Natural microorganisms can extract chemical energy for use in their life processes from utilizable carbon sources in organic matter or biodegradable plastic materials in the presence of oxygen in compost (aerobic) or in the absence of oxygen in soil (anaerobic) by turning them into biomass, water and carbon dioxide (CO2).
CO2 is used as the quantitative measure for biodegradation standards to determine the ability of natural microorganisms to assimilate carbon in biodegradable plastics in a short time period
- Composting Standards: ASTM D6400 (USA), EN 13432 (EU), ISO 17088 (International)
- Anaerobically Standards: Biodegradable Plastics Mulches in Soil Environment ASTM work item 29802
Currently plastic mulches are all made from Polyethylene (PE) plastics like LDPE, LLDPE or HDPE, which are scientifically proven not to be biodegradable, hence do not pass those biodegradation standards!
However some PE mulches supplemented with specific oxidation additives claim to be “photo- or oxo-biodegradable". These terms suggests that those PE mulches can undergo biodegradation in compost or soil, but in essence it is a “vanishing trick” converting visible to the human eye PE bulk mulch by a chemical reaction into invisible PE particle waste, which remain and accumulate in soil posing the risk to contaminate produce over time.
