have the same unease with using biosolids compost for landscaping, turf or other non-food growing applications. Biosolids reuse has had incredible benefits in soil and ecosystem restoration and should be promoted for that use.
We all have to be comfortable with the risks that we take with all of our activities, food we eat, and places we go. …