What happens to biosolids once they are applied to soils?
In farm applications, the biosolids will normally be plowed into the top six inches of soil, leaving little visible trace on the surface. In forest applications, the biosolids are normally left on the surface to break up and blend naturally into the soils over time. In all cases, the biosolids release plant nutrients slowly, following the normal process of decay. Their exposure to air and sunlight destroys any remaining pathogens in the biosolids within a short time. As the biosolids break down they release their nutrients into the soil, where plants can absorb them through their root systems. Biosolids are applied at “agronomic” rates (carefully controlled to match plant needs) slowly providing the nutrients to the growing plants, and ensuring that surface runoff and deeper groundwater are unaffected by the application.
