Soil, or any other growth medium, that has grown GM plants, or plants that host GM micro-organisms, must be decontaminated ahead of any re-use. The note says this may be done by physically removing all GM plant material, GM propagative material included, as long as the soil or medium is left free of GM micro-organisms.
The graph holds this control, the 0 it maps to, and the evidence behind each claim, over MCP and REST.