Silent Alienation of Soils through Microplastic in the Anthropocene – A Constraint for Soil Productivity?

Plastics are a characteristic signature of the Anthropocene. All types of plastics accumulate in soils where they generate a completely new and alien soil fraction, as they are robust against biological and chemical degradation. Plastic debris and microplastic unfold effects on soil physical parameters and soil fauna. Nanoplastic is taken up by plants but seems to be biochemically inert. Typically, today in average agricultural topsoils 600–700 pieces microplastic per kg soil are found. The plastic inventory of soils is at least 20 times higher than that of oceans. There are no realistic mitigation strategies to stop the accumulation of plastics in soils. This implies that the process of alienation of soils continues, may be retarded, but never halted. Henceforth, soil taxonomy needs to be extended from series level upward by the factor plastic. The process of alienation of soils through the accumulation of plastics is irreversible but will remain silent in the sense of subtle and invisible for an unforeseeable time due to analytical and statistical uncertainties. Stewardship for soil protection and welfare of next generations implies strict regulations starting with plastic product features to waste management. The final result of the presented appraisal is that the accumulation of plastic in soils is not an immediate threat to soil productivity, but nevertheless a challenge for man’s commitment to sustainable development.